Effect of age, sex, and season on the variation in blood analytes of a clinically normal ex situ population of killer whales (Orcinus orca).

BACKGROUND: The effects of sex, age, and season on blood analyte concentrations have not been investigated for the killer whale (Orcinus orca). Defining these changes provides background data for improving the care of managed populations and defines normal changes that could occur in wild counterparts. OBJECTIVES: We aimed to define hematologic and serum biochemical variation by age, sex, and season for an ex situ killer whale population. METHODS: Blood samples collected from killer whales during normal wellness exams were retrospectively identified. Killer whales were categorized by age; calf (0-2.9 years), juvenile (3-10.9 years), early adult (11-20.9 years), adult (21-30.9 years), and aged (>30.9 years); sex; and season. Standard CBC and biochemistry were collated, and only samples without evidence of disease were used. A mixed effects maximum likelihood regression with animal identification (ID) as the random effects variable was used to compare groups with a significance set at P ≤ 0.01. RESULTS: All analytes differed by age, while only four differed by sex. Red blood cell parameters and associated renal analytes increased with age, while liver-associated analytes and glucose decreased. Season affected 59% of the blood analytes. CONCLUSIONS: Aged killer whales showed strong evidence of altered physiology as compared with younger animals. Anemia did not develop with age as was observed in one bottlenose dolphin population. Observed decreases in renal function could be caused by chronic disease or dehydration. Decreases in immune function parameters suggest immune senescence. These results provide background data for evaluating the health of managed and free-ranging killer whales.

Longitudinal evaluation of leukocyte transcripts in killer whales (Orcinus Orca).

Early identification of illness and/or presence of environmental and/or social stressors in free-ranging and domestic cetaceans is a priority for marine mammal health care professionals. Incorporation of leukocyte gene transcript analysis into the diagnostic tool kit has the potential to augment classical diagnostics based upon ease of sample storage and shipment, inducible nature and well-defined roles of transcription and associated downstream actions. Development of biomarkers that could serve to identify "insults" and potentially differentiate disease etiology would be of great diagnostic value. To this end, a modest number of peripheral blood leukocyte gene transcripts were selected for application to a domestic killer whale population with a focus on broad representation of inducible immunologically relevant genes. Normalized leukocyte transcript values, longitudinally acquired from 232 blood samples derived from 26 clinically healthy whales, were not visibly influenced temporally nor by sex or the specific Park in which they resided. Stability in leukocyte transcript number during periods of health enhances their potential use in diagnostics through identification of outliers. Transcript levels of two cytokine genes, IL-4 and IL-17, were highly variable within the group as compared to the other transcripts. IL-4 transcripts were typically absent. Analysis of transcript levels on the other genes of interest, on an individual animal basis, identified more outliers than were visible when analyzed in the context of the entire population. The majority of outliers (9 samples) were low, though elevated transcripts were identified for IL-17 from 2 animals and one each for Cox-2 and IL-10. The low number of outliers was not unexpected as sample selection was intentionally directed towards animals that were clinically healthy at the time of collection. Outliers may reflect animals experiencing subclinical disease that is transient and self-limiting. The immunologic knowledge derived from longitudinal immunologic studies in killer whales, as was the target of the present study, has the potential to improve diagnostics and health related decision making for this and other domestic and free-ranging cetacean species.

Serologic response of harbor seals (Phoca vitulina) to vaccination with a recombinant canine distemper vaccine.

Morbilliviruses pose a significant threat to marine mammal populations around the world and have been associated with multiple epizootics in pinnipeds and cetaceans. As part of a preventive veterinary medical program, five harbor seals (Phoca vitulina) in a managed collection were vaccinated with a recombinant canarypox-vectored canine distemper virus vaccine. The vaccine was evaluated for safety (by monitoring seals for local and systemic adverse effects and by testing for shedding of the canarypox vector) and efficacy (by testing for serum neutralizing antibodies). None of the seals showed signs of local or systemic adverse reactions to the vaccination. Three seals vaccinated once did not seroconvert, but the recombinant vaccine induced a persistent serum virus neutralizing titer (12 mo) in the two seals that were vaccinated twice, 1 mo apart.

