Cutaneous papillomatosis associated with papillomavirus infection in a dog.

A 7-year-old female Kerry blue terrier dog developed 20 cutaneous nodules, up to 4 mm in diameter, over the body. Light and electron microscopy demonstrated that they were virus-associated inverted papillomas and they are described because canine skin viral papillomas have not been frequently reported.

Necrotic colitis associated with Entamoeba histolytica infection in a cat.

A 3-year-old Persian cat developed bloody diarrhoea. On histological examination, a marked necrotic colitis with a large number of invading protozoan parasites was observed. The protozoan was identified as Entamoeba histolytica by light and electron microscopy. This is the first report describing spontaneous amoebiasis in cats.

Isolation of Mycoplasma hyorhinis and Mycoplasma arginini from the ears of pigs with otitis media.

Mycoplasmas were isolated from the middle ears and nasal cavities of clinically ill, young pigs that were slaughtered due to an unfavourable prognosis. The isolation rates of Mycoplasma hyorhinis were 27 of 43 (62.8 per cent) from the auditory tube, 22 of 43 (51.2 per cent) from the tympanic cavity, and 15 of 25 (60.0 per cent) from the nasal cavity. M arginini was also recovered at rates of 11 of 43 (25.6 per cent) from the auditory tube, 7 of 43 (16.3 per cent) from the tympanic cavity, and 9 of 25 (36.0 per cent) from the nasal cavity. Dual infections with M hyorhinis and M arginini occurred in these sites in some cases. M hyorhinis was isolated from 16 (80.0 per cent) of 20 pigs with otitis media diagnosed histologically, and from two (25.0 per cent) of eight pigs without this condition. The isolation rate was significantly different (P < 0.05) between the groups, suggesting either that the organism triggers development of the disease of the ear or that the agent(s) or factors responsible for otitis media in the pigs created favourable conditions at this site for colonisation by M hyorhinis.

Detection of Mycoplasma hyorhinis in porcine eustachitis.

Pathologic study of the ear was performed on 179 young swine, ranging in age from 1 day to 18.6 weeks. Histologically, eustachitis was the most common and its inflammatory reaction appeared to precede otitis. Immunohistochemically, Mycoplasma hyorhinis (Mhr) antigens were detected on the luminal surface of the auditory epithelia in 19 of 179 cases (10.6%). All the cases, positive for Mhr antigens, were associated with an acute eustachitis. Ultrastructural examination of two piglets confirmed these immunohistochemical data. The present results indicate that Mhr may be a primary cause of acute eustachitis in young swine.

An immunohistochemical and ultrastructural study on age-related astrocytic gliosis in the central nervous system of dogs.

The pattern of astrocytic gliosis (AG) was examined in 2-month-old to 18-year-old dogs using glial fibrillary acidic protein (GFAP) immunohistochemistry and electron microscopy. Coronal sections from various levels of the central nervous system (CNS) were stained with hematoxylin & eosin, Luxol Fast Blue, Nissl, and Bodian in addition to GFAP. A consistent pattern of age-related AG was observed in the dogs. The white matter, cortico-medullary junction, and subcortical nuclei in the cerebrum, central nuclei in the cerebellum, various nuclei in the brain stem, and grey matter of the spinal cord showed even and intense GFAP staining. AG was also prominent in the cerebral and cerebellar cortices and thalamus. Moderate AG was observed in the hippocampus and white matter of the cerebellum and spinal cord. Electron microscopy demonstrated increased number of profiles of degenerative neural components in the vicinity of hypertrophic astrocytes in the cerebral cortex of the aged dogs. Moderate to severe AG was consistently shown in the CNS of the aged dogs. In contrast, young normal dogs showed minimum amounts of GFAP-positive astrocytes in the CNS. These findings suggest that the observed AG in the CNS of the dogs is a morphological expression of aging.

Topographic relationship between senile plaques and cerebrovascular amyloidosis in the brain of aged dogs.

The distributions of senile plaques (SP) and cerebrovascular amyloidosis (CA) were studied by employing thioflavin S and modified Bielschowsky stains, and beta-protein immunohistochemistry on serial sections of the brains of aged dogs older than 10 years. Mature and perivascular plaques, both of which contained compact amyloid deposits, always showed a close topographic relationship to CA. In contrast, the majority of diffuse plaques showed no topographic relationship to CA. Cell bodies of neurons and/or glia were almost always involved in the diffuse plaques. In addition, beta-protein immunohistochemistry demonstrated amyloid deposits on the periphery of occasional neurons. These findings suggest that different mechanisms may be involved in the development of the different subtypes of SP in the brains of aged dogs.

Vitamin D toxicosis in cats: natural outbreak and experimental study.

A pathological study on 5 of 21 cats affected naturally with systemic calcinosis was performed. The animals ranged in age from 1 to 9 years. Hematology and serum chemistry analyses showed the elevated values of phosphorus, blood urea nitrogen and serum creatinine. X-ray examination disclosed the increased density of systemic bones. Histologically, marked calcification was present at the vascular walls of almost all the organs including the lungs, trachea, kidneys, heart, aorta, alimentary tracts, choroid plexus and bones. In the lungs, kidneys and stomach, the calcified lesions were associated with deposition of oxalate crystals. Serum chemistry showed more elevated values of 25-hydroxycholecalciferol (vitamin D) of the affected cats than the normal level. Retrospective examination revealed that these cats had been fed the commercial pet foods containing a large amount of vitamin D (6,370 IU/100 g diet) from their young age, and its value was about ten times as much as that of the control food (680 IU/100 g diet). Pathological changes found in the cats from the experimental vitamin D3 toxicosis were similar to those in the natural cases. In addition, tissue levels of calcium, phosphorous and zinc in the lungs and kidneys were markedly elevated in both natural and vitamin D-intoxicated cases. These findings suggest that long-term feeding of the pet food containing excessive vitamin D was responsible for the outbreak of the systemic calcinosis in the cats.

