• Principles of Operative Technique - Proper surgical technique is important to prevent wound infection, promote wound healing, and ensure likelihood of a satisfactory outcome to the surgical procedure.

• “Good Surgical Technique” Includes:

• Asepsis, Asepsis, Asepsis  -  Aseptic technique is required at all times and all team members are responsible for monitoring for breaks in aseptic technique. "Asepsis is a chain which is only as strong as its weakest link." Potential sources of contamination include the team members, the patient, all articles used in the procedure, the surgical room or area, and other personnel entering the surgical area.

• Gentle tissue handling -  Gentle handling of tissues will help minimize postsurgical pain. Tissues should not be cut or separated without reason and tissue dissection is usually done along fascial planes. Exposed tissue must be protected from drying or contamination.

• Effective hemostasis & maintenance of sufficient blood supply to tissues - allows visualization of the surgical field while preserving the total blood volume. Hemostasis is achieved by ligation, pressure, electrocoagulation and avoiding damage to major vessels. Only the vessel to be occluded should be incorporated in a ligature or clip. In using electrocoagulation, a high frequency current is applied to a small area of tissue (the bleeding vessel) and electric energy is converted to heat, resulting in coagulation of tissue and sealing of the vessel. To avoid excessive tissue damage, only the vessel to be occluded is in contact with the electrode. Electrocoagulation can be used for minor hemorrhage; large vessels should be ligated.

• Proper use of surgical instruments minimizes trauma. For example, vascular forceps are used to occlude blood vessels when flow is to be reestablished; hemostatic forceps, which crush, are applied to vessels through which blood will no longer flow.

• Accurate tissue apposition enhances healing and promotes rapid return to normal function. Retraction and dissection of tissue can produce pockets known as dead space. Dead space can delay healing and serve as a site for bacterial growth and fluid accumulation. As tissues are returned to their normal positions, dead space needs to be obliterated by careful suture placement to appose tissue and/or placement of drains to prevent fluid accumulation.

As a procedure is concluded, tissues are replaced to their normal anatomic positions. Most tissues should be apposed with minimal amount of tension and sutures must not devitalize the tissue in which they are placed. Type of suture material and pattern to be used will be dictated by the tissue involved and forces applied to those tissues.     

Behavior of animals also might influence the choices; some animals are more prone to chew or remove certain types of suture materials or devices such as surgical staples. Because physicians normally work with cooperative human patients, they must re-evaluate surgical materials and methods to be used with animals.

• Intraoperative patient support and monitoring - Appropriate use of monitoring equipment –  Accepted medical and veterinary surgical practice requires assessment of the physiologic status of the animal on a regular basis. Vital time for resuscitation can be lost by failure to notice life-threatening physiologic or metabolic problems.

The degree of monitoring sophistication depends on the species, the extent and duration of the surgical procedure, and whether it is a survival or terminal procedure. Monitoring can be qualitative, using the anesthetist's sense of touch, sight and hearing to evaluate the patient; or quantitative, using instruments for periodic measurement of specific vital organ performance.

The anesthetic record provides a detailed ac-count of the course of anesthesia and intraoperative events, Blank record forms are available from University Animal Care. Whether you use one of these forms, or one of your own design, it is important to record data from the pre-operative period, the induction period, the anesthetic/surgical period and the immediate post-operative period. Later measurements may be written on the individual animal's chart.

• Support of vital organ functions is an integral part of any surgical protocol.

Many devices are available but they may not be practical or applicable for all species. 

Body temperature can be measured via rectal or esophageal thermometers. Every effort should be made to combat hypothermia by use of circulating warm water blankets, warm water bottles, heat lamps, or application of insulating materials such as drapes.

Support for the respiratory system can be as simple as appropriate positioning of the animal to ensure an unobstructed airway, endotracheal intubation, or providing supplemental oxygen. A variety of techniques exist to assess cardiovascular function: capillary refill time, heart rate monitoring, Doppler Flow probes, EKG, palpation of pulse, and use of esophageal or conventional stethoscopes. Cardiovascular support includes fluid therapy and use of defibrillators and cardioactive drugs.

Monitoring rate and amount of urine production, as well as subjective assessment of blood loss, and capillary refill time of the oral mucus membranes can indicate adequacy of fluid volume. There are many possible choices for fluid replacement, but normal (0.9%) saline or balanced electrolyte solutions such as lactated Ringer's are common. Intravenous (IV) administered fluid therapy is best for larger animal species, but can be difficult in smaller animals; subcutaneous (SQ) or intraperitoneal (IP) fluids may be appropriate for these species. Warming fluids may be helpful.

• Expeditious performance of the surgical procedure implies that the surgical team will have sufficient training and competence to perform the surgical procedure in the least required amount of time. A rapid response to unplanned or emergency situations is the result of good organization and coordination of team members.  

• Maintaining a Sterile Field

Sterile Personnel - are only allowed to handle sterile objects.  If they accidentally touch an item that is not sterile they will need to stop immediately and change their gloves. Non-sterile Personnel - are not able to handle any sterile objects.  If they do the items are no longer considered sterile and must be removed from the sterile field. The outer layer of packs are not considered sterile.  A non-sterile person is able to open the package and present it to the surgeon without compromising the sterile object inside.

• Proper Draping of the Animal

• A drape is placed on the animal to maintain sterility. The area over the incision site is removed by the surgeon to expose the skin surface where the incision will be made.

