VTNE: Basics of Surgical Preparation And Assisting

The ability to properly prepare the animal, surgical suite, and surgical personnel for a procedure is very important in veterinary medicine. Proper surgical preparation increases surgical survival rates and decreases complications by decreasing the number of pathogenic organisms that may contaminate the surgical field, providing a routine that minimizes possible errors before, during, and after the procedure and providing adequate record keeping for following potentially harmful trends in the animal's vital signs during the anesthetic period.

Knowledge of appropriate instrumentation and procedures for common veterinary surgeries allows the technician to be better prepared for surgery. Proper patient and pack preparation save anesthetic time and also increase survival rates for the animal. The watchword for veterinary surgery is preparedness. The better prepared the technician is prior to beginning the surgical procedure, the lower the likelihood of complications for the patient.

Key surgical terms to know:
absorbable
antisepsis
aponeurosis
asepsis
Caslick's procedure
caudectomy
chlorhexidine
cleanliness
closed gloving
cryptorchidectomy
dehiscence
disinfection
elective surgery
ethylene oxide
extubation
fenestrated
indicator strips
intraoperative
intubation
iodorphors
laparotomy
nonabsorbable
nonelective surgery
onychectomy
open gloving
orchidectomy
ovariohysterectomy
pack
postoperative
preoperative
sterility
surgeon
zoonotic

Surgical preparation and assisting can be broken down into four main topics:
- preoperative preparation
- intraoperative procedures
- postoperative procedures
- common surgical procedures

Preoperative Preparation
Proper preoperative preparation of the patient, instruments, and surgical suite will reduce the infection rate (morbidity) and increase the success of any surgical procedure. Before the 1900s, disinfection, sterile instruments, and hand washing prior to surgery (whether of animals or people) were not commonly used. Even anesthesia was a rarity. The anesthetic usually used was either ether, liquor, or chloroform, all of which caused liver problems. As a result, many patients died from infection and/or shock. Since the institution of good nursing protocols including asepsis (without germs), patient survival rate has increased in both humans and animals and there have been fewer postoperative complications.

Cleanliness, Disinfection, Antisepsis, Asepsis, Sterility
These five words are very important for everyone in the veterinary clinic. Not only do animals need to be protected from nosocomial infections (infections coming from the hospital) when they come in for surgery, but equally important, the human population must be protected from zoonotic diseases (animal diseases that may be infectious to humans). In order to achieve these goals, maintaining a clean, clutter-free facility with a minimum of dust-collecting surfaces is necessary. All surfaces should be able to be wiped down or laundered. Veterinary technicians are often in charge of clinic maintenance, which includes providing a clean and polished facility. Not only does a clean, clutter-free facility help to reduce infection rate and minimize odors, it also demonstrates that the clinic is professional. Clients notice stains, dust, feces in the driveway, urine puddles, and odors. Impressions are important, and the clinic should strive to make good ones every day.
Cleanliness is the removal of dirt and debris from a surface. This may be performed with soap and water and does not require disinfection.
Disinfection is the removal of living organisms from a surface to an acceptable level that will not cause/transmit infection. This is performed with a disinfectant. Disinfection can only be performed on nonliving objects because the process kills living organisms (including the patient's cells). Contact time, or the amount of time the product is in contact with the surface, is important. Follow label directions for the product. Disinfectants do not necessarily clean, so cleaning should be performed prior to disinfection. Higher concentrations of disinfectants do not mean that the mixture will be stronger. In many cases, in fact, a concentration that is too high will make a product less effective.
Antisepsis is the removal of infectious organisms from a living surface to an acceptable level. This is performed with an antiseptic. Antiseptics work best at the correct dilution, and contact time is important. Be sure to follow label directions. Remember that it is only possible to disinfect nonliving surfaces.
Asepsis is the condition of lacking infectious organisms. This is what preoperative preparation hopes to achieve. By proper antisepsis and disinfection and the use of sterile instruments, drapes, and technique, the surgical field can be kept free of infectious organisms that could cause problems with healing.

Products
Various products can be used as disinfectants, antiseptics, or both. The category depends on the amount of tissue damage or toxicity that the product causes. Clean surfaces without visible soil, oils, or dirt are easier to disinfect than dirty surfaces and will require shorter contact times. It is important to mix disinfectants and antiseptics according to label directions.

Antiseptics
The two most commonly used antiseptics are povidone-iodine (an antimicrobial) and chlorhexidine (an antibacterial). They are commonly used as surgical scrubs, superficial disinfectants, and wound flushes. Iodine will kill tissues in high concentrations, but is a very effective bactericide. Most of the iodines used in clinical practice are iodophors. Iodophors are iodine molecules complexed with a surfactant (soap) that allows the iodine to be released slowly. Iodophors such as povidone-iodine tend to stain less and are less toxic to cells and tissues. Iodine will provide residual antiseptic activity for several hours after scrubbing. Alcohol will destroy the residual benefits of iodine and should not be used as the alternating scrub. Saline or water should be used instead. Some animals (and people) are sensitive to iodine compounds and will develop rashes. Long-term use can lead to absorption of the iodine through the skin, which can cause thyroid problems.
Chlorhexidine is effective against bacteria, viruses, and fungi. The residual antisepsis is not affected by alcohol and it may be used on relatively dirty areas (iodine should only be used on precleaned tissue). It is superior to iodine as a surgical scrub and a hand scrub because of the spectrum of organisms that it is effective against and its quick onset of action. Chlorhexidine is a rapid antiseptic that requires a short contact time. Very dilute chlorhexidine (1:40 dilution with water or saline) may be used as a flush. Higher concentrations will destroy cells and tissues.

Alcohols and phenols have both been used as antiseptics and disinfectants. The phenols have been phased out because of the high potential for toxicity (especially in cats). Alcohols (ethyl and isopropyl) should only be used on intact skin because they will cause pain and cell death in subcutaneous tissues. Alcohols have no residual effect and are not effective against fungus and bacterial spores. Most of the time, alcohol scrubs are alternated with chlorhexidine scrubs to help cleanse, degrease, and scrub an area for surgery.

Disinfectants
Disinfectants are generally not used on living tissue because they cause cell death at effective concentrations. They are usually excellent bactericides, but the virucidal and fungicidal properties vary depending on the product.
Quaternary ammonium compounds are actually soaps or detergents. They have very little effect on naked viruses or spores (which do not have a fat coating), but have some cleaning activity along with disinfection. Viruses with a lipid coating and gram-negative bacteria are particularly susceptible to quaternary ammonium compounds because these compounds destroy the lipids in the cell walls. Benzalkonium chloride is the most common. If hard water (water that contains a high level of calcium salts) is used, the solution may be inactivated by the chemical reaction with the salts. Quaternary ammonium compounds should not be used to clean items containing cotton (surgical drapes or gowns) because cotton, a natural fiber, also inactivates the compound.
Sodium hypochlorite, or bleach, is an excellent disinfectant. It is particularly good for the elimination of bacteria and viruses and some fungi (dermatophytes). It will kill any living tissue and should not be used on skin or in open wounds.
Formaldehyde and glutaraldehyde are toxic and irritating to tissues. They should never be used for antisepsis, but are effective disinfectants if given enough contact time as stated on the labels.

Instrumentation
The instrumentation for sterilization varies with the type of hospital, the type of equipment, and the surgeon's preference. Some sterilization procedures are dangerous for the operator. Prior to a surgical procedure, technicians should always familiarize themselves with the operation of equipment as well as the safety protocols. Untrained personnel should not operate sterilization equipment.
Most prepackaged items, such as suture material, injectable medications and vaccines, gloves, and single-use drapes and gowns, come in presterilized packaging. Sterilization occurs in the factory and may be either by irradiation (used for heat-sensitive items such as latex gloves and paper) or filtration (used for liquids such as injectables).

Steam Autoclave
Steam is the most commonly used method of sterilization. In general, heat will destroy bacteria by destroying protein. Boiling water by itself is not a good sterilant. Steam that is generated by boiling water at increased pressures has better penetration and will destroy all organisms including spore-forming bacteria. Steam should be at 121° Celsius (250° Fahrenheit) for a minimum of 15 minutes in order to sterilize an item completely. In other words, the 15 minutes of contact time is counted not from the time the autoclave is turned on but from the time the pressure and temperature reach the proper level. Instruments may become dulled with steam, so delicate instruments should be processed with gas or plasma sterilization. Steam should not be used on rubber or plastic. Burns and explosions can occur if the autoclave is not properly maintained and operated. Untrained personnel should not operate autoclaves.
Autoclaves range from kitchen pressure cookers to large, walk-in autoclaves at research facilities. Pressure cookers are not good autoclaves because it is impossible to measure the temperature and pressure in the interior. True autoclaves have pressure and temperature gauges that allow better quality control. Most autoclaves in practice are small, countertop, gravity-displacement autoclaves that allow the air to escape from the bottom of the autoclave as the steam rises to the correct pressure in the interior.
After the cycle is completed, the autoclave door should be cracked open slightly to allow the escape of residual steam. Opening the door completely will actually cause condensation to form on the pack. If the pack becomes wet, it is no longer considered sterile and the process must be repeated. The packs should be removed from the autoclave after 20 minutes.

