Abstract

As part of routine physical examinations blood was collected from four pinniped species (harbor seals, Steller sea lions, northern fur seals, and gray seals) maintained at Mystic Marinelife Aquarium. Serum chemistry results were compiled for healthy members of each species and statistical analysis of these data was used to provide normal clinical chemistry values for both individual animals and for each species. Preliminary investigation of differences between species for specific serum chemistry parameters was also conducted. Electrolyte values were found to be constant both within and across species. Enzyme values were found to vary considerably both within and across species.

Introduction

At Mystic Marine life Aquarium (MMA) the husbandry program for pinnipeds in the collection requires blood sampling performed every six to twelve months as an adjunct to routine physical examinations. Data from these examinations are collected and results maintained in the animals' medical records. Hematologic and serum chemistry data yield useful information regarding an animal's general health and/or disease state.

Some of the pinniped serum chemistry data available in the literature are values from wild animals, many of which are heavily parasitized or possibly debilitated. Other data may be compilations of values from samples analyzed using a variety of different analytical procedures. Reliance on these sources often results in a wide variation in "normal" values, and reference to these sources could complicate diagnostic assessments. Reference to compilations of clinical chemistry values for healthy animals held at marine life parks and aquariums can give a more accurate reflection of the true health status for similar animals held elsewhere provided that similar analytical techniques were utilized in the serum chemistry determinations.

Materials & Methods

All blood chemistry profiles for marine mammals held at MMA are run at Pfizer's Medical Research Laboratory, thus providing continuity in analytical determination methods. Routine collection of clinical chemistry data on animals in the collection may also be of benefit in detecting trends in the serum chemistry of an animal as it ages.

Four species of pinnipeds are maintained at Mystic Marine life Aquarium. These species included a colony of eleven harbor seals, Phoca vitulina, a colony of seven steller sea lions, Eumetopias jubata, a colony of three gray seals, Halichoerus grypus, and a colony of sixteen northern fur seals, Callorhinus ursinus. The blood chemistry values of each healthy animal over the period of time it has been held at the aquarium were compiled on an IBM computer and the data analyzed with SAS statistical analysis software. Normal clinical chemistry values for each animal were determined via this method. Twenty-three different parameters are measured on the routine clinical chemistry panel. These include Na, K, Ca, glucose, BUN, creatinine, total bilirubin, ALP, AST, ALT, chloride, total protein, albumin, globulin, A/G ratio, GGTP, SDH, cholesterol, triglycerides, CK, P, LDH, and amylase. Quantile plots were made to assess the normals of the data. All values for each species were also evaluated to determine the normal range of clinical chemistry values for the colony. The clinical chemistry values were not segregated by sex for the colony. A preliminary investigation of age correlation and its effects on clinical chemistry for the species was also conducted.

Results & Discussion

The mean and the ranges of the clinical chemistry values for each of the four species of pinniped are listed in Table 1 along with their coefficient of variance (CV), mean age (in years) and range of ages. The electrolytes (Na, K, Cl, P, Ca) of all the animals in the collection remained very constant and had small CVs, thus small changes in electrolyte levels could be significant and indicative of changes in an animal's health status. Amylase was found to vary greatly across species, with steller seal lions having low activity in contrast to high activity in harbor seals. The steller sea lion's amylase ranged from 0 to 27 IU and the harbor seals ranged 521 to 1103 IU. Whether the disparity in amylase values relates to significant phylogenetic differences or to the sensitivity of the analytical technique has not as yet been investigated The liver enzymes ALP, AST, and ALT all had large CVs. High CV's indicate that a larger change would be necessary to indicate possible liver disease.

An initial investigation to determine which clinical chemistry values had correlations with increases in age was also begun. Because of the small sample size of gray Seals (3), we did not perform age correlations in that colony. Phosphorus was found to be the only value that had a strong age correlation for the remaining three species. varying inversely with age in harbor seals, northern fur seals, and steller sea lions. The steller sea lion also showed other trends detectable with increasing age. These were a decreased calcium level, BUN, total bilirubin, ALP, ALT, albumin, and an increased globulin level. Harbor seals showed minor changes with increased age including an increased BUN, creatinine, and total protein, and a decreased potassium, AST, ALT, SDH, triglycerides, and LDH.

Table 1. Clinical Chemistry means, ranges and coefficient of variance for colonies of four species