Paramyxovirus infection in caiman lizards (Draecena guianensis)

Three separate epidemics occurred in caiman lizards (Dracaena guianensis) that were imported into the USA from Peru in late 1998 and early 1999. Histologic evaluation of tissues from necropsied lizards demonstrated a proliferative pneumonia. Electron microscopic examination of lung tissue revealed a virus that was consistent with members of the family Paramyxoviridae. Using a rabbit polyclonal antibody against an isolate of ophidian (snake) paramyxovirus, an immunoperoxidase staining technique demonstrated immunoreactivity within pulmonary epithelial cells of 1 lizard. Homogenates of lung, brain, liver, or kidney from affected lizards were placed in flasks containing monolayers of either terrapene heart cells or viper heart cells. Five to 10 days later, syncytial cells formed. When Vero cells were inoculated with supernatant of infected terrapene heart cells, similar syncytial cells developed. Electron microscopic evaluation of infected terrapene heart cells revealed intracytoplasmic inclusions consisting of nucleocapsid strands. Using negative-staining electron microscopy, abundant filamentous nucleocapsid material with a herringbone structure typical of the Paramyxoviridae was observed in culture medium of infected viper heart cells. Seven months following the initial epizootic, blood samples were collected from surviving group 1 lizards, and a hemagglutination inhibition assay was performed to determine presence of specific antibody against the caiman lizard isolate. Of the 17 lizards sampled, 7 had titers of < or =1:20 and 10 had titers of >1:20 and < or =1:80. This report is only the second of a paramyxovirus identified in a lizard and is the first to snow the relationship between histologic and ultrastructural findings and virus isolation.

Naturally occurring GM2 gangliosidosis in two Muntjak deer with pathological and biochemical features of human classical Tay-Sachs disease (type B GM2 gangliosidosis)

Two juvenile sibling male Muntjak deer (Muntiacus muntjak) with histories of depression, ataxia, circling and visual deficits were studied. Cerebrospinal fluid analyses revealed vacuolated macrophages that contained long parallel needle-like intracytoplasmic inclusions. Light microscopically, nerve cell bodies throughout the brain, ganglion cells within the retina and neurons in the myenteric plexuses were variably swollen and had pale granular to finely vacuolated eosinophilic cytoplasm. Neuronal cytoplasm stained specifically with sudan black and Luxolfast blue stains. Within the brain there were occasional axonal spheroids, foci of astrogliosis and scattered microglial cells with abundant pale foamy cytoplasm. Electron microscopy of the brain and retina revealed numerous neurons and ganglion cells, respectively, with multiple membrane-bound structures that contained compact electron-dense membranous whorls and fewer parallel membranous stacks. Thin layer chromatography of total lipid extracts of the cerebral cortex of both cases revealed massive accumulation of G(M2) ganglioside. Crude kidney extracts of the two affected deer were able to hydrolyze 4-methylumbelliferyl beta-GlcNAc, but not 4-methylumbelliferyl beta-GlcNAc-6-sulfate, indicating the defect of beta-hexosaminidase A. Cellogel electrophoresis of the kidney extracts also revealed the deficiency of beta-hexosaminidase A in the two deer. It is concluded that these two deer had the biochemical lesion identical to that of human type B G(M2) gangliosidosis (classical Tay-Sachs disease).

Immunohistochemical detection of p53 tumor suppressor gene protein in canine epithelial colorectal tumors

Eighty canine epithelial colorectal tumors obtained by excisional biopsy were evaluated immunohistochemically for p53 tumor suppressor gene protein. Dogs in the study average 6.9 years of age (range, 1-12.5 years). A standard avidin-biotin immunohistochemical protocol incorporated a polyclonal antibody of rabbit origin (CM-1) as the primary antibody. Positive staining was observed within all subcategories of lesions, including hyperplastic polyps 1/2 (50%), adenomas 14/29 (48%), carcinomas in situ 9/22 (41%), adenocarcinomas 3/4 (75%), and invasive carcinomas 8/23 (35%). A total of 35/80 (44%) positive tumors wee identified. Fifteen of 31 (48%) benign tumors labeled for p53 protein compared to 20/49 (41%) malignant tumors. Survival data was available for 57/80 (71%) dogs. The average age of dogs within the group with survival data was 4.4 years. Males predominated 34/57 (60%). Mean survival time was 20.6 months. There was no significant difference in survival time between dogs grouped according to p53 immunoreactivity, cellular stain location, or tumor site. A statistically significant increase in survival time was observed between dogs with clean surgical margins and those without (P < 0.018) and for dogs with adenomas or carcinomas in situ over dogs with invasive carcinomas (P < 0.02). In this study, the overall greater positive staining frequency of benign lesions compared to malignant lesions is contrary to data derived from similar immunohistochemical analyses of human tumors and is incongruous with the theorized late-stage participation of the p53 protein in the development of human colorectal cancers. The results of this study suggest that if the p53 tumor suppressor gene protein is involved in the progression of canine colorectal tumors, it may play a relatively early role, possibly analogous to the early appearance of p53 overexpression in precancerous lesions of human ulcerative colitis. Immunohistochemical detection of p53 was not useful prognostically.