Plasma
Plasma uses hydrogen peroxide gas to sterilize instruments. It may be used for most of the same materials as steam. Wood, paper, plastics, and liquids cannot be sterilized with plasma.
Plasma sterilizers are really vacuum chambers. The chamber is evacuated (placed in a vacuum) and hydrogen peroxide is injected and vaporized. The vapor is bombarded with radio waves, which makes plasma. The peroxide molecules in the plasma are actually free radicals, which means that they have unpaired electrons in their outer shell and are highly reactive. These electrons attack bacteria and viruses and change the protein and nucleic acid structures, destroying them.
Indicator strips are available to indicate the presence of hydrogen gas but they do not indicate the presence of free radicals. Biological indicators, available from distribution companies, must be used. Biological indicators contain resistant bacteria that will be killed by the sterilization process. Failure of the bacteria to grow indicates adequate sterilization.

Gas Sterilization
Gas sterilization uses ethylene oxide gas to sterilize materials. The benefit of ethylene oxide sterilization is that it can be used to sterilize materials that will melt or be damaged by steam or plasma, such as drills, cords, tubing, rubber, and fine-tipped ophthalmic instruments. Ethylene oxide will destroy bacteria, fungi, and viruses by causing alkylation of the DNA.
Ethylene oxide is very dangerous and should never be used by untrained personnel. It is flammable, explosive, and highly toxic. Gas sterilizers should be vented to the outside to prevent intoxication of personnel. Packs sterilized with ethylene oxide should be aerated for a minimum of seven days prior to use to prevent intoxication of surgical personnel on opening the pack. Toxicity reactions include fetal mutations, miscarriage, cancer, convulsions, respiratory edema, and death.
Packs for ethylene oxide sterilization should be packaged in plastic and paper packs (steripouches) and sealed before being placed in the chamber. The gas penetrates plastic and paper. Chemical indicators are available, but, as with other methods, biological indicators are the best for evaluation of sterility.
Ethylene oxide chambers are operated by breaking the vial of chemical in a pouch and closing the door of the chamber. Humidity must also be present to enhance killing, but it does not need to be steam under pressure. The higher the temperature, the faster the ethylene oxide will sterilize, but 12 hours at room temperature will be adequate, so heating is not necessary.

Dry Heat
Dry heat is used to sterilize items that cannot tolerate moisture, including powder, dirt, bedding, and so on. An advantage of dry heat is that it will not cause corrosion and dulling of blade edges as steam does. The disadvantage is that it takes more time and higher temperatures than steam. Dry heat must be applied at either 320° Fahrenheit for 2 hours or 340° Fahrenheit for 1 hour. Dry heat should be in a convection oven that moves the heated air over the instruments. Regular ovens should not be used because they heat unevenly.

Cold Sterilization
Cold sterilization typically uses glutaraldehyde. Contact time for cold sterile is a minimum of 3 hours in solution. This process should only be used for nonsterile procedures because of the possibility of contamination when instruments are removed with a contaminated tool. The instruments must be cleaned thoroughly and dried prior to being placed in the bath to ensure the proper concentration of glutaraldehyde and the proper penetration of the solution. Instruments must be rinsed prior to use because glutaraldehyde is toxic to tissues.
Chlorhexidine may also be used, but it tends to crystallize and may cause corrosion of instruments over time. With any cold sterilization, cleaning an instrument that has fallen on the floor and putting it into the cold sterile bath for 5 minutes (which is common in many veterinary practices), is not sufficient. A minimum of 3 hours contact time is essential.

Preoperative Preparation of the Surgical Suite
The cleanliness and level of disinfection should be highest in the surgical suite. The surgical suite should be swept, dusted, and mopped prior to the rest of the clinic in order to keep it as clean as possible. All cleaning equipment should be specific for the surgical suite and not used for the rest of the hospital. Dirty mops and mop buckets may have contaminants that can reduce the asepsis of the surgical suite. Mop heads should be laundered regularly. All surfaces in the surgical suite should be nonporous, and there should be nothing in the surgical suite that cannot undergo disinfection. If delicate instruments that cannot be disinfected or cleaned easily must be in the surgical suite, they should be covered with a drape between procedures to decrease dust collection. Even if the surgical suite is not used on a particular day, it should still be on the cleaning rotation to maintain disinfection.
All surfaces, whether they are visible or not, should be cleaned. Surgical tables (including the sides and undersides) and lights should be cleaned after each procedure because they are closest to the surgical site. Anesthesia machine hoses and surfaces should be cleaned frequently for the same reason.
Surgical packs should not be stored in the surgery room itself, because of the possibility of dust collection and contamination. A pass-through door or window should be available to pass the instruments into the surgery from the prep room to minimize contamination and reduce clutter.
If possible, the airflow should be higher in the surgical suite than in the rest of the hospital to reduce the possibility of contaminated air from the rest of the hospital getting into the aseptic atmosphere of the surgery. The doors should be able to be pushed open and swing closed. This will decrease the necessity of opening and closing doors with the hands and enable asepsis to be maintained.

Preoperative Preparation of the Surgical Pack
Surgical packs consist of instruments and other items necessary for a particular surgical procedure. Every veterinarian and every hospital is different with respect to the items that are chosen for the pack. Choices of instruments, numbers of gauze sponges, and other items are all variable.

The important things to remember are:
- the packs must remain sterile until opened, - the packs should be able to be opened easily, and - the packs should be consistent in numbers of items within a given clinic.
If the pack cannot be opened easily, accidents may occur that can affect sterility of the instruments, rendering the pack useless. If the technician makes five different spay packs with varying numbers of hemostats and gauze sponges, it will be impossible to tell whether or not an item was left inside the animal. Instruments and gauze sponges should be counted before and after every procedure.
Proper pack preparation means that the pack should be made the same way every time. Generally, packs are double-wrapped in paper or cloth or in plastic envelopes. Indicator strips sensitive to the type of sterilization used (steam or gas) should be placed inside the pack along with the instruments to ensure that proper sterilization has occurred. Steam sterilization tape is not adequate for assessing proper penetration of the pack with steam if used alone.
Instruments should also be placed in the pack or on the tray in a specific order to make instrument selection easier for the veterinarian or veterinary assistant during surgery. This will save the surgeon time and will increase the surgeon's ability to focus on the task at hand.

Cleaning Instruments
Prior to inclusion in a pack, instruments should be clean, lubricated, and dry and must be checked for functionality. They should open and close properly, the box locks should lock the instrument, the tines should not be bent, and the tips should meet properly. Improperly operating instruments should either be discarded or sent back to the factory for repair or replacement. Scissors, osteotomes, and elevators should be sharpened and assessed for chips and bent shafts prior to inclusion in a pack. See Postoperative Instrument and Equipment Care on page 100 for a more complete discussion of instrument care.

Packing the Pack
There should be a basic pack inventory for every type of pack in the hospital. This inventory should include:
- the number and type of each instrument, - the number of gauze sponges, towels, and drapes included in the pack, and - any additional instruments that may need to be added per procedure; these should be made available in separate packs.

Use of an instrument tray will keep the items organized and easily accessible by the surgeon. Pack wraps (whether cloth or paper) should be inspected for holes or wear and discarded when appropriate. Any holes or thin spots are opportunities for contamination of the pack and prevent asepsis from being achieved.

Air circulation within the pack is necessary for adequate steam and gas penetration. Wrapping a pack too tightly (overstuffing) can decrease the ability to sterilize instruments. For the same reason, putting too many packs in the autoclave can also decrease the ability to achieve sterilization. Instruments within the pack should be in the open position (lock boxes should be open, not closed) to enable even heating.
Packs should be wrapped tightly enough and sturdily enough to prevent accidental opening. Wrapping with an envelope closure is the best method. Tabs enable the technician to open the packs without contaminating the interior.
Packs should be labeled with the pack type, the date of sterilization, and the technician's name or initials. They should then be sealed with tape.

