Hematologic, plasma biochemistry, and select nutrient values in captive smooth dogfish (Mustelus canis)

The Indianapolis Zoo maintains a large collection of smooth dogfish (Mustelus canis). During the first several years of captivity, there was a period of high mortality in adult, wild-caught sharks in the collection. Smooth dogfish with superficial abrasions would rapidly succumb to infection and death, regardless of the treatment approach. Although the sharks did successfully produce viable offspring, there was an elevated pup mortality rate, with 0% of the pups reaching 1 yr of age during the same period of high mortality in adult sharks. This poor response to captivity prompted interest in the physiologic response of these animals to illness. The objective of this investigation was to establish a preliminary data set of hematologic and plasma chemistry reference intervals, along with select nutrient parameters specific to wild-caught adults maintained in prolonged captivity (i.e., greater than 22 mo). Blood samples were collected from 20 clinically healthy, male (n = 10) and female (n = 10) dogfish sharks at the Oceans facility at the Indianapolis Zoo. Although gender differences in mortality rate were not apparent, complete blood cell counts, plasma biochemical profiles, and select nutrient analyses were performed and analyzed accordingly. Statistically significant differences (P < or = 0.05) specific to sex were determined for parameters including packed cell volume (PCV), absolute and relative fine eosinophilic granulocytes, relative percentage of coarse eosinophilic granulocytes, globulins, the albumin/globulin ratio, total protein, phosphorus, iron, selenium and copper. White blood cell counts appear to be lower in this species compared to other captive elasmobranchs. Further research into appropriate hematology standards including nutritional parameters appears warranted.