Fatal toxoplasmosis in a bald eagle (Haliaeetus leucocephalus).

Toxoplasma gondii tachyzoites were identified in the myocardium of a bald eagle (Haliaeetus leucocephalus) that died of necrotizing myocarditis. The diagnosis was confirmed by immunohistochemical staining with T. gondii-specific polyclonal antibodies. This is a new host record for T. gondii.

Balloon cell melanoma in three dogs: a histopathological, immunohistochemical and ultrastructural study.

Balloon cell melanoma, a variant of malignant melanoma, has been reported on rare occasions in animals and is uncommon in man. Such tumours have variable numbers of large, round to polygonal cells with abundant, clear, often vacuolated cytoplasm containing fine melanin granules and variable amounts of lipid. This report describes balloon cell melanomas in three dogs. Immunohistochemically, these tumours showed reactions similar to those of human melanomas when tested with antibodies against S-100 protein, neuron-specific enolase (NSE) and vimentin. Electron microscopically, numerous heterogeneous melanosomes were demonstrated in the balloon cell cytoplasm of one tumour. Although balloon cell melanoma apparently occurs infrequently in dogs, it should always be considered in the differential diagnosis of neoplasms containing clear cells.

Bacteriologic and histologic features in mice after intranasal inoculation of Brucella melitensis.

OBJECTIVE: To characterize effects of intranasal inoculation of virulent Brucella melitensis strain 16M in mice. ANIMALS: Female Balb/c mice, 6 to 8 weeks old. PROCEDURE: Studies were designed to elucidate gross morphologic lesions, bacterial burden in target organs, and histologic changes in tissues following experimental intranasal inoculation of mice with B melitensis 16M, which could be used to characterize a model for testing vaccine efficacy. RESULTS: Measurable splenomegaly was evident at 3 and 7 weeks after inoculation. A demonstrable increase in splenic colony-forming units (CFU) from infected mice increased over time with increasing dose when comparing inocula of 10(3), 10(4), and 10(5) CFU. Recovery of brucellae from the lungs was possible early in infection with 10(1), 10(3), and 10(5) CFU, but only the group inoculated with 10(5) CFU consistently yielded quantifiable bacteria. At a dose of 10 CFU, few organisms were located in the spleen. Bacteria were recovered up to 140 days after inoculation in mice given 10(3) CFU. At an inoculum of 10(5) CFU, bacterial counts were highest early in infection. Histologic examination of tissues revealed an increase in white pulp and marginal zone in the spleen and lymphohistiocytic hepatitis. CONCLUSION AND CLINICAL RELEVANCE: Changes in the spleen and liver increased with increases in dose and with increased time following intranasal inoculation with B melitensis 16M. Surprisingly, histologic changes were not observed in the lungs of inoculated mice.

Chronic emesis caused by a nematode-induced gastric nodule in a cat.

A spirurid nematode-induced gastric nodule was believed to be responsible for chronic gastric irritation and vomiting in a domestic short-hair cat. Clinical improvement was noticed following surgical removal of the parasitic nodule in the wall of the pylorus. Morphologic characteristics of the parasite were most consistent with Spirocerca lupi. Infection with Spirocerca lupi is most commonly reported in Canids, often resulting in chronic granulomatous disease of the distal portion of the esophagus. In some animals, the lesions transform into fibrosarcomas and osteogenic sarcomas.

A study on the use of male animal models for developing a live vaccine for brucellosis.

To study the safety of Brucella melitensis WR201, a live vaccine candidate, we compared the course of infection of this strain with that of virulent 16M in male BALB/c mice. At various times after oral immunization with strains WR201 or 16M, lungs, liver, spleen, testis, epididymis, inguinal and cervical lymph nodes were removed. Tissues were divided for microbiologic culture and histopathological examination. WR201 infection in male BALB/c mice had lower intensity and shorter duration than infection caused by virulent 16M. Pathological examination of testis and epididymis revealed no inflammation following strain WR201 immunization. In contrast, animals given virulent 16M strain had substantial inflammation in infected tissues. These data confirm the marked attenuation of WR201 relative to 16M. In addition, these studies suggest that male mice may be useful to assess the safety of live, attenuated Brucella vaccine candidates.

Hermaphroditism in a Sprague-Dawley rat.