Demonstration of common and stage-specific anti-Hepatozoon mocassini antibodies in experimentally infected unnatural lizard hosts

This study examines the immunological response to Hepatozoon mocassini in lizards. Three lizard species were infected experimentally with H. mocassini. Baseline and post-infection (PI) sera were assayed for anti-H. mocassini meront and gametocyte antibody by immunohistochemistry and IFA. Seroconversion occurred at 38 d PI with endpoint IFA titers of 1:64. Antisera from non-parasitaemic and parisitaemic lizards exhibited similar affinities for merozite and gametocyte antigens. Antibody specific for the membranes of gametocyte-infected erythrocytes was demonstrated exclusively in parasitaemic lizards. The results demonstrate that lizards infected with snake haemogregarines mount an antibody response with common and stage-specific components.

Efficacy of acyclovir against herpesvirus infection in Quaker parakeets

We evaluated the efficacy of acyclovir against experimentally induced herpesvirus infection (Pacheco's parrot disease) in Quaker parakeets. Thirty-two of 40 birds were challenge-exposed with 0.1 ml of a suspension of herpesvirus (10(4) median cell culture infective doses [CCID50]) given IM. Treatment with acyclovir was started 24 hours later and was continued for 7 days. The birds were allotted to 5 groups of 8 birds each. There was a considerable difference in mortality between groups 1-5. Of 8 bird in each group, 6 died in group 1 (control), 1 died in group 2 (gavage), 3 died in group 3 (low dose, IM), 4 died in group 4 (high dose, IM), and none died in group 5 (contact controls). There was a significant (P = 0.023) difference in mortality between groups 1 and 2, thus the oral form of acyclovir administered by gavage was the most efficacious therapeutic regimen. Clinical signs and death occurred after discontinuation of acyclovir in groups 2 and 3, whereas the mean time of death for the control group was 6 days after challenge exposure. Herpesvirus was recovered by inoculation of chick embryo cell culture with pooled tissue suspensions from all birds that died. Histologic evidence of herpesvirus infection was found in most birds that died, with the control group having the most severe lesions. Surviving Quaker parakeets were transferred to cages with seronegative Quaker parakeets with no known exposure to herpesvirus. There have been no deaths attributable to herpesvirus infection in a period exceeding 2 years.

Unilateral congenital aneurysm of the jugular, linguofacial, and maxillary veins in a dog

A 5-month-old female Gordon Setter was examined because of a soft, fluctuant, subcutaneous swelling in the right submandibular region. Clinical problems were not associated with the mass. Cytologic examination and blood gas analysis of an aspirate from the mass confirmed its contents to be venous blood. Venous angiography delineated a fusiform dilatation of the right jugular, maxillary, and linguofacial veins, with no evidence of obstruction or anomalous venous return to the heart. The dilated segments were surgically excised, and the tissue was submitted for histologic examination. The clinical, radiographic, and histologic features of this lesion supported the diagnosis of congenital venous aneurysm.

Cytologic Features of a Meningioma in a Dog

Meningiomas are one of the most common nervous system tumors in dogs. They are mostly solitary, benign, intracranial tumors of the transitional type. Tentative diagnosis can usually be made on historical data, clinical and neurological signs, and radiographs, with an antemortem diagnosis confirmed by exploratory surgery and histologic evaluation of biopsy. The literature contains many reports of the gross, histological and ultrastructural morphology of canine meningiomas, but little on the cytologic features of these tumors. This report describes the cytologic appearance of an intracranial meningioma in a 9-year-old Miniature Schnauzer.

Protothecosis in two cats

Protothecosis was diagnosed in 2 cats from Florida with nodular skin lesions. Microscopically, lesions were composed of macrophages and multinucleated giant cells arranged in solid sheets in the dermis and subcutis. In both cats, characteristic algal endospores identified as Prototheca wickerhamii were observed within the cytoplasm of infiltrating cells.