Mortality of four captive-born crested screamer chicks (Chauna torquata).

Crested screamers, a unique, mainly terrestrial avian species native to South America, are known to have a markedly high chick mortality rate in captivity, ranging from 61% to 94%; however, there is very limited information on this species' natural history within the literature, and even less about common diseases that affect them. Four captive-born crested screamer chicks (Chauna torquata) at a U.S. zoological institution died acutely from different causes over the course of 2.5 months. Although a hands-off approach was initially taken, each chick became acutely weak on exhibit and medical intervention was deemed necessary, but proved unsuccessful in all cases. Necropsy results of the chicks revealed various causes of death, including acute Escherichia coli colitis, aspiration pneumonia complicated by concurrent gastrointestinal Candidiasis, severe dehydration and emaciation, and acute amoebic gastroenteritis. No direct associations were found between these deaths and diet or husbandry; however, the limited literature on this topic suspects inadequate husbandry and immunosuppression to be the greatest cause of chick mortality in this species. The cases presented here are consistent with this hypothesis, but further exemplify the limited knowledge of this species and the need to optimize their survivability and proliferation in captivity.

Suspected cholecalciferol rodenticide toxicosis in avian species at a zoological institution.

Over a 2-month period, individual birds belonging to species in multiple avian families, including Bucerotidae, Sturnidae, Columbidae, Corvidae, and Anatidae, were presented to the Animal Care Center at the Phoenix Zoo for emergency medical care. Common clinical findings were subdued behavior, weight loss, and an inability to fly. Biochemical abnormalities commonly included high calcium and uric acid concentrations and high to high-normal phosphorus concentrations. In cases in which necropsies were done, mineralization of organs often was present, frequently of the kidneys and cardiovascular system. Because of the high calcium and phosphorus concentrations, mineralization of tissues, cases representing multiple avian species, and the recent addition of rodent bait boxes containing cholecalciferol to the zoo's pest control program, a presumptive diagnosis of cholecalciferol toxicosis was made. Treatment most commonly consisted of daily fluid diuresis. These cases demonstrate that, although cholecalciferol is considered unlikely to cause relay toxicosis, primary toxicosis still should be considered in cases with sudden onset of nonspecific signs when exposure to cholecalciferol was possible.

Hemorrhagic and necrotizing hepatitis associated with administration of a modified live canine adenovirus-2 vaccine in a maned wolf (Chrysocyon brachyurus).

A 15-yr-old, female, maned wolf (Chrysocyon brachyurus) was euthanized after presenting semicomatose with severe, uncontrolled frank hemorrhage from her rectum 6 days following a routine physical examination and vaccination. Histopathology indicated severe hemorrhagic and necrotizing hepatitis with intranuclear basophilic inclusion bodies in the liver that were thought to be consistent with adenoviral infection. Further classification by polymerase chain reaction, immunohistochemical staining, virus isolation, and electron microscopy confirmed the etiologic agent to be canine adenovirus-2. A representative sample of the vaccine that had been used was submitted and sequenced along with the virus isolated from the maned wolf. The sequencing of the etiologic agent that had been isolated from the maned wolf was determined to be the same as the strain of virus used in the production of the modified live vaccine that had been administered 6 days prior to death. From this information, the diagnosis of vaccine-induced adenoviral hepatitis was made. This is the first confirmed case of vaccine-induced canine adenoviral hepatitis in a maned wolf.

Haemosporidian infection in captive masked bobwhite quail (Colinus virginianus ridgwayi), an endangered subspecies of the northern bobwhite quail.

The avian haemosporidian parasites (phylum Apicomplexa) are taxonomically diverse and cosmopolitan in distribution; infecting most bird families. Sources of concern are reports of clinical haemosporidian infections in birds kept as part of zoo and aviary collections. Recently, severe and acute mortality episodes have been reported in masked bobwhite quail (Colinus virginianus ridgwayi), an endangered subspecies from the American Southwest. Two hundred and five eggs of the captive flock held in Arivaca, Arizona, were hatched at a zoo in the American Southwest. Thirty-four sub-adult or adult animals had lesions associated with tissue phases of haemoparasites, especially vasculitis, ventricular leiomyositis and ulcerative pododermatitis. Molecular techniques applied to blood collected from the zoo's last twelve remaining animals resulted in the detection of a Plasmodium juxtanucleare-like and Haemoproteus sp. parasites. A Raven (Corvus corax), in a contiguous exhibit, was positive for the same P. juxtanucleare-like parasite, but remained asymptomatic for three years following detection. These findings indicate that other birds in the exhibit within the zoo premises could act as reservoirs. We conclude that haemosporidian infections could be a factor in the demise of the captive masked bobwhite quails housed at the zoo. We suggest that active surveillance for haemoporidian parasites should be incorporated as a precaution to ex situ conservation efforts of susceptible endangered species.