Storage of Packs and Longevity
Packs should be stored in a closed cabinet to prevent dust formation. Packs should be inspected frequently. If a pack gets wet, is dropped, or the tape seal is broken, it is no longer considered sterile and must be recleaned and resterilized prior to use. Water will wick contaminants and bacteria into the sterile environment, so packs that become wet or are not completely dried after removal from the autoclave must be resterilized. Double-wrapped muslin or paper packs will remain sterile for 7 to 8 weeks if stored in a clean, closed cabinet. Storage in an open cabinet or on a shelf will decrease the effectiveness of sterilization by about half.

Preoperative Preparation of the Patient
The patient is the most important consideration for the technician. Proper preparation of the patient, the operating room, and the surgeon will reduce the risk of intra- and postoperative complications, including infection. All equipment (packs, gowns, gloves, possible suture material, and monitoring equipment) should be gathered and available prior to the surgery to minimize setup time and enable continuous patient monitoring. Anesthesia machines, monitoring equipment, and heat sources should be checked for proper function prior to beginning a procedure. A checklist will ensure consistency. Anesthetics should be prepared in labeled syringes (patient's name, drug, concentration, and dose). A crash cart containing emergency drugs and equipment should be available. Endotracheal tubes should be selected and a laryngoscope with a working light should be available.

Preoperative Laboratory Work
A minimum database is recommended prior to any surgical procedure. The definition of minimum database will vary with the veterinarian and the practice, but generally includes at least a physical examination, PCV (packed cell volume), and TP (total protein). Many practices may recommend a CBC (complete blood count) and chemistry panel as well. In susceptible breeds, or prior to surgeries with potential for excessive hemorrhage, such as ear crops, a von Willebrand test or BMBT (buccal mucosal bleeding time) may be recommended to rule out bleeding tendencies.

The physical examination is especially important to ensure the right animal, right sex, right body part, and right procedure. Never rely on the receptionist or the owner for all the information on a particular animal. It is not uncommon for owners to misidentify the sex of a cat or a rabbit coming in for a neutering procedure, for example. Animals should be identified with their full name and surgical procedure on a cage card and an identification collar to prevent mistakes. Special instructions such as NPO (nil per os, or nothing by mouth) should also be on the cage card as well. Physical exam findings should be in the record in SOAP (subjective, objective, assessment, and plan) format for the veterinarian to review prior to the procedure. All blood should be drawn and the results ready prior to induction (placing the animal under anesthesia).

Owners should be informed by phone of any deviation from the plan. For this reason, it is important to go over an estimate of potential costs and get the owner's contact information (including cell phone and e-mail) prior to admission. Owners should also sign a consent form and possibly a resuscitation consent form in case of anesthetic complications. The technician should discuss the risks of anesthesia with the owner prior to surgery. This will not only inform the owner, but may protect the hospital from potential legal action in case of a surgical or anesthetic complication.

Induction
Modern anesthetic techniques usually involve multiple drugs giving a smoother anesthetic experience. It is important for the technician to be familiar with the specific combination of drugs used by each veterinarian in the practice, including dosages, routes of administration, and order of administration. Anesthetic protocols usually include preanesthetic, anesthesia induction, maintenance, and pain control agents. All medications and induction equipment should be prepared prior to induction and labeled as stated in the section on Preoperative Preparation of the Patient. This will save time, smooth the induction process, and reduce distraction of the technician from patient monitoring.

Surgical patients should have an indwelling catheter placed prior to surgery to enable anesthetic, fluid, and emergency drug administration. Fluid administration is important during surgery because anesthesia reduces blood pressure and renal blood flow and can lead to shock syndromes. Shock is an emergency condition characterized by a decrease in systemic blood pressure or cardiac output. Warm fluid therapy is a means of increasing body temperature, which also tends to drop several degrees during surgery. Maintaining blood pressure and body temperature will decrease recovery times and intra- and postoperative complications.

Given a few minutes prior to induction, the preanesthetic agent is generally a sedative that reduces the anxiety of the animal during induction and can reduce the amount of induction/maintenance anesthesia needed, thereby increasing the safety of the anesthesia. It may also smooth the recovery process by slowing this process, allowing the animal to adjust to the altered state of consciousness. This step may be omitted with certain anesthetic induction agents. Time of preanesthetic administration should be recorded on the anesthesia record along with the dose and concentration. Some pain control agents (NSAIDs) are given prior to surgery, while some are used as preanesthetics or intraoperatively. Check with the veterinarian for administration times.

Anesthetic induction is the administration of the induction agent. This is usually an injectable anesthetic agent followed by gas anesthesia. All equipment that may be needed during induction should be available. This may include anesthetic masks, induction chambers for cats and some exotic animals (but never for dogs), endotracheal tubes, ties (used to anchor the endotracheal tube to the animal), an empty syringe to inflate the endotracheal tube cuff, a working laryngoscope (with a light), and sterile lube (lubricant). The induction agent is administered and the animal is watched for relaxation and decreased jaw tone. Once this occurs, the animal is intubated.

Intubation is the process of placing the endotracheal tube into the trachea. The tube should be premeasured both for diameter and length. The diameter of the tube should be large enough to have the maximum gas flow, but narrow enough to fit into the trachea comfortably. Too large a diameter may cause necrosis (tissue death) of the trachea. Too small a tube will have increased resistance of flow and may interfere with gas exchange at the alveolus. The length of the tube should be measured by placing the tube externally on the animal from the tip of the nose to the thoracic inlet (beginning of the shoulder blade). If a tube is too long, it may enter a single bronchus and only ventilate one lung. If it is too short, it may not stay in the trachea.

Once jaw tone is decreased, an assistant should hold the maxilla behind the upper canines and extend the neck to straighten out the larynx and trachea. The technician performing the intubation will open the mouth by inserting the finger between the incisors and grabbing the tongue. The tongue is extended to bring the larynx further forward, because the hyoid apparatus that holds the larynx is connected to the base of the tongue. The epiglottis is identified. If it is in normal placement, the tip will be hooked over the soft palate and make visualization of the glottis (the opening in the larynx leading to the trachea defined by the vocal cords and arytenoid cartilage) impossible. If it is in this location, it may be dislodged with the tip of the endotracheal tube and the glottis will be visualized over the leaf-shaped epiglottis. The tube is advanced between the vocal cords and tied in place. The animal is connected to the anesthesia machine (with oxygen and gas anesthetic turned on) and the cuff is inflated. The inflated cuff should prevent gas leakage around the tube and help to prevent aspiration of oral and pharyngeal contents. Overinflation of the cuff may cause pressure necrosis and should be avoided. Cuffs should be avoided completely in animals with complete tracheal rings, such as birds and reptiles. Mammals have a trachealis dorsalis muscle connecting the c-shaped rings of the trachea, and this provides the ability to stretch when the cuff is inflated. Care must be taken inflating cuffs when dealing with cats, as overinflation can lead to tracheal rupture.

The technician should then check whether the endotracheal tube is lodged in the esophagus or the trachea by checking for breathing through the tube. Another method is to palpate the throat area. The trachea should be palpable in nonintubated animals because of the cartilage rings. In intubated animals, if only one cylindrical tube is palpable, the endotracheal tube is correctly placed in the trachea. If two tubes are palpable, the endotracheal tube is in the esophagus and should be removed prior to attempting intubation again.

The gas anesthesia and oxygen flow are then turned on and the machine is connected to the tube. A surgical plane of anesthesia is attained when the animal's eye has rolled to the ventromedial position and there is a loss of the palpebral reflex and jaw tone.
Once a surgical plane of anesthesia is reached, the animal may be prepped for surgery. The anesthetist should note the induction time on the anesthetic record and begin monitoring.

Preoperative Shaving and Scrubbing
Proper preoperative preparation decreases the chances of postoperative infection and breaks in intraoperative asepsis. A routine for this preparation is important. If the same steps are followed prior to each surgery, there are fewer opportunities for costly mistakes. Knowing the theory behind the procedures will help you understand their importance.