A spontaneous case of unilateral true hermaphroditism was observed during the routine necropsy of a 9-week-old presumed female Sprague-Dawley rat on a repeat-dose toxicity study. There were no drug-related effects observed. True hermaphroditism is rare in rats, and despite the large numbers of rats examined annually, few cases are reported in the literature.

Atrioventricular valvular angiectasis in Sprague-Dawley rats.

Subendothelial heart valve angiectasis has been reported in cows, dogs, pigs, rats, mice, and in human fetuses and newborns. We observed a high incidence (62 in 208 animals examined) of spontaneous angiectasis on the atrioventricular (AV) valves in 10- to 40-week-old Sprague-Dawley rats. The angiectasis was observed predominately on the septal cusp of the right AV valve and located near the AV ostium in 57 of 62 animals. Of the remaining 5 valvular angiectases, 2 were present on the parietal cusp of the right AV valve and 3 were on the left AV valve. The angiectases were single or multiple, ranging from 40 to 300 microm in diameter and were characterized by light microscopy as blood-filled dilatations lined by endothelium. Spontaneously occurring abnormalities in normal laboratory animals, such as the spontaneous valvular angiectasis reported here, need to be differentiated from drug-related lesions.

Ossifying fibroma in a miniature rex rabbit (Oryctolagus cuniculus).

In humans and animals, ossifying fibroma is a benign neoplasm that most frequently affects the mandible, often resulting in cosmetic deformities and malocclusion. It is considered rare in animals and most frequently affects young horses. A surgical biopsy of a solitary mass located beneath the gingiva in the right maxillary region, which had overgrown teeth and expanded the adjacent hard palate from a 6-year-old miniature Rex rabbit was submitted for light microscopic examination. The submitted incisional biopsy specimen was pale pink, firm, and nodular. Histopathologically, the neoplasm was composed of fibroblastic cells separated by abundant collagen. The neoplastic cells were interwoven with osteoblasts surrounding islands of mineralized, bony matrix containing few, widely spaced, often empty, lacunae. Minimal inflammation was present. Based on the histopathologic features, the tumor was diagnosed as an ossifying fibroma. To our knowledge, this is the first report of an ossifying fibroma in a rabbit.

Congenital bronchiolo-alveolar airway malformation in a cynomolgus macaque (Macaca fascicularis).

Pulmonary congenital anomalies in animals are rare. Previously reported malformations include accessory lung formation, pulmonary hypoplasia, pulmonary agenesis, and various forms of hamartoma. Congenital bronchiolo-alveolar airway malformation, a new entity, is described in a 1-day-old male cynomolgus macaque. This neonate experienced breathing difficulties shortly after birth and died while therapy was being administered. Grossly, the right lung was markedly increased in size, firm, and pink. Histopathologically, sections of right lung showed irregular bronchiole-like and alveolus-like structures. There was marked widening of alveolar septae by loosely arranged mesenchymal cells and many centrally located capillaries. Alveoli were lined by cuboidal epithelial cells. There were scattered islands of immature cartilage. A grossly enlarged lung containing bronchiole-like and alveolus-like structures, immature cartilage islands, and many capillaries within alveolar septae on histopathologic examination, is inconsistent with previously described congenital pulmonary anomalies in animals and humans.

Morbilliviral dermatitis in seals.

A juvenile female hooded seal (Cystophora cristata) and a juvenile male harp seal (Phoca groenlandica) stranded separately on the New Jersey (USA) coast and were taken to a marine mammal rehabilitation center. Both were lethargic and emaciated, had dermatitis, and died. Histologic skin lesions in the seals were similar and consisted of epidermal and follicular epithelial hyperplasia, hyperkeratosis, degeneration, and necrosis. The most distinctive finding was extensive syncytial zones bounded superficially by hyperkeratosis and deeply by hyperplastic basal cells. Eosinophilic intracytoplasmic inclusion bodies were present in epithelial cells. Morbilliviral antigen was demonstrated in the skin lesions by immunohistochemistry. Phocine distemper virus was detected in the skin by reverse transcription polymerase chain reaction and a phocine distemper virus-specific probe using the Southern blot technique. This is the first report of morbilliviral dermatitis in marine mammals.

An oral choristoma in a foal resembling hairy polyp in humans.