Hepatic encephalopathy associated with acquired portosystemic shunts in a dog.

An 8-month-old dog with a history of gastrointestinal disturbances and neurological signs was presented with hyperammonemia. Necropsy revealed ascites, portosystemic collaterals, and an irregularly surfaced small liver. Histologically, there were diffuse neuronal necrosis and focal spongiform changes in the brain, and marked fibrosis in the liver. Hepatic encephalopathy was diagnosed.

Demonstration of Mycoplasma hyorhinis as a possible primary pathogen for porcine otitis media.

A study of the pathology of the ear was performed on 479 pigs ranging in age from 1 day to 1 year. Histologically, 364 (76.0%) of 479 pigs were affected with otitis. Eustachitis was the most common and preceded an inflammation of other sites of the ear, and an acute eustachitis occurred from as early as 1 week of life. Immunohistochemical examination of frozen cryostat sections revealed Mycoplasma hyorhinis (Mhr) antigens on the luminal surface of the eustachian epithelia in 14 (50.0%) of 28 piglets examined. All the pigs positive for Mhr had an acute eustachitis. Ultrastructural examination on the auditory tubes with positive immunostaining disclosed many mycoplasmas among the cilia. Mhr was isolated from the auditory tubes and tympanic cavities of 19 (67.9%) and 16 (57.1%) of 28 piglets examined, respectively. Porcine otitis media may be caused primarily by Mhr infection in the auditory tube.

Pathogenesis of pancreatic atrophy by avian influenza a virus infection.

Specific-pathogen-free (SPF), 2-day-old chicks were inoculated with type A influenza virus (A/whistling swan/Shimane/499/83/(H5N3)) into their caudal thoracic air sac. The original isolate of the virus was of low virulence (ICPI 0. 20 to 0.40), and was passaged 10 times through the respiratory organs of SPF chicks. Most of the chicks inoculated with the passaged virus (strain 499) showed respiratory and alimentary signs. Three of 30 chicks died on days 2, 6 and 7 post-inoculation (p.i.). Almost half of the infected chicks showed poor growth, and the variation of body size in the flock became prominent from day 10 p.i. Infected chicks consistently had pathological changes in the pancreas, liver, kidneys and respiratory tracts, and occasionally in the brain, duodenum and bone marrow. Positive immunoreaction to avian influenza virus (AIV) antigen and recovery of the virus persisted for longer period in the pancreas than in other organs. The pancreatic lesions were caused by a direct, lytic virus infection of the acinar cells and contributed to poor growth of the chicks.

Type C Niemann-Pick disease in a boxer dog.

Pathological and biochemical studies were performed on a 9-month-old boxer dog with progressive neurological abnormality. Histological examination revealed marked neuronal storage throughout the central nervous system and histiocytic storage in the reticuloendothelial system. Ultrastructurally, the neuronal storage consisted of accumulation of concentric membranous inclusions and clusters of dense bodies. The biochemically unesterified cholesterol content was high in the liver and spleen. The brain showed increased levels of lactosylceramide and two gangliosides, GM3 and GM2. These findings indicate that this dog was affected with a heterogeneous lipid storage disease similar to the human Niemann-Pick type C disease.

Bovine undifferentiated alveolar rhabdomyosarcoma and its differentiation in xenotransplanted tumors.

At necropsy, a 7-year-old Holstein cow, clinically diagnosed via rectal palpation as having malignant abdominal neoplasia was found to have many metastatic tumors of various sizes in the abdominal and thoracic cavities and in the liver, lung, kidney, adrenal, uterus, and lymph nodes. These tumors were examined by histologic and immunohistochemical methods using anti-human myoglobin, anti-bovine myoglobin, and anti-desmin sera. Tumors were diagnosed as undifferentiated alveolar rhabdomyosarcomas. The tumors in the abdominal and thoracic cavities differed histologically from the metastases in organs. The former tumors consisted of only undifferentiated cells, most of which did not stain positively for desmin or myoglobin. The metastatic tumors contained a few rhabdomyoblastic cells that stained positively for desmin and myoglobin. Tumors tissues from the cow were transplanted and propagated through six passages in athymic nude mice. After one passage, the transplanted tumor histologically resembled those from the abdominal serosa and consisted of cells with scanty cytoplasm with an alveolar arrangement. Cells from this tumor stained positively for desmin and negatively for myoglobin. After two passages through nude mice, tumor cells were of two distinct histologic types: those cells with scanty cytoplasm and elongated cells with plentiful eosinophilic cytoplasm. Both of these cells stained positively for both desmin and myoglobin. After six passages, cross striations were detected in neoplastic cells by electron microscopy. These findings illustrate that a highly undifferentiated bovine rhabdomyosarcoma, in which most of the cells in the original tumor lacked desmin and myoglobin, became better differentiated and stained positively for desmin and myoglobin after serial transplantation in nude mice.