Risk factors associated with cataracts and lens luxations in captive pinnipeds in the United States and the Bahamas.

OBJECTIVE: To determine risk factors for lens luxation and cataracts in captive pinnipeds in the United States and the Bahamas. DESIGN: Cross-sectional study. ANIMALS: 111 pinnipeds (99 California sea lions [Zalophus californianus], 10 harbor seals [Phoca vitulina], and 2 walruses [Odobenus rosmarus]) from 9 facilities. PROCEDURES: Eyes of each pinniped were examined by a veterinary ophthalmologist for the presence of cataracts or lens luxations and photographed. Information detailing husbandry practices, history, and facilities was collected with a questionnaire, and descriptive statistical analyses were performed for continuous and categorical variables. Odds ratios and associated 95% confidence intervals were estimated from the final model. RESULTS: Risk factors for lens luxation, cataracts, or both included age >or= 15 years, history of fighting, history of ocular disease, and insufficient access to shade. CONCLUSIONS AND CLINICAL RELEVANCE: Diseases of the lens commonly affect captive pinnipeds. Access to UV-protective shade, early identification and medical management of ocular diseases, and prevention of fighting can limit the frequency or severity of lens-related disease in this population. An extended life span may result from captivity, but this also allows development of pathological changes associated with aging, including cataracts.

Baseline circulating immunoglobulin G levels in managed collection and free-ranging bottlenose dolphins (Tursiops truncatus).

Serum immunoglobulin levels can be used as markers for immune status. However, tools to evaluate immune function and status of cetaceans under veterinary care have been limited, including the lack of an assay quantifying serum immunoglobulin G. Here, we report on the development of a validated competitive enzyme-labeled immunosorbent assay (cELISA) for the quantification of bottlenose dolphin (Tursiops truncatus) IgG. Using the cELISA, baseline serum IgG levels were established for two managed collections and one free-ranging dolphin population. Serum IgG levels ranged from 3.2 to >11.49 mg/ml. Overall, free-ranging dolphins had higher serum IgG levels than managed collection dolphins. High total white blood cell and eosinophil counts were the best predictors of IgG levels, suggesting higher IgG levels are likely attributable to a higher parasitic load of free-ranging dolphins.

Cross-reactivity between immunoglobulin G antibodies of whales and dolphins correlates with evolutionary distance.

Growing morphological and molecular evidence indicates that the porpoises, dolphins, and whales evolved within the even-toed ungulates, formerly known as Artiodactyla. These animals are now grouped in the Cetartiodactyla. We evaluated the antigenic similarity of the immunoglobulin G (IgG) molecules of 15 cetacean species and the domestic cow. The similarity was scored using three distinct antibodies raised against bottlenose dolphin (Tursiops truncatus) IgG in a Western blot, an indirect enzyme-linked immunosorbent assay (ELISA), and a competitive ELISA format. A score was generated for the genetic distance between each species and T. truncatus using the cytochrome b sequence. Each antibody displayed a distinct pattern of reactivity with the IgG antibodies of the various species. The monoclonal antibody (MAb) specific for the gamma heavy chain of T. truncatus was reactive with all monodontids, delphinids, and phocoenids. The light-chain-specific MAb reacted with IgG of delphinoid and phocoenid species and one of the two mysticete species tested. The polyclonal antibody was broadly cross-reactive across all cetaceans and the domestic cow. Using the MAb specific for the gamma heavy chain, the degree of IgG cross-reactivity ranged from less than 17% for the mysticetes to 106% for killer whale Orcinus orca. The IgG in beaked whale and baleen whale sera was significantly less cross-reactive with bottlenose dolphin IgG than sera from other toothed whales. A strong negative correlation was demonstrated between antigenic cross-reactivity of IgG molecules and the genetic distance of their hosts. The data generated will be useful for the development of clinical serodiagnostics in diverse cetacean species.