Shaving
Hair acts as a wick, drawing moisture, bacteria, and dirt into a sterile field. Asepsis cannot be achieved on a hairy animal so the patient must be shaved prior to the procedure. Typically, the boundary of the shaved area should be a minimum of 2 to 4 cm from the edge of the incision, depending on the veterinarian's preference. Some veterinarians like a very broad surgical field, others prefer a small field. Some veterinarians also prefer a smaller incision. In general, if the hair on the animal's sides is long enough to get into the sterile field, it should be clipped. If an orthopedic procedure is being performed, the entire circumference of the limb should be shaved and prepped.
The shaving should be done with a #40 clipper blade, initially in the direction of the hair growth then against the hair growth. The removed hair should be vacuumed from the animal. A lint roller may be used to remove smaller hair fragments from the animal. Some veterinarians prefer a close shave with a double-edged razor after the clip. The area should be scrubbed with surgical scrub to make a lather, then shaved in the direction of hair growth. Hair and dead skin cells may then be removed with a wet sponge.
It is important to prevent irritation of the skin (clipper burn) during the surgical prep. Clipper burn causes irritation similar to small cuts (like paper cuts) that can increase postoperative self-mutilation by the animal. It will also increase the tendency for postoperative infection and possible dehiscence of the wound (opening of the wound prior to healing). Excessive pressure during clipping should be avoided and the blade should be held so that the face is as close to parallel to the skin as possible. The skin should be pulled taut to prevent catching the skin in the tines of the blade. Failure to tighten the skin causes chatter marks, which look like railroad tracks. These recommendations are even more important in thin-skinned animals such as cats and rabbits because of the danger of skin tears.
Dull clippers increase the chances of clipper burn, so proper maintenance is important. Clipper blades should be cleaned thoroughly after every use to decrease the potential for disease and parasite transmission. Clippers should be stored in a disinfectant/lubrication bath between uses.

Scrubbing
To scrub means to remove contaminants such as bacteria from the animal's body prior to surgery. It consists of two steps. The first, or preliminary, scrub occurs in the induction area. Alternating scrubs are performed with an antiseptic surgical scrub such as povidone-iodine or chlorhexidine on gauze sponges. If chlorhexidine is used, the second scrub should be alcohol. If povidone-iodine is used, the second scrub should be saline because alcohol removes the long-acting antiseptic properties of iodine. Exam gloves should be worn when performing a preliminary scrub to minimize contamination of the field with bacteria and fungi that may be on the hands.
The technique for the preliminary scrub should be to start with the surgical scrub over the proposed incision site. A spiral pattern should make increasing circles toward the edge of the shaved area. Once a sponge has traveled over an area, it should not touch that area again. The alcohol or saline sponge is then placed over the incision site and the spiral pattern is repeated. The whole procedure is repeated twice more, with fresh sponges at each step, and a sterile gauze sponge is placed over the incision. The animal is then transported to the surgical suite, positioned, and tied to the surgical table and the surgical scrub is performed.
The sterile surgical scrub should be performed wearing sterile gloves, cap, and mask to reduce the potential for contamination of both the patient and the surgical suite. The technique is the same as for the preliminary scrub (three alternating scrubs) except that timing is critical when using povidone-iodine. The contact time for iodophors should be at least 5 minutes.
In some cases, the veterinarian may request a one-step prep, which may be painted on the area and left there without performing the alternating scrub. Some veterinarians may prefer that the one-step prep be painted only on the incision site itself, after the alternating sterile surgical scrubs. Preliminary scrubbing should always be performed to remove dirt and oils that might interfere with the action of the one-step prep formulas.

Draping
The drape has a number of functions. It can absorb bodily fluids such as blood and increases the size of the sterile field. It also prevents contamination of the surgeon's hands and instruments. Draping should only be performed by the surgeon or a surgical assistant in proper surgical attire (see Preoperative Preparation of the Veterinarian and the Surgical Assistant) in order to maintain asepsis. The anesthetist or the nonsterile assistant should open the outer covering of the pack on the Mayo stand. The surgical assistant will then open the second wrap and prepare to drape the animal. In general, there should be four huck towels and a sterile drape within the pack. The four huck towels should be applied first in an overlapping rectangular pattern. They will be clipped to the patient using towel clamps which should be tucked under the towels to prevent possible contamination. Towel clamps are considered contaminated once they have penetrated the skin. The sterile drape is placed over the towels. The drape may be fenestrated (meaning it has a hole in it) or it may be an adhesive plastic or paper drape that requires cutting in the shape of the incision.

Maintenance of the Surgical Field
Once the pack is open and the surgical drape is in place, aseptic protocol should be in place in the surgery room. In order to prevent contamination, everyone in the surgical suite, including the anesthetist and any other personnel, should have a cap, mask, and booties. Someone may be designated to leave the surgical suite to retrieve missing instruments and other items; that individual will be less sterile than the core operating team.
Excessive movement and noise should be avoided in the surgery, and nonsterile items should be kept away from everything in the sterile field. The sterile field is a sphere that includes the portion of the animal that is draped, the front of the surgeon and the surgical assistant, the Mayo stand and pack, and anything else that has been sterilized and prepared for surgery. The surgeon and the surgical assistant should not turn their backs on the sterile field and should keep their hands between waist and shoulder height to prevent contamination.
Extra items needed during surgery should be opened by the nonsterile assistant. The exterior wrap of the pack should be opened carefully and the surgical assistant or the veterinarian can then lift the material from the opened pack. If an envelope pack of suture or a scalpel blade is needed, the nonsterile assistant should open the wrapper with both hands so the veterinarian or the surgical assistant can remove it from the wrapper with a pair of needle holders or forceps.

Preoperative Preparation of the Veterinarian and the Surgical Assistant
Anyone in close proximity to the surgical site must be properly prepped for surgery including proper attire, scrubbing of the hands and arms, gloving, and gowning. This will help to prevent contamination of the surgical site. Another value of the ritual of surgical preparation is increased awareness of asepsis and focus on the patient. The time required to prepare for the surgical procedure is often used for mental preparation by the surgeon and the team.
Proper attire includes surgical scrub pants and top, a surgical bonnet or cap, a mask, and booties. These items must be worn during scrubbing, gowning, and gloving as well as during the surgical procedure itself. Booties should be removed prior to leaving the surgical suite. Technicians and surgeons should not have acrylic nails and should keep their nails trimmed short. Nails are a great place for bacteria to hide. Acrylic nails are porous, allowing bacteria and fungi to colonize between the acrylic and the nail. The same is true for nail polish. For the purposes of the following sections on scrubbing, gowning, and gloving, the term surgeon will be used to describe any person in the aseptic field of the patient.

Scrubbing
The surgical hand scrub removes dirt and oils that have accumulated on the hands. Any dirt or oil can carry bacteria into the surgical site. Gloves often have tiny holes and should not be relied upon for sterility. Although their surfaces are sterile, any holes in the gloves may allow moisture to wick bacteria from the hands into the incision. Once scrubbing begins, the hands should be kept above the waist and below the shoulders and that person is considered clean and must avoid contamination. If the forearms or hands come into contact with any nonsterile item, the scrub should be repeated.
Prior to beginning the scrub, the technician should remove all jewelry, open the gown and glove packs, and don the surgical cap, mask, and booties. The gown pack should contain a towel for drying the hands and arms. If it does not, a separate towel pack should be opened.

Chlorhexidine or povidone-iodine scrub may be used for the surgical hand scrub. Most sensitivity reactions are a result of povidone-iodine scrub, but have also been reported with chlorhexidine, so any redness or irritation should be monitored.
During the scrubbing procedure, the hands should always be kept higher than the elbows. Soap and water should be allowed to drip into the scrub sink from the elbows. The first step in the scrub procedure is wetting down the hands and forearms. Water helps establish a better contact with the scrub soap and increases the effectiveness of the scrub. The hand, the wrist, the forearm, and then the elbow should be run under the faucet (in that order) slowly to ensure maximum wetting. Surgical scrub is then applied to the hands and a lather is formed. A nail brush is used to scrub the nails. The nails are then cleaned with a nail cleaner to remove any debris beneath the nail. The hands are rinsed thoroughly and more surgical scrub is applied to the hands. The scrub brush is used to scrub each quadrant of each finger, each hand, each wrist, each distal forearm, and each proximal forearm. One hand and arm should be completed before the other is begun.
The quadrants are based on the anatomy of the finger. Each surface has four quadrants: medial, lateral, dorsal, and palmar. The lateral quadrant is usually the interdigital (between the fingers) area and should receive extra attention during the scrub. On the hand to the wrist, each quadrant should get 25 scrubs, and the rest of the arms should get 10 scrubs per quadrant. The contact time with the antiseptic surgical scrub should be a minimum of 5 minutes prior to rinsing.
Rinsing should be in this order: finger, dorsal surface of hand, palmar surface, wrist, forearm, elbow. Again, hands should never be below the level of the elbow. If a nonsterile surface is contacted, the procedure should be repeated starting at the beginning. The arms should be allowed to drip dry for a few seconds, then proceed to the drying step.
Drying the hands must be performed with a sterile towel. The towel is grasped at one corner and laid over the top of the opposite hand. The grasping hand dries the covered fingers, then the hand, then the wrist, then the forearm. The towel is then grasped by the dry hand, the side that was not used to dry the other hand is draped over the wet hand, and the process is repeated. The towel is then dropped onto the table or the floor for cleaning, with care taken to avoid contaminating any sterile items that may be on the surface if the towel is dropped on a table or counter.

