UROLITH PREVALENCE AND RISK FACTORS IN ASIAN SMALL-CLAWED OTTERS ( AONYX CINEREUS)

Intestinal T-cell lymphoma in an Asian small-clawed otter: case report and literature review of lymphoma in the subfamily Lutrinae

The Asian small-clawed otter (Aonyx cinereus) is an endangered species that is common in zoologic collections. A 17-y-old female Asian small-clawed otter under human care, with a clinical history of chronic renal disease, was euthanized because of deteriorating health. Histologically, the jejunal wall was infiltrated by a monomorphic population of small neoplastic lymphocytes that expanded the lamina propria of the villi and crypts, and on rare occasions invaded the submucosa. The tumor was composed of T cells (CD3+) with a proliferation index of 16%. Based on the World Health Organization (WHO) Classification of Hematopoietic Neoplasms in Domestic Animals, this lymphoma was classified as an enteropathy-associated T-cell lymphoma (EATL) type 2. We also present here a review of the literature on intestinal lymphoma in the subfamily Lutrinae (otters).

NO PROGRESSION OF UROLITHS IN ASIAN SMALL-CLAWED OTTERS (AONYX CINEREUS) FED A NATURALISTIC CRUSTACEAN-BASED DIET FOR 2 YEARS

Asian small-clawed otters (ASCO; Aonyx cinereus) are a popular species of otter housed in zoological institutions. A common health challenge in this species is the development of uroliths, which may have a dietary origin. Feeding recommendations for ASCO are largely based on the nutrient requirements of domestic carnivore models. Using otter-specific feeding ecology may allow for further refinement of these nutrient recommendations. This study aimed to assess if a naturalistic diet of crustaceans, mollusks, and fish could control the development of uroliths in ASCO. Baseline data were collected on 10 ASCO (five males and five females) of different ages and repeated 2 years after the treatment diet was introduced. Blood and urine parameters, as well as the size of nephroliths based on radiographic images, were recorded. The treatment diet was higher in protein and lower in calcium than the nontreatment diet and did not contain any kibble. During the 2-year treatment trial, blood globulin, glucose, and sodium increased and albumin decreased. Glucosuria and leukocyturia significantly decreased. There were no significant changes in urolith size over the 2 years, and animals without nephroliths at the beginning of the study remained urolith free. The development of nephroliths was significantly reduced during the treatment compared with the year prior. Although interpretation is limited by the methods used, a naturalist diet may have a beneficial impact in the development of uroliths in ASCO.

Animal models of naturally occurring stone disease

The prevalence of urolithiasis in humans is increasing worldwide; however, non-surgical treatment and prevention options remain limited despite decades of investigation. Most existing laboratory animal models for urolithiasis rely on highly artificial methods of stone induction and, as a result, might not be fully applicable to the study of natural stone initiation and growth. Animal models that naturally and spontaneously form uroliths are an underused resource in the study of human stone disease and offer many potential opportunities for improving insight into stone pathogenesis. These models include domestic dogs and cats, as well as a variety of other captive and wild species, such as otters, dolphins and ferrets, that form calcium oxalate, struvite, uric acid, cystine and other stone types. Improved collaboration between urologists, basic scientists and veterinarians is warranted to further our understanding of how stones form and to consider possible new preventive and therapeutic treatment options.