Karen L. Rosenthal, DVM, MS, Diplomate ABVP-Avian
Gastrointestinal disease frequently occurs in pet ferrets. Different etiologies have similar signs so it is dependent upon history, signalment, and ancillary diagnostics to discern the correct cause of disease. This discussion will focus on how to develop a differential diagnosis of gastrointestinal disease in pet ferrets. When investigating gastrointestinal disease in ferrets, use many of the same techniques that are available for dog and cat gastrointestinal disease diagnosis.
Gastrointestinal obstruction is more common in young ferrets. It is easiest to divide ferrets into those under and those over a year of age when determining the etiology of the obstruction. Foreign body obstruction is a common problem in young ferrets. The most common objects are sponges and rubber pieces, such as the inside of sneakers. Gastrointestinal obstruction is more common in ferrets that are allowed out of their cages unsupervised. In older ferrets, trichobezoars are a more common cause of gastrointestinal obstruction. The likely signs of a gastrointestinal obstruction in any age ferret include anorexia and lethargy. Weight loss can be profound if the obstruction is chronic. Other less commonly seen signs include diarrhea, ptyalism and pawing at the mouth. Importantly, vomiting and regurgitation are seen infrequently, no matter where the obstruction occurs in the gastrointestinal tract. On physical examination there is likely evidence of recent weight loss. Discomfort on abdominal palpation and palpation of the foreign object in the gastrointestinal tract is common. It may be difficult to palpate objects in the stomach as the stomach normally lies inside the ribcage. Abdominal radiographs reveal a fluid or gas filled stomach and/or a gas pattern in the intestinal tract. Occasionally a radio-opaque object is apparent in the tract on radiographs. In most cases, the diagnosis is unequivocal and a barium series is not usually necessary. Surgery, enterotomy or gastrotomy, is the preferred treatment. Complications such as peritonitis are rare. If surgery is not possible, attempt treatment with feline hairball laxatives. There is limited success with this method and sometimes valuable time is lost while treating with medical preparations.
Gastro and duodenal ulcers occur in both young and older ferrets. Gastrointestinal ulcers in pet ferrets are more likely to be secondary to another disease and infrequently appear to be a primary problem. A variety of signs are observed including anorexia, lethargy, teeth grinding, ptyalism, diarrhea, and melena. Physical examination is usually non-remarkable with weight loss and a diarrhea-stained perineum potentially present. Other findings can include ulcerations along the hard palate and pain on abdominal palpation. Hematology may reveal a mild, regenerative anemia. It is likely that a bacterial agent, Helicobacter mustelae, is responsible for the ulcers. A positive diagnosis of this organism is often difficult as not all laboratories are equipped to culture this bacteria and special stains are needed to identify it in tissues. Fecal tests for helicobacter may be useful in some situations but since it is assumed most ferrets are infected with helicobacter, it is difficult to interpret a positive fecal result. Signs, tissue biopsies, cultures, and response to treatment all help to confirm a diagnosis of helicobacter infection. Treatment depends on the severity of illness. Amoxicillin at 20 mg/kg q8-12hrs PO along with metronidazole at 20 mg/kg q12hrs PO can be administered. Alternative treatment protocols include Biaxin (clarithromycin) at 12.5 mg/kg q8hrs PO and Zantac (ranitidine) 24 mg/kg q8hrs PO. Two other medications to consider include chloramphenicol 50 mg/kg q8-12hrs PO and pepsid 0.5 mg/kg q24hrs PO. Other medications include Pepto-Bismol at 0.25 ml/kg q6hrs PO and cimetidine at 10 mg/kg q8hrs IV or PO. Supportive care such as fluids, iron, and nutritional support may also be necessary. In most cases, the likelihood of a primary disease should be investigated.
Eosinophilic gastroenteritis (EGE) is infrequently seen. It is characterized by chronic weight loss, anorexia, and diarrhea. Palpation may reveal thickened intestinal loops and enlarged mesenteric lymph nodes. The etiology is unknown although one proposed cause includes food allergies. Diagnose EGE by observing peripheral eosinophilia on the complete blood count and a biopsy showing eosinophilic infiltration of the stomach and small intestine. Treatment is not well defined as etiology is unknown but suggestions include ivermectin at 0.4 mg/kg SC and prednisone at 1.25 to 2.5 mg/kg PO with a tapering dose. Another approach is to treat this as a food allergy and to radically alter the diet. This could include a diet of prey items rather than commercially manufactured food.
Internal parasites are uncommon in ferrets since most pet ferrets live indoors. The list of possible parasites includes: Toxoscaris leonia, Toxocara cati, Ancylostoma sp., Dipylidium caninum, and Giardia spp. Coccidia is the most common internal parasite seen in ferrets. Coccidia primarily affect young ferrets and is more likely observed after a stressful event. Coccidia can cause severe diarrhea, dehydration, and metabolic imbalance. Rectal prolapse is not uncommon in young ferrets with coccidia. Diagnose coccidia by direct fecal examination. Treatment for coccidia is accomplished with sulfa drugs such as sulfadimethozine at 50 mg/kg once PO and then 25 mg/kg q24hrs for nine days.
Megaesophagus is an uncommon disease. It is usually seen in middle-aged ferrets. Signs include regurgitation with weight loss. Diagnose megaesophagus based on clinical signs and diagnostic imaging. Radiographs reveal a prominent esophagus and fluoroscopy shows an enlarged, flaccid esophagus. The etiology is unknown in most cases. Treatment includes supportive care but this is a terminal, progressive disease. Ferrets usually die from aspiration pneumonia.
Proliferative bowel disease appears to be a rare disease in pet ferrets and is mostly apparent in younger animals. It can begin as an acute disease associated with stress. The first signs include acute colitis, tenesmus, and green diarrhea flecked with blood. It then progresses as a nonspecific gastrointestinal disease. In the chronic form, it is seen as chronic diarrhea, hematochezia, anorexia, weight loss, and even rectal prolapse. Severe cases develop neurologic diseases such as ataxia, head tilt, and tremors. The proposed etiology is the organism Lawsonia intracellularis. The diagnosis is based on clinical signs, tissue biopsies from the colon, and response to treatment. Biopsies reveal mucosal thickening and glandular epithelium hyperplasia. Treatment includes chloramphenicol at 50 mg/kg q12hrs for 2-3 weeks. Supportive care is necessary if the ferret is debilitated. Rarely, ferrets may die despite supportive care.
In the last 5-6 years, a new gastrointestinal disease has been seen in ferrets from the United States termed, "green diarrhea disease" or epizootic catarrhal enteritis (ECE). A proposed etiology is a corona virus. This disease appears to be highly infective, spreads rapidly amongst a group of ferrets, and people act as fomites. Even after apparent recovery, the disease can recur. Older ferrets appear to develop a more severe form of this disease than do younger ferrets. Younger ferrets usually do not even show signs of illness and appear to be asymptomatic carriers. A variety of signs are seen with this disease including anorexia, lethargy, diarrhea, and melena. Hematology may reveal an elevated WBC count, slight anemia, and biochemistry results usually show a highly elevated ALT and, as the disease progresses, an elevated SAP. Treat with supportive care including antibiotics, fluids, and nutrition. If possible, isolate the effected ferret.