Nonabdominal surgeries in ferrets (Proceedings)
General surgical considerations
In general, ferrets are hardy and make excellent surgical candidates. A complete physical examination and appropriate pre-operative laboratory tests are essential parts of successful surgery. Since ferrets are commonly diagnosed with cardiac disease care should be taken to closely examine the heart and lungs. Some of the clinical signs of cardiac disease such as weight loss, anorexia, inactivity, weakness, and hind limb ataxia are common to other diseases for which surgery may be contemplated. Ferrets often do not cough with cardiac disease and may be asymptomatic. Chest radiographs, an electrocardiogram, and an echocardiogram should be performed prior to surgery if cardiac disease is suspected.
A complete blood count and biochemistry profile should be performed prior to major surgery or in ferrets over two years of age. Any abnormalities should be addressed prior to surgery. The gastrointestinal transit time in ferrets is only three to four hours. They only need to be fasted for approximately three hours prior to anesthesia. A longer fast can induce hypoglycemia even in healthy ferrets and should be avoided. Because of their small size, body temperature should be closely monitored during surgery and recovery. Precautions to prevent heat loss include a circulating warm water blanket, warmed saline for irrigation, administration of warmed intravenous fluids, a radiant heat lamp and a force warm air blanket.An intravenous or intraosseous catheter should be placed and warmed fluids administered during most procedures at a rate of 10 ml/kg/hr. Also, due to the fact that ferrets can have insulinomas which may or may not be clinically evident, an intravenous fluid solution containing 5% dextrose such as lactated Ringer's solution with added dextrose is often recommended. Ferret skin is relatively thick, so when placing a catheter it is often helpful to make a small nick in the skin with a # 11 scalpel blade or the bevel of a 20 ga needle before attempting to pass the catheter through the skin. A 24 gauge cephalic catheter works well in most ferrets.
A common finding during abdominal surgery is an enlarged spleen. For this reason it is important to avoid damage to the spleen when entering the abdomen as it may cross the ventral midline. Ferrets lack a cecum and the small and large intestines are difficult to distinguish anatomically. The transition from small intestine to colon is grossly marked by only by a change in the pattern of the blood supply.
Post surgical bruising along the incision is not uncommon in ferrets. This is seen even with diligent attention to hemostasis. Gentle tissue handling may help avoid dermal bruising and thumb forceps should be used for counter pressure, not for pinching the skin edges. The discoloration usually resolves within 5 to 7 days, but owners should be warned about the possibility of it developing.
Once the patient is awake encourage it to eat. If it does not eat right away, continue IV fluids with dextrose at a maintenance rate until the patient begins to eat. Even with GI surgery, studies have shown that enterocytes need nutrition to heal mucosal incisions. Withholding food after surgery is not indicated and may delay healing.
As in cats, rebound hyperthermia during recovery from anesthesia occurs in ferrets, so the recovery cage should not be prewarmed and care should be taken to avoid overheating. The body temperature should be closely monitored (q 30-60 min.) until it is about 100° F. Heating devices are removed but body temperature should be closely monitored. There are no reports of clinical problems from this rebound hyperthermia. If the temperature exceeds 104°F consider an IV NSAID or external cooling systems such as cold packs.
Many of the same instruments used in canine and feline surgery can be used in ferrets. The Stay Retractor is very useful for retracting the abdominal wall for celiotomy or for retracting the wound edges for other procedures (Lonestar Medical Products Inc). Small needle holders and mosquito forceps are very useful in ferret surgery and microsurgical instruments are ideal. In addition, the small and medium size hemostatic clips (e.g. Hemoclips; Weck Surgical Instruments; RICA Surgical, or Ligaclips; Ethicon) make occlusion of vessels much easier in tight, hard-to-reach places. A generous supply of sterile cotton tipped applicators is very useful for blotting and to aid in tissue dissection.