NATURALLY OCCURRING SECONDARY NUTRITIONAL HYPERPARATHYROIDISM IN CATTLE EGRETS (BUBULCUS IBIS) FROM CENTRAL TEXAS

Investigating factors of metabolic bone disease in baboons (Papio spp.) using museum collections

OBJECTIVES

To assess manifestations of metabolic bone disease (MBD) and their potential environmental and phenotypic factors in captive and non-captive baboon (Papio spp.) specimens.

MATERIALS AND METHODS

Our sample consisted of 160 baboon specimens at the Smithsonian's National Museum of Natural History accessioned from 1890 to 1971. Combining cranial indicators of MBD and the museum's historical data, we examined factors contributing to likely instances of MBD. We used binomial-family generalized linear models to assess differences in MBD frequency by environment (captive, non-captive), specimen accession year, and skin color (light, medium, dark).

RESULTS

Indicators of MBD were most frequently observed in captive baboons, with a decrease in MBD frequency over time. Fifteen non-captive individuals showed indicators of MBD, which are the first published cases of MBD in non-captive nonhuman primates (NHPs) to our knowledge. The most common MBD indicators were bone porosity (n = 35) and bone thickening/enlargement (n = 35). Fibrous osteodystrophy was observed frequently in our sample, likely relating to nutritional deficiencies. We found no association between exposed facial skin color variation and MBD.

CONCLUSIONS

Our findings are consistent with historical accounts of MBD prevalence in captive facilities, especially earlier in the 20th century. A decrease in MBD prevalence later in the 20th century likely reflects improvements in housing, diet, and veterinary care in captive settings. Causes of MBD development in non-captive baboons should be further explored, as understanding the potential health impacts that anthropogenic environments impose on NHPs is imperative as humans increasingly alter the natural world in the 21st century.

MANIFESTATIONS OF HYPERPARATHYROIDISM IN JUVENILE WHOOPING CRANES (GRUS AMERICANA)

Juvenile whooping cranes (Grus americana) raised for wild release were found to have an increased incidence of rib fractures at fledging in 2017 compared with the previous 16 years. Serum analysis showed 30-day-old juveniles in 2017 (n = 12) had significantly lower 25-hydroxyvitamin D3 and significantly higher parathyroid hormone concentrations than juveniles in 2010 (n = 6) with no history of rib fractures. Increased serum parathyroid hormone concentrations in the 2017 juveniles persisted to fledging age. Review of dietary and environmental management revealed that juveniles in 2017 were provided a commercial diet with a lower, and perhaps suboptimal, calcium:phosphorus ratio and experienced reduced time outdoors in the first month after hatch, presumably resulting in less ultraviolet B radiation exposure. Mild hyperparathyroidism in precocial whooping cranes may result when dietary constraints and/or outdoor access is compromised and manifest as rib fractures in the absence of traumatic injury.

CLINICAL AND PATHOLOGIC FINDINGS OF AN OUTBREAK OF VITAMIN D3-RESPONSIVE METABOLIC BONE DISEASE IN HERON AND EGRET (FAMILY ARDEIDAE) CHICKS FED CAPELIN (MALLOTUS VILLOSUS)

