Comparison of Serum Thyroid Hormone Levels in Green-winged Macaws (Ara chloropterus) Using Radio and Chemiluminescent Immunoassays.

This study compared the use of radioimmunoassay (RIA) and chemiluminescent immunoassay (CLIA) to measure serum thyroid hormone levels in green-winged macaws (Ara chloropterus). The sample group comprised 20 male and 13 female (n = 33) healthy, captive green-winged macaws of reproductive age but outside of breeding season. Mean free triiodothyronine (T3), total T3, and free thyroxine (T4) measured by CLIA and RIA corresponded to 5.11 and 5.08 pmol/L (3.33 and 3.31 pg/mL), 1.59 and 1.56 nmol/L (103.5 and 101.5 ng/dL), and 8.25 and 8.82 pmol/L (0.64 and 0.69 ng/dL), respectively. Mean total T4 by RIA corresponded to 6.29 nmol/L (0.49 µg/dL). Mean free T4 and thyroid-stimulating hormone (TSH) levels differed according to immunoassay method, with higher values measured by RIA compared with CLIA. Sex influence was statistically significant in immunoassay results only on free T3 levels. Free T3 levels measured by RIA were higher than levels measured by CLIA in male birds, but this difference was not found with the female bird samples. Conversely, free T3 levels measured by CLIA were higher in the female macaws compared with male birds. Comparative analysis of thyroid hormone measurements in this study revealed that RIA and CLIA are equivalent methods to measure free T4 and total T3 levels but not TSH levels. These findings support the use of CLIA for free T4 and total T3 level determinations in green-winged macaws. However, the CLIA kit used in this study provided invalid total T4 level results for the macaws sampled. Radioimmunoassay and CLIA were equally ineffective for determining TSH levels in this species.

CLINICAL OBSERVATIONS OF BEE ENVENOMATION IN TOUCANS.

There are numerous reports on envenomation, even fatal, secondary to bee attacks in humans and other mammals. In birds, reports on those incidents are scarce and there are none regarding honeybee (Apis mellifera) stings in toucans. In the first case presented, an adult female red-breasted toucan (Ramphastos dicolorus) received at least five bee stings in the periophthalmic area. Within 5 h the bird was lethargic and dehydrated. The urates were yellowish. Three days later the bird showed a moderate anemia, but no changes in the leukocyte count, beyond an elevated heterophil: lymphocyte ratio. Blood chemistry showed hyperglycemia, hypoalbuminemia and elevated aspartate aminotransferase and creatine kinase. Alterations in electrolyte values were also noted. Fourteen days later bile acid elevation was observed. Hematocrit levels normalized after 2 wk. A second incident involved a breeding pair of toco toucans (Ramphastos toco). While the female toco toucan received 10 stings and showed mild clinical manifestations, the male toco toucan was more severely attacked, receiving 40 stings, and died overnight. Despite the relative gravity of the attack (in terms of number of stingers in relation to body weight) both surviving birds recovered in less than 2 wk. To the authors' knowledge, fatal bee envenomation in birds has been reported only in pigeons and macaws. The findings described in this report suggest that toucans are less sensitive to bee venom when compared with pigeons and may have higher tolerance to bee venom compared with mammals. Honeybee envenomation must be considered a potential threat when considering toucan husbandry in zoos and collections.

SUCCESSFUL REDUCTION OF FEATHER-DAMAGING BEHAVIOR BY SOCIAL RESTRUCTURING IN A GROUP OF GOLDEN CONURES (GUARUBA GUAROUBA).

A variety of infectious and noninfectious causes may contribute to feather-damaging behavior (FDB) in birds. This paper describes an episode of FDB behavior related to an isosexual group composition in a group of 20 golden conures (Guaruba guarouba) kept in a collective aviary. After ruling out infectious causative agents and analyzing the social bird group composition over a period of 10 yr, the male to female ratio of the group was reduced from 1.7 to 1.0. This intervention resulted in a significant improvement of the feather condition and improved reproduction. Further analysis revealed that FDB was not correlated to age, gender, or origin. In addition, FDB was associated with stress, as reflected by an elevated heterophil : lymphocyte ratio that decreased significantly following social restructuring. This study stresses the importance of an appropriate male to female ratio when golden conures are kept in aviaries.

PRESUMPTIVE PIT VIPER ENVENOMATION IN PSITTACINES IN A BRAZILIAN ZOO.

Snake bites represent a serious public health risk in many regions of the globe, especially in tropical areas. Clinical signs and postmortem changes are well described in human and other mammalian species. However, detailed case reports about venomous snake attacks in avian species are limited. This report describes presumptive fatal envenomations in three psittacines caused by pit vipers in a Brazilian zoo. In one case, a Brazilian lancehead (Bothrops moojeni) was captured in the aviary. In all three cases the dermis around the suspected snake bite area exhibited hemorrhages and edema. Histologically, degeneration and necrosis of subcutaneous musculature were observed. Lung, heart, and kidneys displayed focal hemorrhages. The local changes are similar to those described for mammalian patients including humans. However, except for the parenchymatous hemorrhages, additional external and internal gross and histopathological lesions were missing. After ruling out other causes, such as aggression and dicoumarinic intoxication, the presumptive diagnosis of snake envenomation was made. The smaller size and variabilities of pathophysiological effects of the venom in parrots might explain the different lesion patterns observed, compared with mammals. Possibly, the birds may have reacted differently to envenomation by pit vipers and died before the venom could cause macroscopic and histological changes often observed in mammals.