Gowning
The surgical gown acts as a secondary sterile barrier between the surgeon and the animal. Gloves do not extend past the wrist, so an additional barrier must be used to cover the hair and skin of the forearms. Remember, hair is always considered contaminated. Even though the arms and hands are clean and disinfected, they are not considered aseptic. Gloves and gowns come out of the package sterile and if they are properly put on, the external surfaces remain sterile. Since this is the surface that comes into contact with the animal, asepsis is maintained.
Gowns may be either muslin or disposable paper. In either case, the gown should be folded in accordion pleats with the internal surface of the gown facing the surgeon assistant. The surgeon then grasps the interior of the neck (or tie strings) and brings the gown toward him or herself, allowing it to fall open by gravity. The hands are placed into the sleeves and a nonsterile assistant ties the internal ties. If the surgeon is performing closed gloving, the hands remain inside the sleeves of the gown. The surgeon can then hand the external tie to the sterile assistant who can then complete the gowning procedure and proceed to gloving. (See Gloving.)
If the surgeon is performing open gloving, the hands will come through the cuffs, with care taken not to contaminate the front of the gown. The surgeon will then proceed to gloving prior to completing gowning. Closed gloving is preferred because open gloving increases the risk of gown and glove contamination.


Gloving
Open gloving allows the surgeon to visualize the hands and guide them successfully into the glove. Closed gloving is more challenging because the surgeon cannot see the hands, but it provides increased safety.
The procedure for open gloving is performed with the hands outside of the gown cuffs. The surgeon uses the dominant hand to grasp the interior of the glove cuff (the side that touches the surgeon's skin). The nondominant hand is inserted into the glove and the cuff is pulled down to meet the cuff of the gown without flipping the cuff of the glove. The sterile side of the nondominant hand is then inserted into the cuff of the other glove (the side that touches the patient's skin) and the dominant hand is inserted into the glove. The cuff of the dominant hand glove is inverted over the cuff of the gown. The dominant hand then is used to invert the cuff of the nondominant hand glove over the gown cuff. If this has been done correctly, the only surfaces touching the animal will be sterile.
The procedure for closed gloving is a little different. In this case, the hands remain inside the cuff of the gown and are not exposed to the exterior. The glove is picked up so that the thumb is touching the thumb of the hand to be gloved through the gown, with the fingers facing the elbow along the inner surface of the arm. The edge of the cuff is grasped by the opposite hand (still through the gown) and pulled over the hand and gown cuff. The fingers are fed into the fingers of the glove and the cuff is adjusted. The procedure is repeated for the opposite hand. If done correctly, there is no chance of contamination of the external surface of the gown or gloves. This is the preferred method of gloving.
Once the gown and gloves are in place, the surgeon is considered sterile. Hands should remain above the waist and below the shoulders. They should touch no nonsterile surfaces or items. Any contamination will necessitate repeating aseptic preparation. The surgical team should now proceed from the prep room into surgery.

Intraoperative Procedures
In the surgical suite, the patient should already be prepped, with all monitoring equipment in place by the time the surgeon and surgical assistant walk into the room. This reduces the time the patient is under anesthesia and decreases the possibility of complications. Maintaining the sterile field (the area of the surgical drape and the front of the surgeon and the surgical assistant and any other equipment) is very important. Communication should be maintained between all people in the surgical suite. Any nonsterile persons who must come close to the sterile field should announce themselves and inform the surgeon where they are in relation to the field. This will help to prevent breaks in asepsis because of accidental bumping. The surgeon should also be informed of any new instruments or materials placed within the sterile field and their location.

Patient Monitoring
Patient monitoring includes anesthetic monitoring, monitoring patient vital signs, and monitoring the equipment. The veterinary technician may be the person assigned as the anesthetist, the surgical assistant, or the nonsterile assistant. In some cases, the veterinary tech may even be both anesthetist and nonsterile assistant.
The anesthetist is in charge of anesthetic and vital sign monitoring. Vital signs include temperature, pulse, respiration, and heart rate; equipment readings include pulse oximeter, ECG, capnometer, blood pressure, gas anesthetic and oxygen flow rates, and anesthetic monitoring of reflexes (palpebral, corneal, jaw tone, and withdrawal), fluid flow rate, and planes of anesthesia.
Vital signs should be taken every 5 minutes during an anesthetic procedure. Preprinted reference charts are available that allow the technician to plot the points on a graph. This helps to establish trends that can alert the technician and the veterinarian to potential problems during anesthesia. The plotted anesthesia chart should become part of the patient's permanent record after recovery. Although a number of machine monitors are available, with audible alarms and flashing lights that alert the operator to problems, no machine can take the place of excellent nursing care. A vigilant anesthetist may make the difference between a survivable complication and an anesthetic death.
The veterinarian should be informed of any dangerous trends during anesthesia. Shock symptoms (increased CRT, increased pulse rate, increased respiratory rate, decreased blood pressure) are some warning signs. Other dangerous trends include deepening plane of anesthesia past stage III and arrhythmias. The anesthetist should be familiar with the operating manuals of the various monitoring equipment available and be able to troubleshoot problems. Most anesthetic complications are due to problems with either anesthetic or oxygen flow. Therefore, the anesthetist should also be familiar with the anesthesia machine and the air-flow pattern in order to troubleshoot issues with the system. Never rely completely on a machine; instead rely on your hands, your eyes, and your brain.

Veterinarian
The veterinarian is the surgeon, pharmaceutical prescriber, and diagnostician. The surgeon will recommend the anesthetic cocktail for the procedure and any other drugs that may be required for the case. The technician should always ask the veterinarian for this information prior to the procedure. The veterinarian will also perform the procedure. During the procedure, the veterinarian may ask for additional materials or items. It is the job of the nonsterile assistant to bring materials to the sterile field (see Maintenance of the Surgical Field). The nonsterile assistant may also be given items from the sterile field for further testing (culture and sensitivity, cytology, or histopathology). Once the veterinarian has finished the procedure, the technician staff will be responsible for patient recovery

Function of the Surgical Assistant
The surgical assistant helps the veterinarian during the surgical procedure. This may involve handing instruments to the veterinarian, organizing the pack materials, counting gauze sponges (to make sure none are left inside the animal), retracting tissues within the sterile field, and acting as an extra set of eyes for the veterinarian. In some states, skin closure is within the scope of the technician practice act. Whatever their duties, surgical assistants should be in surgical attire (sterile gown and gloves, hair cover, and mask) and must remain sterile until released by the veterinarian.

Postoperative Procedures
Postoperative procedures are just as important as pre- and intraoperative procedures. The proper postoperative maintenance of equipment, instruments, and the surgical suite is just as important as patient recovery in the smooth function of a surgical facility.
Many fatal surgical complications occur during recovery and can be avoided with proper monitoring. Machine monitoring should continue until extubation, or the removal of the endotracheal tube from the animal. The patient's vital signs—TPR (temperature, pulse, and respiration), reflexes, and capillary refill time—should continue to be monitored until the animal is sternal, a sure sign of recovery. Periodic monitoring of vital signs (every 15 to 20 minutes) should continue until the animal leaves the facility.
Monitoring equipment should be inspected at least daily for proper function. Cords should be inspected, surfaces should be disinfected, and any other maintenance (such as battery changes) should be performed prior to putting the equipment away. A checklist for equipment maintenance should be maintained in the surgical suite to ensure quality control. This saves precious time during a surgical procedure. If the equipment is not functioning, the patient may not be monitored while the technician is troubleshooting or finding other equipment. This is dangerous to the patient.

