ABSTRACT. To determine how blood values in bottlenose dolphins changed during the year, 504 blood samples were taken from 9 dolphins from 1991 to 1999 and clinical blood examinations were undertaken monthly including 3 hematological and 19 serum chemistry tests. In creatinine, significant seasonal changes were found among three groups of adult males, adult females and juveniles, and the average values in summer were 15-38% higher than those in winter. In two out of three groups the average total cholesterol value were h ighest in winter, and the lowest of all groups were in summer. In two other groups the peaks of average FFA value were recorded in sum mer, and the lows were in winter. KEY WORDS: bottlenose dolphin, seasonal change, serum chemistry.J. Vet. Med. Sci. 64(11): 1075-1078, 2002 The physiology of free-living marine mammals adapts to seasonal environmental changes. It is known that bottlenose dolphins migrate seasonally, and the migration is probably a response to temperature changes [16,21]. Several physiological parameters, for example, the thickness of blubber [25], the body mass [21] and the rectal body temperature [23], are known to have seasonality even in captive dolphins.Seasonal changes in hematology have been recorded in birds [1,5,9,17,20,27] The blood samples taken from wild dolphins may be affected by several factors, including their handling stress and their diet. We previously reported how diet affected the blood composition of this species [24]. Therefore, it is necessary to examine the case of bottlenose dolphins in captivity. The information presented should help to establish a hematological base line of seasonal changes for bottlenose dolphins. It is important to be aware of seasonal changes for evaluating long-term physiological variations, for example, during pregnancy. Therefore, this report examines how blood values change seasonally in captive bottlenose dolphins, Tursiops truncatus, from the results of clinical blood examinations at Enoshima Aquarium from 1991 to 1999.Hematological data were compiled from the routine health records of 9 bottlenose dolphins (Table 1) which were divided into three groups: adult males (two dolphins, aged over 12 years), adult females (two dolphins, aged over 12 years), and juveniles (one male and four females, aged under 6 years) at Enoshima Aquarium, Kanagawa, Japan. This age classification was not changed throughout the study period. Three of these dolphins were born at this facility. The other six dolphins originated in waters around Japan. When they were brought into captivity, we estimated their ages from body length and body mass [22]. Clinical data over a 9-year period (1991 to 1999) for adult males and females, and a 5-year period (1995 to 1999) for juveniles were used, and a total of 504 blood samples were taken. Only blood samples from dolphins judged to be normal by behavior, appearance, or food consumption were used.The tank is outdoors with a total seawater volume of 5000 m 3 (45 m × 25 m, oval-shaped, with a depth of 3.5 to 5.5 m).

Brown adipose tissue (BAT) plays an important role in thermoregulation in species living in cold environments, given heat can be generated from its chemical energy reserves. Here we investigate the existence of BAT in blubber in four species of delphinoid cetacean, the Pacific white-sided and bottlenose dolphins, Lagenorhynchus obliquidens and Tursiops truncates, and Dall’s and harbour porpoises, Phocoenoides dalli and Phocoena phocoena. Histology revealed adipocytes with small unilocular fat droplets and a large eosinophilic cytoplasm intermingled with connective tissue in the innermost layers of blubber. Chemistry revealed a brown adipocyte-specific mitochondrial protein, uncoupling protein 1 (UCP1), within these same adipocytes, but not those distributed elsewhere throughout the blubber. Western blot analysis of extracts from the inner blubber layer confirmed that the immunohistochemical positive reaction was specific to UCP1 and that this adipose tissue was BAT. To better understand the distribution of BAT throughout the entire cetacean body, cadavers were subjected to computed tomography (CT) scanning. Resulting imagery, coupled with histological corroboration of fine tissue structure, revealed adipocytes intermingled with connective tissue in the lowest layer of blubber were distributed within a thin, highly dense layer that extended the length of the body, with the exception of the rostrum, fin and fluke regions. As such, we describe BAT effectively enveloping the cetacean body. Our results suggest that delphinoid blubber could serve a role additional to those frequently attributed to it: simple insulation blanket, energy storage, hydrodynamic streamlining or contributor to positive buoyancy. We believe delphinoid BAT might also function like an electric blanket, enabling animals to frequent waters cooler than blubber as an insulator alone might otherwise allow an animal to withstand, or allow animals to maintain body temperature in cool waters during sustained periods of physical inactivity.

A 4-year and 2-month-old male capybara (Hydrochoerus hydrochaeris) was diagnosed with squamous cell carcinoma on the buttocks after chronic recurrent dermatosis. The capybara was euthanized, examined by computed tomography and necropsied; the tumor was examined histologically. Computed tomography showed a dense soft tissue mass with indistinct borders at the buttocks. Histological examination of the tumor revealed islands of invasive squamous epithelial tumor cells with a severe desmoplastic reaction. Based on the pathological findings, the mass was diagnosed as a squamous cell carcinoma. This is the first study to report squamous cell carcinoma in a capybara.

From an evolutionary perspective, the ancestors of cetaceans first lived in terrestrial environments prior to adapting to aquatic environments. Whereas anatomical and morphological adaptations to aquatic environments have been well studied, few studies have focused on physiological changes. We focused on plasma amino acid concentrations (aminograms) since they show distinct patterns under various physiological conditions. Plasma and urine aminograms were obtained from bottlenose dolphins, pacific white-sided dolphins, Risso's dolphins, false-killer whales and C57BL/6J and ICR mice. Hierarchical cluster analyses were employed to uncover a multitude of amino acid relationships among different species, which can help us understand the complex interrelations comprising metabolic adaptations. The cetacean aminograms formed a cluster that was markedly distinguishable from the mouse cluster, indicating that cetaceans and terrestrial mammals have quite different metabolic machinery for amino acids. Levels of carnosine and 3-methylhistidine, both of which are antioxidants, were substantially higher in cetaceans. Urea was markedly elevated in cetaceans, whereas the level of urea cycle-related amino acids was lower. Because diving mammals must cope with high rates of reactive oxygen species generation due to alterations in apnea/reoxygenation and ischemia-reperfusion processes, high concentrations of antioxidative amino acids are advantageous. Moreover, shifting the set point of urea cycle may be an adaption used for body water conservation in the hyperosmotic sea water environment, because urea functions as a major blood osmolyte. Furthermore, since dolphins are kept in many aquariums for observation, the evaluation of these aminograms may provide useful diagnostic indices for the assessment of cetacean health in artificial environments in the future.

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