An increase in cases of metabolic bone disease (MBD) in chicks of six species of heron and egret (family Ardeidae) was identified at a wildlife rehabilitation center in the spring and summer of 2018. The outbreak affected 34.3% of birds in care for four or more days during the first 3 mo of the study and was the most common reason for euthanasia during that time. Cases were characterized by lameness, increased flexibility of multiple long bones, angular deformities, and bone fractures. Gross postmortem examinations were conducted on 145 nestlings and fledglings that died or were euthanatized either because of MBD or for unrelated conditions. Histology was performed in four cases and three controls. Histologic findings were characterized by multiple lesions in the appendicular long bones, including variable elongation of the physis, retention of cartilage cores in the metaphyseal primary spongiosa, poorly mineralized osteoid seams within the primary spongiosa, thinning or lack of diaphyseal cortical bone compaction, and folding fractures typically propagating through the physis-metaphyseal interface. Folding fractures were often associated with focal metaphyseal fibroplasia. The parathyroid gland diameter of birds diagnosed postmortem with MBD in care was significantly larger than that of unaffected birds. The authors hypothesized that a dietary deficiency of vitamin D₃ because of low levels in the bird's captive diet of capelin (Mallotus villosus) was the cause of the MBD. Starting in mid-July every chick's diet was supplemented with 714 IU oral vitamin D₃/kg body weight per day, after which the number of birds developing MBD declined to a rate of 4.3%. This study characterizes the clinical, gross, radiographic, and histologic features of vitamin D₃-responsive MBD in young herons and egrets and provides evidence to support the recommendation that captive birds on a diet of capelin be supplemented with vitamin D₃, especially during growth.

Nutritional Secondary Hyperparathyroidism and Fibrous Osteodystrophy in a Captive African Penguin (Spheniscus demersus) Similar to Osteomalacia in Poultry

A 9-yr-old female black-footed African penguin (Spheniscus demersus) was presented for necropsy after a history of reproductive abnormalities, paresis of limbs, weakness, and sudden death. Postmortem examination revealed soft keel, collapsed rib cage with beading of the ribs, and bilateral parathyroid enlargement. Classic histologic lesions of fibrous osteodystrophy with osteomalacia were observed in the ribs, vertebrae, and to a lesser extent in the femur and tibiotarsus associated with hyperplasia of parathyroid glands. This represents the first report of nutritional secondary hyperparathyroidism in birds of the order Spheniciformes, most likely caused by low levels of calcium supplementation during egg laying. The reproductive abnormalities observed in this penguin and others from the same group (asynchronous egg-laying cycles, abnormal breeding behavior) were most likely exacerbated by the lack of an adequate photoperiod mimicking the natural daylight pattern.

Isolation of Salmonella spp. in cattle egrets (Bubulcus ibis) from Fernando de Noronha Archipelago, Brazil

The growth of the population of cattle egrets (Bubulcus ibis) in the archipelago of Fernando de Noronha constitutes a threat to public health and biological diversity because of their competition with and predation on native species and the possibility of transmission of pathogens to human beings, livestock and native wildlife. The aim here was to search for, isolate and identify serovars of Salmonella in clinically healthy local cattle egrets. Cloacal swabs were obtained from 456 clinically healthy cattle egrets of both sexes and a variety of ages. The swabs were divided into 51 pools. Six of these (11.7%) presented four serovars of Salmonella enterica subspecies enterica: Salmonella serovar Typhimurium; Salmonella serovar Newport; Salmonella serovar Duisburg; and Salmonella serovar Zega. One sample was identified as S. enterica subspecies enterica O16:y:-. Results in this study suggest that cattle egrets may be reservoirs of this agent on Fernando de Noronha and represent a risk to public health and biological diversity.

Interspecies differences in plasma concentrations of 25-hydroxyvitamin D3 and dermal Vitamin D synthesis of kiwi (Apteryx mantelli), tuatara (Sphenodon punctatus), and New Zealand sea lions (Phocarctos hookeri)

Vitamin D plays a central role in calcium homeostasis of most vertebrates, and is obtained in different species through diet, dermal synthesis, or a combination of both. The aim of this study was to determine the predominant routes of Vitamin D synthesis in three disparate species, brown kiwi (Apteryx mantelli), tuatara (Sphenodon punctatus), and New Zealand sea lions (Phocarctos hookeri). We surveyed plasma concentrations of 25-hydroxyvitamin D₂ and D₃, analysed environmental conditions and life history factors, and determined the ability of skin samples to synthesise Vitamin D₃ on exposure to ultraviolet-B radiation. There was variation in the plasma/serum 25-hydroxyvitamin D₃ concentrations between and within the species studied, with wild kiwi having the lowest concentrations and NZ sea lions the highest. Kiwi skin produced small but measurable amounts of Vitamin D₃, while tuatara skin produced Vitamin D₃ concentrations higher than that of kiwi. New Zealand sea lion skin produced the highest amount of Vitamin D₃ and differed from the other two species in this study in that Vitamin D₃ was present in skin before UV-B exposure. The results from this study show that all three species studied retained the ability to use both dietary and dermal sources of Vitamin D, although there was interspecies variation in the magnitude of dermal synthesis. Comparisons between these species show that there are differences in their Vitamin D pathways, but suggest that there are more factors contributing to these pathways than might be expected solely from life history characteristics.