Patient Recovery
The anesthetized patient is unable to control body temperature, posture, reflexes, and other biological processes, and depends on the surgeon and technicians for all of these functions. It is the technician's responsibility to maintain the patient's body temperature by using external heat sources (circulating water blankets, forced air warmers, bubble wrap, and the like) and warmed fluids. Animals recover from anesthesia much faster if they are maintained close to normal body temperature for the species. Proper body temperature assures that normal chemical reactions can occur in the animal's tissues. Reptiles should be kept within their optimum temperature zone during surgery for the same reason.
Recovering animals should be placed in normal body posture after surgery as well. An animal in lateral recumbency (lying on its side), will not be able to fully ventilate the down side of the lungs. Sternal recumbency allows both lungs to inflate fully, which will increase the rate of gas exchange (oxygen and carbon dioxide) and facilitate exhalation of anesthetic gases such as isoflurane. Discontinuing the gas anesthetic and placing the animal on 100% oxygen will also facilitate the exchange of anesthetic gases. Care must be taken to disconnect the endotracheal tube from the anesthetic machine prior to moving the animal to prevent accidentally removing the tube or damaging the trachea.
Monitoring reflexes will help to assess when the patient is ready to be extubated. In general, the first reflex to return after anesthesia is discontinued is the blink, or palpebral, reflex. The next is the withdrawal reflex and the last one is the swallow reflex. The animal should not be extubated until the swallow reflex is present. If the animal swallows twice, it is ready. Brachycephalic animals with short, broad heads, such as pugs, should be kept intubated until they begin to chew the tube. These animals have elongated soft palates, small nares (nostrils), and small tracheas, so they are already compromised. Maintaining an endotracheal tube for longer time in these animals ensures better airway maintenance during recovery.
The animal should be closely monitored until he is on his feet and walking under his own power. Recovering animals have altered states of consciousness and may have behavioral issues that they do not have when awake. They are also ataxic (unsteady) and may injure themselves during this period.

Postoperative Instrument and Equipment Care
Surgical instruments are expensive pieces of equipment. They require care and maintenance in order to perform their function properly. Surgical instruments are generally made from stainless steel. They can range in price from $14 to $1,400 for a single instrument. Improper care or mishandling can result in broken, corroded, or misshapen instruments that must be replaced.
The entire pack should be brought to the surgical prep area and broken down as soon as possible after surgery. All gauze sponges (soiled and fresh) and instruments should be counted and checked against the pack inventory. Missing sponges or instruments may be in the animal. It is best to use gauze sponges with a radio-opaque line woven in. These sponges can be seen on a routine radiograph if they are accidentally left in the animal. Stainless steel instruments will also show up on a routine radiograph. After counting, the instruments should be opened (open the ratchet or lock box) and placed in cold water to prevent sticking of debris. Another cold water bath will help to loosen blood from muslin drapes and towels.

Cleaning
Detergent is added to warm water and the instruments should have all surfaces scrubbed with a soft brush. After the initial cleaning, the instruments should be placed in an ultrasonic cleaner to remove hidden debris, and then rinsed and dried. Instruments with hinges and lock boxes should be sprayed down with lubricant surgical milk and dried again. They are now ready for the autoclave. Instruments should be sterilized with the lock boxes in the open position for all methods except dry-heat sterilization. Dry-heat sterilization sterilizes by conduction of heat which is transmitted through the body of the instrument. All other methods sterilize by surface contact.
Prior to being packed for sterilization, fabric items such as gowns, drapes, and towels should be rinsed well, then laundered separately from other clinic materials such as bedding.

Common Surgical Procedures
Many surgical procedures are considered routine in veterinary medicine because they are performed either frequently in the practice or on an elective basis. However, no surgical procedure is without risk. Any procedure requiring general anesthesia and/or entering a body cavity poses a potential danger to the patient. It is important to minimize the risks as much as possible by providing excellent nursing care and following routines in surgery that minimize mistakes. This will enable the technician to be prepared if an emergency arises and anticipate both the veterinarian's and the patient's needs.

The most common complication during a surgical procedure is shock. Excellent patient monitoring enables the technician to anticipate potential problems with shock, which is a decrease in systemic blood pressure or cardiac output. During surgery, shock can occur secondarily to hemorrhage, pain, anesthetic overdose, oxygen deprivation, or dehydration. Treatment may be as simple as turning down the anesthetic flow rate, putting the patient on 100% oxygen, increasing patient body temperature, and providing increased fluid flow rates. Drugs can also increase cardiac output or stabilize arrhythmias due to shock.
Another possible postoperative complication is wound dehiscence (separation of the wound edges). This may occur secondary to infection, traumatic injury (usually due to self-mutilation), suture reaction, or poor surgical technique. Dehiscence can occur in the internal layers or in the skin. Internal dehiscences may occasionally be referred to as incisional herniation. Prevention of infection has already been discussed in the surgical preparation section. Prevention of traumatic injury includes keeping the patient quiet and preventing excessive activity including running, jumping, or excessive play activity during the postoperative period. Since wound healing normally requires 10 to 14 days, the patient should be kept at a decreased activity level for that time period. If external sutures have been used, the animal may go back to normal activity levels after suture removal. It is good practice to recommend a recheck after 7 to 10 days to assess the animal for postoperative complications.

Suture selection can play a role in postoperative recovery. Sutures comes in various sizes from 7-0 (smallest ophthalmic suture) to 3 (large-animal suture) and are either absorbable or nonabsorbable, natural or synthetic, inert or reactive, and monofilament or braided. Absorbable suture material may be left in the patient and is made to be absorbed over time. A nonabsorbable suture may either be left in the patient or removed after healing. Inert substances (such as stainless steel) may be left within the animal because the body will not react. Reactive materials (such as some plastics) may need to be removed to prevent the body from having a foreign-body reaction (inflammation).

The ideal suture does not exist. The ideal suture would retain its strength in tissues until the tissue is completely healed, then dissolve. It would not cause foreign-body reaction and would produce minimal inflammation. It would have enough friction to hold a surgical knot without untying but would have minimum tissue drag, and it would be flexible. Because this magic suture does not exist, veterinarians develop preferences for one or more types of suture depending on their characteristics.
Natural, absorbable, reactive, monofilament suture material is surgical gut made from the submucosa of the intestines of a sheep. It is highly reactive and is broken down by inflammation and phagocytosis (neutrophils) in the animal. Because of this inflammatory reaction, it breaks down quickly (within 1 to 3 weeks) and can lead to dehiscence. On the other hand, it forms excellent knots and handles well.

Synthetic, absorbable, inert, monofilament suture material, such as PDS™ (polydiaxinone), has decreased tissue drag (as a monofilament) and retains its shape, but requires multiple throws to maintain knot strength. It maintains its strength for 2 to 4 weeks in tissues and will actually remain in the tissues for 6 months before breaking down completely. Maxon™ (polyglyconate) has similar characteristics to PDS. Monocryl™ (polyglecaprone) is a monofilament that breaks down quickly (like gut), but does not cause the intense reaction of gut. It does not have the strength of the other synthetic monofilaments. Monocryl Plus™ is a coated monofilament that decreases the bacterial colonization. Biosyn™ (glycomer 631) is similar in use to Monocryl and breaks down quickly, but has the strength of Maxon and PDS.

Natural, nonabsorbable, reactive, braided suture material, such as silk, is made from the cocoon of the silkworm. It is strong and has excellent handling characteristics including knot holding. On the other hand, it causes severe tissue reaction and can act as a wick for bacterial contamination. It usually degenerates after 6 months in the body. Cotton and linen have similar characteristics to silk, but are rarely used in veterinary medicine.
Synthetic, nonabsorbable, inert, braided suture material, such as polyester, has good handling ability, but has increased tissue drag and knots tend to slip. It tends to wick bacteria. Polymerized caprolactam (Braunamid™ or Supramid™) is similar to polyester in characteristics, but is coated to reduce tissue drag. It will also wick bacteria.
Synthetic, nonabsorbable, inert, monofilament suture material, such as stainless steel, does not support bacterial growth and retains its strength even in the face of severe tissue reaction due to infection. On the other hand, it does not handle well and tends to kink. Nylon (polyamide) comes in both monofilament and braided forms. While it does not cause tissue reaction, it does not handle well (knots can slip). There is little chance of wicking. Prolene™ (polypropylene) is similar to nylon but maintains its strength for longer periods of time. Novafil™ (polybutester) is also similar to nylon, but has significant stretch; it is commonly used for ligament and tendon surgeries.
Synthetic, absorbable, inert, braided suture material, such as Dexon™ (polyglycolic acid), has excellent handling characteristics (knot tying and holding) and good initial strength, but it breaks down rapidly in tissues (1 to 2 weeks). It has increased tissue drag and can cause bacterial wicking if used as an external suture. Vicryl™ (polyglactin 910) is a coated suture material that has similar characteristics to Dexon. Polysorb™ (glycolside-lactide copolymer) is another suture material similar to Dexon.