• Wound Closures

• There are several types of wound closure. The type of animal and problems that will occur with certain stitches must be considered.   Multiple layers of sutures placed in a simple interrupted pattern are preferred to a continuous pattern to minimize the risk of dehiscence.  A subcuticular suture pattern is advantageous for skin closure in animals that are inclined to chew or otherwise remove stitches.  

C.  Post-operative Care

Involves observations and administration of therapeutic measures that tend to promote recovery from anesthesia and/or surgical manipulations.  These measures should minimize pain and distress.  The postoperative period consists of 3 overlapping phases: anesthetic recovery, acute and long-term postoperative care. Adequate postoperative care enhances the animal's recovery by improving it's physiologic status and minimizing pain and distress.

• The Recovery Period - is the critical time because it is a period of physiologic disturbance during which crises can arise. Frequent observation and monitoring is required.

• Recovery/rodents/large animals

• The endotracheal tube should not be removed until the animal is exhibiting an active swallowing reflex.  Maintain a clear and unobstructed airway!

• Dogs:  the neck is extended and the tongue gently pulled out of one side of the mouth.

• In most instances, animals should be frequently turned from side to side to avoid dependent pulmonary edema. 

• Antibiotics

• Analgesics – as per protocol, and veterinary recommendations

• Observations

• Record Keeping

• Vitals Signs Monitoring

• Monitor heart rate -  Cardiovascular function can be assessed by EKG, blood pressure monitors, auscultation, and evaluation of mucous membrane color.

• Monitor respiration - Respiratory function can be evaluated by mucous membrane and tongue color and respiratory volume and rate. Some situations may require a pulse oximeter.

• Check body temperature/ touch/ thermometer -  Body temperature needs to be maintained. If circulating warm water heating devices or heat lamps are used, care should be taken to ensure that animals do not chew these devices and electrocute themselves.

• Check mucus membranes for healthy pink color

• Check for signs of normal body movement - To prevent drowning or aspiration, water and food is withheld.

• Rodent Recovery:

Never recover an animal on bedding.  The animal can suffocate by inhalation of bedding through the nose or mouth.  Bedding can also get in the eyes and cause irritation or damage. A towel should be placed on the bottom of the cage along with a heat source such as heating lamp or heating pad to prevent hypothermia.  Place your hand over or under the animal, depending on your heat source, to verify that the animal is not receiving too much heat therefore preventing hyperthermia.

• Monitoring:  Turn the animal from one side to the other every half an hour to help maintain proper circulation, respiration, prevent nerve damage, and to help stimulate normal body movements .

• Recovered:  When the rodent is ambulatory, place animal back in a pan on its normal type of bedding.

• Large Animal Recovery     

Large animals can be recovered in heated cages or on the floor of a cage on a mat with a sheet or blanket. When the large animal is ambulatory, place it back in its room or cage Regurgitation associated with the movement of the rumen may be avoided by not moving the animal more than necessary.

• Long term postoperative care requires careful observation of body temperature, food intake, locomotion, behavior, and signs indicating pain. For warm-blooded species "higher" than rodents, notes must be maintained in an individual animal record and each entry should be dated and initialed.

Research staff must daily examine the surgical site, monitor for signs of infection, and remove sutures or other devices at the correct time (generally 7-10 days). The surgical site should be observed for signs of infection, incision breakdown (dehiscence), or self-inflicted trauma. At least once a day, catheters should be examined and may need to be cleaned and flushed. Drains, collars, and dressings should be examined daily and changed as needed. Bandages, Elizabethan collars and restraint devices may help prevent self-mutilation; but staff must watch that the animal can obtain food and water and move about to perform bodily functions.

Monitoring food and water intake is important to successful recovery. Oral or parenteral supplementation may be necessary to maintain normal hydration and anabolic state. Special diets may be indicated during the recovery period. The quantity and character of urine and feces should be monitored, because changes could indicate complications such as paralytic ileus, acute renal failure, or intestinal hypermotility caused by irritation.

Pain control (Analgesics) Analgesics are given to patients according to the dosage stated in the protocol and also as need during daily assessment.   Controlling Pain & Distress in Laboratory Animals

Record keeping

Daily Observations and Record Keeping - All post-surgical care provided must be documented.  Daily notes recording the animal’s progress, administration of medications and management of surgical incisions up to the time of suture removal should be written in the clinical records.  These permanent records must be complete, current, and readily accessible.   

Euthanasia  (Must follow the current AVMA Panel on Euthanasia)

Rodents

• Injections: Intraperitoneal injection of barbiturates is acceptable for small rodents.
• Inhalant: Rodents and other small animals are placed in a closed, often transparent vessel which usually contains a gas such as CO2 .  Exposure must be maintained for at least 10 minutes to ensure that the animals do not revive when again exposed to room air.
• Cervical dislocation: for mice and rats, a rod the diameter of a pencil is pressed horizontally across the spinal cord at the base of the skull.  With the other hand, the base of the tail or hind limbs are quickly pulled, causing separation of the cervical  vertebrae from the skull.  Special training is required.
• You must verify that the animal is dead before disposal

Non-Rodents

• Injectable Chemicals:  intravenous injection of a barbituric acid derivative, such as pentobarbital, is the preferred method for euthanatizing dogs, cats, and other animals that have readily accessible veins of a reasonable size.
• You must verify that the animal is dead before disposal.

Disposition:   All animal remains should be returned to the designated cooler(s) in University Animal Care facilities. Never place more than one large animal in a barrel and the total weight per barrel must be less than fifty (50) pounds. Animals exposed to biohazardous materials involve special care (radioisotopes in yellow bags and carcinogens in red bags). Never put animal remains in laboratory trashcans or outside dumpsters

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