Abstract

Diseases of the intestinal system of most species are usually the most difficult to understand, diagnose, and properly treat. This is also true in cetacean species where gastroscopy is often limited to the first of multiple chambers, where fecal material is already liquid and where sampling is complicated by acquisition and difficulties in handling. Clinical disease of the small and large bowel is poorly understood. The small numbers of cetaceans maintained in controlled environments affects the progress, understanding, and classification of small and large bowel disease conditions.

Antibiotic use has resulted in better survival rates in cetaceans, but it is often empirical and is affected by experience, comfort, and prejudice. As we incorporate more antibiotics into general use and see more clinical manifestations of intestinal disease, we will all benefit from developing diagnostic protocols which will help to facilitate our understanding of these processes.

Human classifications of bowel diseases include inflammatory bowel disease (Crohn’s disease, ulcerative colitis, lymphocytic colitis, collagenous colitis), irritable bowel disease (etiology unknown), and infectious bowel disease (traveler’s diarrhea—bacterial, viral, parasitic). Another common bacterial infection, Clostridium difficile, is often linked to antibiotic use and their secondary effects on the intestinal flora.

Cetaceans that are showing signs of intestinal illness will often lose their appetite as well as show possible signs of depression, lethargy, isolation, and decreased cooperation. The first diagnostic tests done are usually a complete blood count and serum chemistries. Bloodwork findings may include an elevated white count, decreased red cell indices, elevated fibrinogen, elevated sedimentation rate, and a decreased serum iron. Often on the basis of an increased white count antibiotics are begun. If all returns to normal the diagnostic workup usually stops so there is little data regarding the initial involvement of intestinal disease. If the abnormalities persist then additional procedures are pursued.

Typical, diagnostic techniques for bowel disease in cetaceans should include aerobic and anaerobic cultures, cytology of fecal material, and direct parasite exam. To aid in bacterial flora, interpretation it is recommended that fecal cultures be done on animals while they are clinically normal. Anaerobic cultures are useful in determining the presence of possible pathogens and in correlating this with cytology results. A research project done at SeaWorld on clostridial organisms showed that the vast majority of isolates were Clostridium perfringens type A and that about 70% were toxin producers.

The diagnosis of diarrhea is related to the frequency of defecation rather than the consistency of the stool observed. Feces for cytology are collected with a flexible open-ended tube with sterile technique. Cytology results in colitis cases may vary in findings and severity. Inflammatory cells may be classified based on morphology and numbers. The bacterial flora is evaluated for composition and morphology. Special note is taken when there is a predominance of one morphologic type such as bacilli with the presence of spores that may indicate clostridial involvement.

One technique that has not been adequately utilized is colonoscopy. It is often assumed that the size of the rectum and the liquid fecal material will make this a low yield procedure. This deserves further evaluation for possible inclusion as a more common technique, although, typical scope diameters may be a limiting factor for some clinicians. With an increased number of interested clinicians we may then approach a classification system similar to the human field.