Small Animals
Surgeries are more commonly performed on small animals (dogs and cats) than on large animals. Although surgical procedures ranging from open heart surgery to limb amputation are seen in veterinary practices, elective surgeries are the most frequently performed. An elective surgery is one that is not essential to maintaining the life or function of the animal and may be scheduled at the owner's or the veterinarian's convenience. A nonelective surgery is one that must be performed as quickly as possible to maintain the life or function of the animal. Elective surgeries may also be performed as nonelective procedures in certain circumstances. This will be discussed more thoroughly in the following sections.

Ovariohysterectomy
The ovariohysterectomy (OHE), more commonly known as spaying, is the most common elective procedure in female dogs and cats. The procedure requires complete removal of the uterus and the ovaries and is performed electively as a means of preventing pregnancy or on a nonelective basis to treat such diseases as pyometra (infected uterus), dystocia (difficult birth), ovarian cysts, or uterine or ovarian neoplasia. Dogs spayed prior to 6 months of age have a much lower incidence of mammary cancer later in life. If possible, the bitch should be in anestrus or between 4 and 6 months of age to minimize the size of the uterus and uterine blood supply.
Because this is an abdominal surgery, postoperative pain control should be considered.

Instrumentation
A full surgical pack including 4 towels, a drape, a spay hook, several hemostatic and Kelly forceps, a pair of needle holders, scalpel blade handle, tissue forceps, towel clamps, scissors (surgical, Mayo, and Metzenbaum), and multiple sterile gauze sponges should be prepared. A #10 scalpel blade, several types of suture material (of the veterinarian's preference), and additional gauze sponges in a separate pack should also be available if needed. For a nonelective spay, additional clamps, bowls, retractors, and saline flush may be needed.

Technique
The ventral midline of the animal is prepared as stated in the section on Preoperative Preparation. The incision will be along the ventral midline somewhere between the umbilicus and the pubis, so the shaved area should be from approximately 2 cm above the umbilicus to the pubis. Veterinarians differ as to the size of the incision they prefer, but the initial cut is usually 1 to 2 cm below the umbilicus and extends caudally. In cases of a nonelective spay, the incision may be much larger and extend farther cranially, requiring a larger area to be shaved and prepped. The surgical prep is performed by the nonsterile assistant.
Once the animal is prepped, towels are placed in a square around the proposed incision and a sterile drape is placed. These two steps must be performed by the sterile assistant or the veterinarian. Once the animal is draped, the veterinarian begins the procedure. The skin is incised first, then the subcutaneous fat, then the abdomen is penetrated by incising the linea alba. The linea alba is an aponeurosis (fascia connection) between the two sides of the abdominal musculature. The peritoneum is the internal layer of the linea alba. This is the same approach used for an exploratory laparotomy or any other abdominal surgery. For cranial abdominal surgeries, such as gastrotomy (stomach surgery), liver, or spleen, the incision will extend cranially to the umbilicus.

Once the abdomen has been entered, the uterine horns are located and exteriorized. The ovaries are located and a clamp is placed on the connective tissue between the ovary and the uterine horn and over the ovarian artery/vein stump. The ovarian blood vessels are then ligated (tied off with suture), and cut above the suture. The suspensory ligament between the ovary and the crus of the diaphragm may need to be separated in order to exteriorize the ovary. The other uterine horn is located and the procedure is repeated.

Once both ovarian stumps are ligated, the clamps should be removed and assessed for bleeding. Bleeding stumps should be reclamped and religated. The uterine horns are followed caudally to the uterine body, which is clamped and double ligated. The clamps are removed and the uterine stump is again assessed for bleeding.

The incision is closed beginning at the muscle layer in a simple interrupted pattern. The subcutaneous and cutaneous tissues may be closed in a variety of patterns, but should be closed separately from each other. External sutures may also be used. These should be removed 10 to 14 days after surgery. In most states, it is within the technician's scope of practice to perform skin closures. The most common skin closure is the simple interrupted pattern.
Possible complications include hemorrhage of the ovarian or uterine stumps; ligation of the ureter, which can cause renal failure; and dehiscence.

Orchidectomy
Orchidectomy, more commonly known as neutering or castration, is the second most common elective surgical procedure in small animals. This is the complete removal of the testicles. Advantages to orchidectomy are numerous: prevention of pregnancy, prevention of testicular cancers, prostatic hypertrophy/prostatitis and perianal adenomas, decreased roaming behaviors, possible decreased aggression, and decreased urine odor in cats. The procedure may be performed at any time, although, in cats, castration at 6 to 7 months of age may prevent urine spraying and fighting due to testosterone. Nonelective orchidectomy may be performed in animals with testicular tumors (most of which are benign), perianal adenomas, or prostatic problems. Removal of the hormones that lead to these problems may result in complete resolution of symptoms.
Both testicles must be removed. Cryptorchid (hidden or retained testicle) animals may have the testicle in the inguinal canal or in the abdominal cavity. Such animals require an abdominal approach to remove the hidden testicle (cryptorchidectomy). Retained testicles have a higher incidence of testicular cancer than scrotal testicles and should be removed.
The canine neuter requires a full surgical pack including a scalpel handle, thumb forceps, hemostatic forceps and Kelly forceps, a needle holder, and scissors (surgical and Mayo). Full draping (including towels, towel clamp, and drape) is generally performed. A #10 scalpel blade and absorbable suture material are generally used.
The feline neuter requires only a scalpel handle, thumb forceps, and hemostatic forceps. Although this is performed using aseptic technique, the area is rarely draped prior to the incision. A #10 scalpel blade is used. Absorbable suture may be used in some cases.

Technique in the Canine
The anesthetized dog should be placed in dorsal recumbency in a frog-legged position. Preparation for the canine neuter involves shaving the prepuce, inguinal, and prescrotal areas with a #40 clipper blade. The veterinarian may prefer not to shave the scrotum itself to prevent irritation and clipper burns that may increase self-mutilation after surgery. The prescrotal area and scrotum is then prepped as previously with alternating scrubs, toweled in with towel clamps, and draped. The veterinarian pushes the testicle into the prescrotal area and makes an incision through the prescrotal skin on the midline over the displaced testicle. The testicle is exteriorized through the incision and an incision is made through the vaginal tunic encasing the testicle. The testicle, testicular artery, vas deferens, and pampiniform plexus can then be visualized, clamped, and ligated. The testicular artery, pampiniform plexus, and vas deferens are then cut between the clamp and the testicle is removed. The stump is then examined for bleeding, and the procedure is repeated on the other side. Simple closure of the subcutaneous and skin is all that is needed. This procedure is called an open castration because the vaginal tunics are opened and the testicle and blood vessels are visualized.
Closed castration means that the vaginal tunics remain closed. In this type of castration, the covered testicle and blood vessels are exteriorized and a clamp is placed. A suture ligature is placed around the entire stalk and the entire structure is cut and examined for hemorrhage. The advantage of the closed castration is that it maintains the integrity of the inguinal canal. Incorrect ligation of the blood vessels in a closed castration may cause severe abdominal hemorrhage and should be corrected if it occurs. Closure is the same as for the open procedure.
In cases of cryptorchid testicles, an abdominal approach is needed. The abdominal approach requires a skin incision made around one side of the penis and prepuce. Once the skin has been incised, a ventral midline approach through the linea alba is made. The vas deferens and pampiniform plexus are located, clamped, and ligated and the testicle is removed. The muscle layer and skin are closed as described in the ovariohysterectomy section.

Technique in the Feline
The anesthetized cat is generally placed in either lateral recumbency or dorsal recumbency with the legs forward depending on the preference of the veterinarian. The hair is generally plucked from the scrotum by pulling the hair with the pad of the thumb and index finger until all hair has been removed. Shaving will generally cause more irritation than plucking and should be avoided. The area is aseptically prepared with alternating scrubs. The surgeon should wear surgical gloves and a gown. A. incision is made directly into the scrotum and the testicle is exteriorized. An incision is made through the vaginal tunic and the blood vessels are clamped and ligated. Another technique is to tie the entire cord in a knot, or to separate the pampiniform plexus and vas deferens and tie them together in a square knot. The last two techniques avoid possible suture reaction at the site, but may increase the chance of hemorrhage. The stumps of the blood vessels are allowed to retract within the tunic and the incisions are left to drain without suturing.
Complications of feline orchidectomy include hemorrhage, swelling, and self-mutilation. Elizabethan collars and proper preparation of the area may reduce the incidence of self-mutilation and checking stumps prior to leaving surgery will reduce the incidence of hemorrhage and swelling.

