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SUMMARY

A sublethal dose of ethylene glycol was administered orally to 3 groups of dogs; dogs of a control group were given distilled water instead. Renal cortical biopsy samples were obtained from dogs of experimental and control groups at various times after treatment. Tissue was examined by use of light microscopy and transmission electron microscopy. In dogs of the control group, the light and electron microscopic appearances of tissue were within normal limits at all sample collection hours. In dogs of the experimental groups, renal corpuscular structure remained within normal limits by use of light and electron microscopy throughout the study, though morphologic change was seen in other structures of the cortex. Light microscopic lesions first appeared at 12 hours, and were similar to those reported in the literature. Ultrastructural lesions were first observed in the 5-hour samples, and similar to the light microscopic lesions, were most common in the proximal convoluted tubules (pct). Initial pct cellular changes included vacuolization of cells and distention of the parabasal extracellular spaces; pct cellular lesions seen in later-hour samples included formation of apical buds and cellular rupture. Internalization or sloughing of the pct brush border was not observed. Distal convoluted tubules (dct) were frequently dilated and/or packed with cellular debris. A few dct cells had degenerative or necrotic changes. In pct and dct, abnormal cells were frequently flanked by normal or nearly normal cells. During later hours, a few cells with types of changes first observed in early hours continued to be observed, implying ongoing response of cells to the toxin.

Free access
in American Journal of Veterinary Research

Summary

Data were collected from 104 Minnesota swine farms quarantined for pseudorabies virus (prv) infection. Each herd was serologically evaluated for the presence of antibodies to prv in finishing pigs. Herd management practices, swine housing design, and disease profiles were described for each farm. Multiple logistic regression analysis was used to determine which factors were associated with circulation of prv in the finishing pigs of farrow-to-finish farms. Sixty-seven (64%) of the herds had no serologic evidence of prv circulation in the finishing section, whereas 37 herds (36%) contained at least one prv seropositive finishing pig. The odds of a given finishing herd being seropositive for prv were 2.85 times higher if the finishing pigs were housed in confinement (P = 0.01), 2 times higher if Actinobacillus (Haemophilus) pleuropneumoniae was a clinical problem in the herd (P = 0.03), 1.36 times less for each year that passed since the herd quarantine was issued (P = 0.01), 1.74 times higher if clinical signs of prv were reported (P = 0.04), and 1.52 times higher if animal protein was included in at least one of the rations (P = 0.08).

Free access
in Journal of the American Veterinary Medical Association

Summary

Strategies for the elimination of pseudorabies virus (prv) from swine herds include test and removal, offspring segregation, and depopulation/repopulation. The prevalence of prv in a herd is a major factor in selection of the most appropriate strategy. The purpose of the study reported here was to describe the prevalence of prv in adult swine in prv quarantined herds in Minnesota, and to determine herd factors associated with the seroprevalence. Questionnaires describing the health history of the herd, management practices, and design of the swine facilities were obtained from the owners of 142 quarantined herds. Blood was collected from 29 finishing pigs over the age of 4 months, up to 29 adult females, and all herd boars. Factors considered to be significant in a bivariate analysis were combined in a stepwise multiple logistic regression analysis. The prevalence of prv-seropositive adults in each herd was bimodally distributed among the 142 herds. In 42 (30%) of the herds, none of the females tested was seropositive, which represented the lower mode. At least 90% of the adults tested were seropositive in 30 (21%) of the herds and represented the higher mode. The odds of the breeding swine of a given herd having a prv seroprevalence of ≥ 20% as compared with having a seroprevalence of < 20% was 1.654 times higher per 50 adults in the herd, 13.550 times higher if the finishing pigs were seropositive, 2.378 times higher if sows were housed inside during gestation, and 1.481 times lower per number of years since the imposition of quarantine. These findings indicate that a large proportion of quarantined herds may have a low seroprevalence of prv, making them prime candidates for test and removal. Pseudorabies virus might also be eliminated from these low-prevalence herds by a method referred to as management/vaccination, which is described. These methods are inexpensive, compared with offspring segregation or depopulation/repopulation, and represent a substantial cost savings for the swine industry.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the neurologic effects of reduced intake of phenylalanine and tyrosine in black-haired cats.

