Hyperglycemia in pinnipeds has been reported to be associated with stress, fasting, diving, and lactation.4-7,12 The reported prevalence of pancreatic disease in pinnipeds is extremely low and usually associated with neoplasia or parasitism.1,2,8-11,13
This is the first report of the employment and effects of insulin therapy in a California sea lion (Zalophus californianus) and the challenges associated with long-term monitoring of a pinniped with diabetes mellitus.
The patient, a 21-year-old neutered male, has been housed at Mystic Aquarium and Institute for Exploration since 2001. In 2004, the patient began displaying chronic elevations of serum triglyceride, cholesterol, and glucose concentrations and severe glucosuria. Several associated clinical signs developed warranting medical intervention: chronic polyuria, polydipsia, and polyphagia; accelerated development of previously noted cataracts; and frequent gastrointestinal episodes including anorexia, abdominal discomfort, diarrhea and vomiting.
Multiple diagnostic aids including abdominal ultrasound, serial hematology and blood chemistry analyses, fecal examination, urinalysis and urine culture, measurement of fructosamine and insulin levels, and evaluation of thyroid and adrenal function have been employed minimizing or eliminating the possibilities of parasitic, endocrine, hepatic, or neoplastic etiologies. The transient nature of the gastrointestinal episodes and associated blood abnormalities, combined with persistent hyperglycemia, were strongly suggestive of chronic pancreatitis with secondary diabetes mellitus.
The patient is maintained on once daily glargine insulin therapy, gastrointestinal protectants and a strict high protein, low-fat diet.3,14 Daily monitoring of glucose regulation utilizes behaviorally-trained blood and urine sampling. Glucose regulation ranges from fair to good and clinical signs of diabetes mellitus have improved.
The authors thank Drs. Mark Saunders and Lynn Walker for their collaboration and ultrasound expertise. The authors also thank Dr. Barbara Byrne and the Microbiology department at U.C. Davis School of Veterinary Medicine for their diagnostic testing support. A special thanks to the Mystic Aquarium California sea lion trainers and staff for all their efforts and training accomplishments, greatly easing the daily monitoring necessary for treating this animal.
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