Onychectomy
Onychectomy, or declawing, is the removal of the claw and the associated third phalanx. This is an amputation. There are many different techniques for this procedure. The veterinarian will use whatever technique he or she has been trained to perform. This procedure is very painful for the cat, and owners should be made aware of this prior to having their pets undergo the procedure. In some countries, declaws are no longer allowed because of the pain involved. Many veterinarians recommend only declawing the front feet because the cat will still be able to defend itself and might be able to still climb trees if it still has rear claws.
Although the onychectomy is painful and may seem barbaric, it has its place. It will prevent destruction of furniture and can decrease injury to children, the elderly, and immunosuppressed or diabetic people. Cats that might otherwise need to be relinquished to the humane society may be kept in a home if they are declawed

Cats have a retractable third phalanx to which the claw is attached. The musculature allows retraction of the claw into a sheath of skin rather like a switchblade when it is at rest (this actually puts the joint in extension). The extension of the claw occurs through action of the deep digital flexor tendon on the ventral side of the phalanx. The only feline that does not have retractable claws is the cheetah. Cats do not walk on the third phalanx, so removal should not affect ambulation (the ability to walk). Dogs use their third phalanx and claws to ambulate, so declaw should never be performed in canines unless medically necessary.
Instrumentation for onychectomy is as varied as the techniques used. In general, a scalpel blade (either #11, #12, or #10 blade depending on preference), a blade handle, and a pair of Kelly or Carmault forceps or towel clamps are used. In some cases, a pair of guillotine nail trimmers may be used instead of the scalpel blade and forceps. Some practices use a laser to cut the tissues. Laser surgery may decrease bleeding and postoperative swelling.
The feet are prepped using alternating scrubs of chlorhexidine and alcohol. Long-haired cats should always be clipped, but some surgeons prefer leaving the feet unshaved to reduce postoperative inflammation and pruritis.
A ring block using Lidocaine with epinephrine should be placed at the carpus or tarsus. The block should begin at the lateral styloid process of the ulna/lateral malleolus, medially at the radial insertion/medial malleolus, then at the carpal or tarsal pad. All blocks should be in place a minimum of 5 minutes prior to the first incision to allow maximal efficacy of pain control. The ring block should be effective in controlling intraoperative and postoperative pain for a few hours and preventing wind-up.
A tourniquet is then placed at the elbow or the tarsus and the forceps are used to grasp the toenail or claw and extend it fully from the sheath. Incision is made on the dorsal surface of the claw proximal to the third phalanx, cutting through the lateral collateral ligaments, the extensor tendon, and the digital flexor tendon. The entire third phalanx must be removed to prevent regrowth of the claw. Care should be taken not to cut through the digital pad because that would interfere with healing.
Once the claw has been removed, the resulting hole should be checked and the skin closed with surgical glue such as Nexaband®. The procedure should be repeated on all five claws on the front feet (four claws on the rear). The foot should then be bandaged with gauze sponges and surgical tape or vet wrap and the tourniquet removed.
Postoperative pain control is a must after onchyectomy even though regional nerve blocks have been used. Opiates such as buprenorphine provide excellent analgesia. Some veterinarians use a single dose of the NSAID meloxicam prior to surgery. This will last 24 to 30 hours postoperatively for pain control. Clay and clumping litter should be avoided. Newspaper litter is safer in these cases.
Complications of onchyectomy include hemorrhage, infection, and dehiscence.

Caudectomy and Dewclaw Removal
Caudectomy, or tail dock, and dewclaw removal are often performed on purebred puppies from breeds for which the AKC recommends specific tail length and no front or rear dewclaws. Terriers, corgis, and other breeds are subject to those standards. The veterinarian and technician must be sure to consult the AKC and the owner about the desired length of the tail, especially in show animals. Incorrect tail length may disqualify the animal. These procedures are usually performed 2 to 3 days after birth without general anesthesia. Local anesthesia may be used for the caudectomy procedure.
A pair of Mayo scissors and a pair of mosquito forceps along with needle holders and absorbable suture are usually all that is required for these procedures.
The puppy is held with the tail up and the ventral side facing the surgeon. The feet are restrained. The tail is prepped with alternating surgical scrubs and the veterinarian grasps the tail to reduce blood flow, counts the required number of vertebrae and cuts the tail with the Mayo scissors distal to that point. Sutures are then placed in the skin to cover the stump. Sutures are generally clipped short to prevent the dam from removing them while grooming the pup.
The puppy is then flipped on its side and each individual leg is restrained to give the veterinarian access to the dewclaws. Each dewclaw is grasped at the base (proximal to the pad) with a pair of mosquito forceps and twisted to remove the dewclaw or cut with scissors. Any remaining piece of bone from the dewclaw should also be removed to prevent regrowth. The resulting skin defect should then be sutured.
The major complication with this procedure is wound dehiscence from overgrooming by the dam. This may result in excessive scarring or even keloid formation.

Large Animals
Many large-animal procedures are performed with the animal either awake or in twilight or standing anesthesia with a local anesthetic. Putting a large animal under general anesthesia requires specialized instrumentation such as a lift table. General anesthesia has many risks for large animals, including bloat in ruminants (cattle, goats, and sheep), broken limbs in horses (during recovery and induction), myositis and myoglobinuria (in all large animals), and malignant hyperthermia in pigs.
If a large animal is to be placed under general anesthesia, an entire team and a great deal of preparation are needed to prevent injury to the animal, the veterinarian, and the rest of the team. The induction area must be free of protrusions that can injure the animal, the room should be thickly padded, and the animal's hooves should be wrapped in tape to prevent self-injury.
Horses and pigs are generally intubated prior to surgery. A 12-hour preoperative fast will help to empty stomach contents and prevent aspiration in pigs. In horses, vomiting does not occur, but a 12-hour fast will make respiration easier by emptying the stomach. In ruminants, a 24- to 30-hour fast may be needed prior to surgery to empty out the stomach. A nasogastric tube may be inserted to prevent gas bloat in these animals.
Although general anesthesia is rare in ruminants, sheep and goats are commonly used as research animals and may require general anesthesia for certain procedures. General anesthesia is far more common in equines for orthopedic injuries and colic surgeries. The techniques covered in this section will focus on procedures performed in general practice, not at equine surgical specialty centers.

Orchidectomy (Gelding or Castration)
This procedure is usually performed in the field either as a standing procedure or in lateral recumbency. This is the most common procedure in the horse. Cryptorchids can also be castrated as a standing procedure through the inguinal canal. Technicians usually participate in surgical prep, anesthesia, and animal restraint.
The instrumentation required for castration is minimal. A scalpel blade handle and a #10 blade and an emasculator are often all that is needed for horse castrations. The veterinarian should have sterile surgical gloves with sleeves.
For ruminant castration, the same instruments are generally needed.
For standing castration, the horse is heavily sedated and the scrotum and inguinal cord are injected with local anesthetic. The scrotum is incised over the testicles, the testicles are pulled through the opening, and an emasculator is placed around the spermatic cord. It is important to orient the emasculator properly so that the cord is cut distal to the crush. In common parlance, it should go nut-to-nut which means that the side of the emasculator with the nut on it should be closest to the testicle. The incisions are left open to drain and the horse is put on stall rest for 24 hours, then on minimal exercise for 3 to 4 days.
If the animal is to be under general anesthesia, it should be placed in lateral recumbency with the upper leg pulled forward to expose the scrotum. The procedure is otherwise the same.
Ruminants generally are done as standing castrations. They are restrained in a squeeze chute and the scrotum and spermatic cord are injected with local anesthetic. The scrotum is incised circumferentially and the emasculator is used in the same fashion. The incision is allowed to drain.

Caslick's Procedure
Caslick's procedure is the most commonly performed procedure in female horses. Many thoroughbreds have insufficient vaginas, which means that the vulva extends too far dorsally. This can result in air and feces entering the vagina, which can lead to infection. Caslick's procedure will prevent that from occurring by decreasing the length of the vulvar slit.
The instrumentation required is fairly minimal and includes a scalpel blade holder, a #10 blade, a pair of thumb forceps, and a pair of Mayo scissors.
The tail is diverted to one side and the vulva is prepped aseptically. The veterinarian wears sterile surgical gloves. The horse is sedated and local anesthetic is infiltrated into the lips of the vulva. The dorsal vulva is incised on both sides by the veterinarian and the freshened edges are sutured together to shorten the length of the slit using a continuous suture pattern.