Surgery of Exotic Animals. Группа авторов

exotic animals are more likely to develop SSI than domestic animals because their housing often require them to be in proximity to their urine and feces. Prepare an appropriate area around the proposed surgical incision. Some species like chinchillas and rabbits have fragile skin that can easily be damaged during clipping for surgery. For most mammals, a No. 40 clipper blade is used; however, in patients with very fine fur a No. 50 clipper blade (Oster Professional Products, McMinnville, TN) is better suited. The teeth of the No. 50 blade are closer together than those of the No. 40, making it more difficult for the patient's skin to get caught between the teeth and be cut. Move slowly over the skin and keep the skin in front of the clipper blade flattened. Clean and lubricate the blade frequently to help decrease the risk of damaging the skin.

Figure 1.1 The surgeon must adhere to proper aseptic technique wearing clean scrubs (a). A cap, mask, and shoe covers, and sterile gown and gloves are proper attire regardless of the size and species of the patient (b).

      In birds, it is best to pluck feathers which then regrow rapidly; however, it is best not to pluck primary flight and tail feathers as this can damage the follicle resulting in abnormal feather growth. Some birds, such as penguins, have very small dense feathers that are very difficult to pluck. Use a No. 10 clipper blade for these birds. The No. 10 blade teeth are farther apart and clip the feathers at the base. Cut or clipped feathers will not be replaced until the shaft is molted and replaced naturally.

      For many years, it has been suggested that alcohol be avoided for skin preparation of small patients because evaporative cooling might cause clinically important hypothermia. A study in mice compared the effect of skin preparation on hypothermia (Skorupski et al. 2017). They compared alcohol alone, povidone iodine alone, povidone iodine alternating with alcohol or saline or warmed saline. Alcohol alone or alternating with povidone iodine caused a dramatic drop in surface and core temperatures, but it rebounded quickly. When alcohol was used alone, the these temperatures returned to nearly the level of the control animals within minutes; however, when alternating with povidone iodine, this was not observed to occur. The authors theorized that the alcohol evaporates very quickly and the cooling stops, whereas povidone iodine and saline evaporate over a longer period of time resulting in more profound hypothermia. Using warmed saline did not modify this effect. The coldest core temperatures were observed in all povidone iodine treatment groups, and this hypothermia persisted. The authors suggested the povidone iodine takes longer to evaporate than saline, resulting in these low body temperatures. The authors concluded that using alcohol for rodent aseptic preparation causes less hypothermia and should be encouraged.

      In that study, three applications alternating povidone iodine with either saline or alcohol was used. In veterinary, surgery tradition has been to apply alternating patient skin preparation solutions such as povidone iodine or chlorhexidine alternating with alcohol or saline. The author has been unable to find any scientific evidence for this protocol. It is not applied to humans where a single application of a skin preparation solution is applied prior to making an incision. In fact, the instructions for use on the stock bottle of chlorhexidine indicate to apply the solution and allow it to remain in place for two minutes, then wipe it off and be done.

      In another study, an alcohol‐based skin preparation was compared to chlorhexidine for reducing skin surface bacteria (Maxwell et al. 2018). The alcohol‐based skin preparation sprayed onto the surgical site and allowed to dry was equally as effective as chlorhexidine used according to manufacturer instructions. Make sure the alcohol has completely evaporated prior to using electrosurgery or a CO₂ laser that can ignite the alcohol.

      It is not necessary to scrub the patient's skin and actually may be contraindicated. Scrubbing not only irritates the skin, but it also exposes deeper and more pathogenic bacteria to the skin surface potentially contaminating the deeper tissues when the incision is made. A study in horses comparing mechanical and nonmechanical sterile preoperative skin preparation with chlorhexidine gluconate showed there was no difference between a five‐minute mechanical scrub and a five‐minute application with no scrubbing (Davids et al. 2015). The manufacturer's instructions for using chlorhexidine direct that it be applied to the site and allowed to remain for two minutes before wiping it off. Wiping it off with either saline or alcohol may remove the chlorhexidine negating its residual activity and should, therefore, not be done. A need for alternating between a preparation solution and saline or alcohol has never been established in any species. A newer skin preparation product, ChloraPrep™ One Step (BD Medical, www.bd.com) is applied to the skin for 30 seconds and left to dry for 30 seconds after which the skin is ready for incision. The World Health Organization Global Guidelines for Prevention of Surgical Site Infections states “The panel recommends alcohol‐based antiseptic solutions based on chlorhexidine gluconate for surgical skin preparation in patients undergoing surgical procedures” (www.who.int/gpsc/ssi‐guidelines/en/).

      Patient Draping

Proper aseptic technique is indicated for all surgical patients regardless of size and species. Place quarter drapes around the surgical site and then cover with a patient drape with a fenestration around the site. Currently, disposable paper drapes are commonly used for both quarter drapes and patient drapes. Avoid the tendency to make a small sterile field as it is then easy to contaminate yourself by accidentally touching objects on the table outside the sterile field. Create a sterile field of the entire table top and take appropriate action to reestablish a sterile field if contamination occurs (Figure 1.2). When working with very small patients, it may be beneficial to use a clear plastic drape over the patient to allow respiration to be monitored; however, other respiratory monitoring devices such as end‐tidal CO₂ monitors allow monitoring of respiration more accurately and do not require the ability to visualize the patient.

Figure 1.2 This 1.2 kg patient is being draped for a thoracotomy. First quarter drapes of Huck towels are placed to isolate the surgical field (a). Then the patient is covered with a patient drape large enough to create a sterile field of the entire table (b). The instruments are on the back table, and this is pulled up to the patient drape to complete the sterile field (c).

      Thermal Support

      Hypothermia during anesthesia is a major concern for many reasons including decreased metabolic functions and excretion of anesthetic agents. Many small exotic animals have a large body surface area/volume ratio predisposing them to developing hypothermia during anesthesia. The body temperature of a rat can drop 18 °F (10 °C) after 20 minutes of anesthesia (Harkness et al. 2010). Use an esophageal or rectal temperature probe to continuously monitor the patient's body temperature. The normal temperature for a given species may not be known; however, once the patient is anesthetized insert a temperature probe to determine its body temperature. Then monitor the temperature and how much it drops during anesthesia. Even in poikilotherms, this is very helpful and can help make decisions about the need to provide additional thermal support.

A short anesthesia and operative time accomplished by having all the necessary equipment ready and accessible will help to minimize hypothermia.