Caprine herpesvirus-2 in association with naturally occurring malignant catarrhal fever in captive sika deer (Cervus nippon).

Three female sika deer from a single captive herd were submitted for postmortem examination over a 139-day period. The first 2 deer submitted were reported to have lost body mass for 20 days to 1 month before euthanasia. One of these deer had diarrhea, the other had a crusting dermatitis on the nasal planum and inner aspects of both pinnae. The third hind did not have any signs of disease before it was found seizuring and was immediately euthanatized. Microscopically, all 3 animals had a lymphocytic vasculitis typical of malignant catarrhal fever (MCF), with the most severe lesions in the brain. All 3 deer were polymerase chain reaction (PCR) positive for caprine herpesvirus 2 (CpHV-2) and were negative for ovine herpesvirus 2 (OHV-2). Two healthy goats that were housed adjacent to the deer were also PCR positive for CpHV-2 and PCR negative for OHV-2. The CpHV-2, PCR amplicons from the hinds, and the 2 healthy goats had an identical single base polymorphism. A male sika deer that was housed with the hinds and a fawn from 1 of the hinds remained asymptomatic and were PCR negative for CpHV-2. This represents the first report of mortality with MCF-like lesions in association with CpHV-2.

Hemorrhagic disease in bighorn sheep in Arizona.

Two bighorn sheep from Arizona (USA) were submitted for necropsy. One was a Rocky Mountain bighorn (Ovis canadensis canadensis) and the other was a desert bighorn (Ovis canadensis mexicana). Both had lesions consistent with those of hemorrhagic disease (HD). Epizootic hemorrhagic disease virus (EHDV) type-2 and bluetongue virus (BTV) type-17, respectively, were isolated from the sheep tissues. To our knowledge, HD caused by either EHDV or BTV infection has not been documented previously in Arizona bighorn sheep.

Hemorrhagic disease in deer in Arizona.

Two mule deer (Odocoileus hemionus) and one white-tailed deer (Odocoileus virginianus) in Arizona (USA) were submitted for necropsy. Gross and microscopic lesions compatible with hemorrhagic disease (HD) were observed in all three deer. Epizootic hemorrhagic disease virus type 2 (EHDV-2) was isolated from two of the deer. To our knowledge, this is the first documentation of HD in deer in Arizona. Two of the mortalities were attributed to EHDV-2 infection.

Chytridiomycosis in native Arizona frogs.

Twenty-seven adult/sub-adult lowland leopard frogs (Rana yavapaiensis), two larval lowland leopard frogs, two adult Chirichahua leopard frogs (Rana chiricahuensis), and two adult canyon tree frogs (Hyla arenicolor) collected from populations experiencing mortality events at eight sites were found to have characteristic lesions of chytrid fungus infection (Batrachochytrium dendrobatidis). The mortalities occurred during December 1992 and between October and February in 1997-98 and December and February in 1998-99. Gross lesions varied from none to diffuse reddening of the skin of the abdomen, pelvic area, and legs. Microscopic lesions were characteristic of those previously reported for the disease and included diffuse epidermal hyperplasia, hyperkeratosis, and colonization of the keratinized layers of the epidermis by sporangia of the chytrid. Bacterial cultures did not yield a primary pathogenic agent. Virus isolation from frog tissues was negative. Batrachochytrium dendrobatidis was isolated from the skin of two of 10 R. yavapaiensis and one of two H. arenicolor cultured following necropsy. An additional nine of 11 clinically affected or dead R. yavapaiensis from the same locations, but not necropsied, were culture positive for B. dendrobatidis.