Animals—53 specific pathogen-free black domestic shorthair cats.

Procedure—Cats were fed purified diets containing various concentrations of phenylalanine and tyrosine for ≤ 9 months. Blood samples were obtained every 2 months for evaluation of serum aromatic amino acid concentrations. Cats were monitored for changes in hair color and neurologic or behavioral abnormalities. Three cats with neurologic deficits underwent clinical and electrophysiologic investigation; muscle and nerve biopsy specimens were also obtained from these cats.

Results—After 6 months, neurologic and behavioral abnormalities including vocalization and abnormal posture and gait were observed in cats that had received diets containing < 16 g of total aromatic amino acid/kg of diet. Electrophysiologic data and results of microscopic examination of muscle and nerve biopsy specimens from 3 cats with neurologic signs were consistent with sensory neuropathy with primary axonal degeneration. Changes in hair color were detected in cats from all groups receiving < 16 g of phenylalanine plus tyrosine/kg of diet.

Conclusions and Clinical Relevance—Findings suggested that chronic dietary restriction of phenylalanine and tyrosine in cats may result in a predominantly sensory neuropathy. In cats, the long-term nutritional requirement for phenylalanine and tyrosine appears to be greater for normal neurologic function than that required in short-term growth experiments. Official present-day recommendations for dietary phenylalanine and tyrosine in cats may be insufficient to support normal long-term neurologic function. ( Am J Vet Res 2004;65:671–680)

Full access
in American Journal of Veterinary Research

SUMMARY

Leukocytosis (34,600 wbc/μl of blood) was detected in an apparently healthy 7-day-old Holstein heifer. Analysis of blood samples obtained over the next 41 days revealed chronic progressive neutrophilia, which peaked at > 85% neutrophils and exceeded 100,000 wbc/μl. In vitro assessment of isolated blood neutrophils obtained from the heifer at 38 and 45 days of age revealed selected functional abnormalities. Endocytosis of immunoglobulin-opsonized Staphylococcus aureus and killing of this test organism by the calf’s neutrophils were significantly diminished, as were phagocytosis-associated superoxide generation, chemiluminescence activity, and myeloperoxidase-catalyzed iodination. Diminished H2O2 elaboration by the calf’s neutrophils was evident during ingestion of opsonized zymosan or on exposure to phorbol myristate acetate. Extracellular release (secretion) of elastase during ingestion of zymosan was also diminished, although total cell content of elastase was normal, compared with that of neutrophils from age-matched calves, and granular or other morphologic abnormalities of the calf’s neutrophils were not evident by ultrastructural examination. Abnormalities of random migration were inconsistently detected, and normal or high degree of antibody-dependent cytotoxicity or natural killing by the calf’s neutrophils was observed. Similar in vitro assessment of neutrophils obtained from the calf’s dam revealed no functional abnormalities. The calf died at 48 days of age, with persistent fever and chronic diarrhea, despite administration of antibiotics. Histologic examination at necropsy revealed large numbers of intravascular neutrophils in most tissues, including massive neutrophil sequestration in spleen. However, a striking lack of extravascular neutrophils was evident in inflamed submucosa adjacent to intestinal ulcers heavily contaminated with enteric microorganisms. Bone marrow examination revealed diffuse myeloid hyperplasia, but no other abnormalities.

The clinical and pathologic features in this calf were similar to those in previously reported human patients or Irish Setters with genetic deficiency of the CD11/CD18 leukocyte glycoprotein complex, thus prompting further postmortem evaluations. Results of immunoblot analyses of the neutrophil lysates of the heifer calf (isolated and stored prior to death) documented severe deficiency of Mac-1 (CD11b/CD18). Results of immunofluorescent analyses indicated substantially diminished (intermediate) amounts ofthe Mac-1 β subunit (CD18) on blood neutrophils of the calf's dam and sire and on neutrophils of 8 of 15 paternal half-siblings; findings were consistent with an autosomal recessive trait in the proband's kindred. Findings also indicate that genetic abnormalities of CD11/CD18 proteins may underlie the molecular pathogenesis of disease in this calf as well as other previously described examples of the granulocytopathy syndrome in Holstein cattle.

Free access
in American Journal of Veterinary Research