Abstract

Knowledge of baseline health values of threatened or endangered species is key to management and recovery. This information is critically important in the threatened southern sea otter (Enydra lutris nereis) population where a 5-yr decline may be due to infectious disease. Addition of blood collection to field studies of southern and northern (Enhydra lutris kenyoni) sea otters and development of species-specific tests enabled us to determine complete blood count and serum chemistry reference ranges and to test for exposure to a panel of marine and terrestrial pathogens.

Complete blood counts (as available), serum chemistry analysis of 17 analytes, and serologic screening for exposure to five pathogens were performed on samples collected on free-ranging southern (n = 78) and northern (n = 72) sea otters, and from available banked samples from stranded southern sea otters collected for rehabilitation (n = 50). Most blood and serum chemistry values fell within published normal ranges. For free-ranging adult southern and northern sea otters, significant differences were found for gender (sodium and cholesterol) and location (calcium, phosphorus, total bilirubin, and blood urea nitrogen, creatinine, and glucose). For free-ranging southern sea otters, significant differences were found for age (globulins, alkaline phosphatase, alanine transferase, cholesterol, creatinine, blood urea nitrogen, red blood cell count, hemoglobin, hematocrit, and lymphocytes). Free-ranging versus rehabilitated southern sea otter pups exhibited differences for albumin, glucose, red blood cell, hemoglobin, hematocrit, and for neutrophil, lymphocyte, and eosinophil counts. Serologic prevalence of calicivirus, Brucella sp., and Leptospira sp. varied by location. The naivete of these populations to some pathogens such as morbillivirus has important implications for susceptibility to disease outbreaks. Detected exposure to pathogens previously unidentified in southern sea otters will contribute to future veterinary health assessment and management decisions. These baseline health values and seroprevalence results are of significant interest to both wildlife veterinarians and managers and are of critical importance in the development of long-term conservation plans for the southern sea otter.