A neonatal foal was presented with a 6.5-cm pedunculated mass arising from the upper deciduous incisors. The distal end was soft and covered by haired skin, whereas the proximal end was firm, covered with mucosal epithelium, and at the point of transection contained a fully developed tooth. Microscopically, the mass was covered by epidermis and mucosal epithelium and the remaining portion of the mass consisted of mature collagen, nonneoplastic fat and smooth muscle, and a single tooth within a bony socket. The mass is consistent with an oral choristoma and has features similar to those described for hairy polyp in humans.

Histopathology of experimental plague in cats.

Formalin-fixed paraffin-embedded archival tissues of seven adult cats of both sexes that died after being experimentally infected with Yersinia pestis were examined light microscopically to characterize the lesions. The cats were exposed in two groups using two routes of infection: ingestion of Y. pestis-infected rodent or a subcutaneous injection of Y. pestis to simulate a flea bite. Immunohistochemistry was performed on tissues from all organ systems from a representative cat from each group to determine the distribution of Y. pestis bacilli during infection. In all seven cats, bubonic plague lesions were seen. The lesions of pneumonic plague were present in two cats. Septicemic plague was confirmed in all seven cats by bacteriologic culture. Aggregations of bacteria were seen in lymphoid tissue in all cats and in lung tissues from the two cats with pneumonic plague. The most consistent histologic finding was necrosuppurative inflammation in the lymph nodes. Invariably, Y. pestis bacteria were present in large numbers at affected sites. Orally infected cats had more numerous lesions in the lymph nodes of the head and neck regions. These experimentally induced cases of feline plague document that cats are unique among carnivores in exhibiting bubonic, pneumonic, and septicemic plague following exposure to Y. pestis. The lesions of the orally infected cats were consistent with those previously described for naturally occurring Y. pestis infections in cats and corroborate the contention that cats most commonly contract plague by eating Y. pestis-infected rodents and not via flea bite. The histopathology of Y. pestis disease in these cats is comparable to that described for human plague.

Impaired control of Brucella melitensis infection in Rag1-deficient mice.

After intranasal inoculation, Brucella melitensis chronically infects the mononuclear phagocyte system in BALB/c mice, but it causes no apparent illness. Adaptive immunity, which can be transferred by either T cells or antibody from immune to naive animals, confers resistance to challenge infection. The role of innate, non-B-, non-T-cell-mediated immunity in control of murine brucellosis, however, is unknown. In the present study, we documented that BALB/c and C57BL/6 mice had a similar course of infection after intranasal administration of 16M, validating the usefulness of the model in the latter mouse strain. We then compared the course of infection in Rag1 knockout mice (C57BL/6 background) (referred to here as RAG-1 mice) which have no B or T cells as a consequence of deletion of Rag1 (recombination-activating gene 1), with infection in normal C57BL/6 animals after intranasal administration of B. melitensis 16M. C57BL/6 mice cleared brucellae from their lungs by 8 to 12 weeks and controlled infection in the liver and spleen at a low level. In contrast, RAG-1 mice failed to reduce the number of bacteria in any of these organs. From 1 to 4 weeks after inoculation, the number of splenic bacteria increased from 2 to 4.5 logs and remained at that level. In contrast to the consistently high numbers of brucellae observed in the spleens, the number of bacteria rose in the livers sampled for up to 20 weeks. Immunohistologic examination at 8 weeks after infection disclosed foci of persistent pneumonia and large amounts of Brucella antigen in macrophages in lung, liver, and spleen in RAG-1, but not C57BL/6, mice. These studies indicate that T- and B-cell-independent immunity can control Brucella infection at a high level in the murine spleen, but not in the liver. Immunity mediated by T and/or B cells is required for clearance of bacteria from spleen and lung and for control of bacterial replication in the liver.

Molecular genetic evidence of a novel morbillivirus in a long-finned pilot whale (Globicephalus melas).

A long-finned pilot whale with morbilliviral disease was stranded in New Jersey. An immunohistochemical stain demonstrated morbilliviral antigen. Reverse transcriptase-polymerase chain reaction for morbillivirus P and N genes was positive. Novel sequences most closely related to, but distinct from, those of dolphin and porpoise morbilliviruses suggest that this virus may represent a third member of the cetacean morbillivirus group.