THE EFFECT OF UVB RADIATION ON SERUM VITAMIN D AND IONIZED CALCIUM IN THE AFRICAN SPOONBILL (PLATALEA ALBA)

Metabolic bone disease (MBD) was diagnosed in two chicks produced by a captive breeding colony of African spoonbills (Platalea alba). The birds were housed indoor during the winter breeding season and had no access to natural sunlight. When the index cases occurred, the nesting birds and chicks had a mean 25-hydroxyvitamin D (25-OHD) concentration of 9.9 ± 2.7 nmol/L and a mean ionized calcium (iCa) concentration of 0.98 ± 0.12 mmol/L (winter pretreatment). For comparison purposes, serum was collected the following summer; mean 25-OHD was 20.8 ± 3.9 nmol/L and mean iCa was 1.32 ± 0.05 mmol/L (summer). During the following breeding season, ultraviolet B (UVB) lighting was provided to the flock, resulting in a mean 25-OHD of 19.0 ± 5.6 nmol/L and mean iCa of 1.23 ± 0.06 mmol/L (winter treatment 1). Both 25-OHD and iCa were significantly higher compared with winter pretreatment, and 25-OHD was not significantly different from summer, indicating that treatment during the winter months succeeded in increasing 25-OHD levels to summer levels. However, winter treatment 1 and summer iCa were significantly different. During the next breeding season (winter treatment 2), the birds were exposed to a light with higher UVB output. The mean 25-OHD of the flock was 16.5 ± 7.2 nmol/L, and the mean iCa increased to 1.34 ± 0.04 mmol/L. Both were comparable to summer values. Healthy chicks were hatched during both breeding seasons, and no further cases of MBD occurred during the course of the study. Provision of a UVB light source to captive African spoonbills maintained indoors during the winter months can increase 25-OHD and iCa to levels equivalent to those seen in the summer months, when birds have unrestricted access to natural sunlight. UVB lighting is recommended for all breeding spoonbills that do not have access to natural sunlight.

Causes of morbidity and mortality in free-living birds in an urban environment in Germany

Free-living birds are often presented to veterinarians at rehabilitation centers as well as in private practice. Information about disease processes and causes of death of indigenous free-living birds can aid the clinician in establishing proper treatment and in the assessment of potential zoonotic risks. For the present study, pathogens as causes of morbidity and mortality were determined by performing a complete necropsy on free-living birds presented to the Clinic for Birds and Reptiles of the University of Leipzig (Germany) that died shortly after admission or were euthanized due to an unfavorable prognosis. Over a 2-year period, 251 birds representing 13 families (Accipitridae, Apodidae, Columbidae, Corvidae, Falconidae, Fringillidae, Hirundinidae, Paridae, Passeridae, Picidae, Strigidae, Sturnidae and Turdidae) were examined. Trauma (62%), including several bite injuries inducing bacterial septicemia caused by Pasteurella multocida, was the most common cause of morbidity. Parasitic disease (18%) was mainly caused by Trichomonas gallinae, Eucoleus dispar and Syngamus trachea. Metabolic disease (13%), including fibrous osteodystrophy, was almost exclusively limited to juvenile specimens. Different Enterobacteriaceae including E. coli, Salmonella Typhimurium DT040 as well as Mycobacterium avium ssp. avium were identified as causal agents of primary bacterial disease (5%). Primary bacterial infection as cause of death or disease was of major importance in nestlings. Viral infections, mycoses and intoxication had minor significance as causes of morbidity.

