Primary amebic meningoencephalitis due to Naegleria fowleri in a South American tapir.

Naegleria fowleri, Acanthamoeba spp., and Balamuthia mandrillaris are known to cause fatal central nervous system (CNS) disease in human beings. N. fowleri causes acute, fulminating primary amebic meningoencephalitis (PAM), which generally leads to death within 10 days. Acanthamoeba spp. and B. mandrillaris cause chronic granulomatous amebic encephalitis, which may last for 8 weeks. Acanthamoeba spp. and B. mandrillaris also cause CNS disease in animals. N. fowleri, however, has been described only in human beings. This report is the first of PAM in an animal, a South American tapir. Dry cough, lethargy, and coma developed in the animal, and its condition progressed to death. At necropsy, lesions were seen in the cerebrum, cerebellum, and lungs. The CNS had severe, suppurative meningoencephalitis with many neutrophils, fibrin, plasma cells, and amebas. Amebas were 6.5 microns to 9 microns in diameter and had a nucleus containing a large nucleolus. Amebas in the sections reacted with a monoclonal antibody specific for N. fowleri in the immunofluorescent assay and appeared bright green.

Persistent papillomavirus infection in a cat.

A seven-year-old, neutered male, crossbred Persian was diagnosed as having persistent, cutaneous papillomavirus infection. The skin lesions consisted of round, multifocal-to-confluent, raised, black plaques on the neck, thorax, shoulders, and forelegs. Papillomavirus virions were demonstrated in negative-stained, electron microscopic preparations of homogenized skin lesions and within the nuclei of cells from the stratum granulosum. Avidin-biotin immunoperoxidase stains were positive for papillomavirus in the same cells. The cat was euthanized due to a clinical diagnosis o concurrent, severe, chronic pancreatitis.

Neuroaxonal degeneration in sheep grazing Sorghum pastures.

During the fall of 1992, 250 (10%) of 2,500 Rambouilet cross feeder lambs grazing Sorghum bicolor developed neurologic signs including weakness, ataxia, head shaking, knuckling of the fetlocks, inability to rise, and opisthotonos. One hundred fifteen (46%) of the affected lambs died. Twenty of the surviving lambs exhibited residual neurologic signs of ataxia when stressed. At the same time, 275 (25%) of 1,100 ewes grazing a nearby sudex pasture (S. sudanese x S. bicolor) gave birth to lambs that were weak and unable to rise. Newborn lambs exhibited extensor rigidity and opisthotonos when assisted to a standing position. The dystocias that occurred were due to lambs with contracted limbs (arthrogryposis). All affected lambs died or were euthanized. Histologic examination of the brains of 3 feeder lambs and 9 newborn lambs revealed similar microscopic lesions. The predominant change was the presence of focal axonal enlargements (spheroids) in the proximal segments of axons, which were restricted to the nuclei of the medulla, cerebellum, and midbrain. In addition, the spinal cord contained spheroids in the ventral horn gray matter of the 6 newborns examined. Ultrastructurally, the spheroids were composed of aggregates of neurofilaments, mitochondria, vesicular bodies, and dense bodies bounded by a thin myelin sheath. There was mild gliosis in the more severely affected animals of both groups. There was minimal Wallerian degeneration in the white matter adjacent to affected nuclei in the brain and the ventromedial and dorsolateral funiculi of the spinal cord. This is the first detailed report of Sorghum toxicity in sheep.

Inclusion body hepatitis in Gambel's quail (Callipepla gambelii).

An acute necrotizing hepatitis in 1- to 3-wk-old Gambel's quail (Callipepla gambelii) caused by an adenovirus is described. The infection caused high mortality in captive raised, orphan chicks at two wildlife rehabilitation facilities in Arizona (USA). Gross lesions varied from pale livers to multiple, pinpoint, white foci scattered throughout the livers. Microscopically, scattered foci of hepatocellular necrosis were present. Intact hepatocytes at teh periphery of necrotic foci had eosinophilic and basophilic intranuclear inclusion bodies.

Onchocerciasis in two dogs.

Although widely reported in cattle, horses, and other ungulates, onchocerciasis has only recently been reported in 1 dog. We report 2 additional dogs with onchocerciasis involving the palpebral conjunctiva, third palpebra, and sclera. Both dogs were evaluated because of ocular or periocular masses. Histologically, viable adult parasites were surrounded by minimal fibrosis and few macrophages. Pyogranulomas were often centered around degenerating or mineralized Onchocerca organisms. Onchocerciasis should be considered in the differential diagnosis of ocular or periocular nodules in dogs, particularly dogs from western states.

Pancreatic adenocarcinoma with osseous metaplasia in a ferret.

A poorly differentiated pancreatic adenocarcinoma with regional lymphatic, hepatic, enteric and pulmonary metastases was diagnosed in an adult European ferret (Mustela putoris furo). The ferret showed clinical signs including a progressive, marked abdominal enlargement owing to ascites. Microscopic findings included intralesional osseous metaplasia. Exocrine pancreatic neoplasms in ferrets are rarely reported compared with neoplasms with endocrine differentiation.