When conservation management becomes contraindicated: impact of food supplementation on health of endangered wildlife

Understanding the conditions that force the implementation of management actions and their efficiency is crucial for conservation of endangered species. Wildlife managers are widely and increasingly using food supplementation for such species because the potentially immediate benefits may translate into rapid conservation improvements. Supplementary feeding can also pose risks eventually promoting undesired, unexpected, subtle, or indirect, and often unnoticed, effects that are generally poorly understood. For two decades, intensive food supplementation has been used in attempting to improve the breeding productivity of the Spanish Imperial Eagle, Aquila adalberti, one of the most endangered birds of prey in the world. Here, we examined the impact of this intensive management action on nestling health, including contamination, immunodepression, and acquisition of disease agents derived from supplementation techniques and provisioned food. Contrary to management expectations, we found that fed individuals were often inadvertently "medicated" with pharmaceuticals (antibiotics and antiparasitics) contained in supplementary food (domestic rabbits). Individuals fed with medicated rabbits showed a depressed immune system and a high prevalence and richness of pathogens compared with those with no or safe supplementary feeding using non-medicated wild rabbits. A higher presence of antibiotics (fluoroquinolones) was found in sick as opposed to healthy individuals among eaglets with supplementary feeding, which points directly toward a causal effect of these drugs in disease and other health impairments. This study represents a telling example of well-meaning management strategies not based on sound scientific evidence becoming a "contraindicated" action with detrimental repercussions undermining possible beneficial effects by increasing the impact of stochastic factors on extinction risk of endangered wildlife.

A importância da ordem Ciconiiformes na cadeia epidemiológica de Salmonella spp. para a saúde pública e a conservação da diversidade biológica

A diversidade biológica é representada por todas as unidades da natureza e sua conservação diz respeito à sobrevivência da própria espécie humana. Uma das ameaças à sua conservação são as doenças infecciosas que afetam a fauna, dentre as quais se podee incluir a salmonelose como uma das mais importantes, especialmente para a avifauna. Aves de topo de cadeia alimentar como os Ciconiiformes podem ser potenciais reservatórios e disseminadores da Salmonella spp. para outras espécies silvestres e também para populações humanas e animais domésticos, podendo causar prejuízos à saúde pública e ao meio ambiente. Objetivou-se descrever a infecção ou doença por Salmonella sp., o seu agente etiológico e sua ocorrência em Ciconiiformes, bem como demonstrar a importância destas aves na cadeia epidemiológica silvestre desta zoonose, verificando os riscos para a saúde pública e para a conservação da diversidade biológica.

Radiographic diagnosis of metabolic bone disease in captive bred mountain chicken frogs (Leptodactylus fallax)

Asymptomatic captive bred and wild-caught mountain chicken frogs (Leptodactylus fallax) were radiographed for evidence of metabolic bone disease (MBD). All 22 captive bred frogs had multiple folding fractures of long bones, decreased bone density, and cortical thinning, whereas none of the 11 wild-caught frogs had any radiographic evidence of MBD. These findings suggest that the nutritional requirements of L. fallax need to be examined for captive management purposes.

Calcium metabolism in birds

Calcium is one of the most important plasma constituents in mammals and birds. It provides structural strength and support (bones and eggshell) and plays vital roles in many of the biochemical reactions in the body. The control of calcium metabolism in birds is highly efficient and closely regulated in a number of tissues, primarily parathyroid gland, intestine, kidney, and bone. The hormones with the greatest involvement in calcium regulation in birds are parathyroid hormone, 1,25-dihydroxyvitamin D(3) (calcitriol), and estrogen, with calcitonin playing a minor and uncertain role. The special characteristics of calcium metabolism in birds, mainly associated with egg production, are discussed, along with common clinical disorders secondary to derangements in calcium homeostasis.