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Summary

The role of platelet-activating factor (paf) in mediating the colonic damage that develops after large-colon torsion was studied in 14 ponies. Morphologic changes in areas of the ascending colon and selected abdominal and thoracic viscera after 1 hour of large-colon torsion and 3 to 5 hours of reperfusion were determined, as well as the protective effects of systemic administration of a specific paf antagonist (WEB 2086). Ponies were selected then allocated at random and in equal numbers to 2 groups that received 1 of 2 treatments prior to induction of large-colon torsion: group 1 —control (saline solution), and group 2 — WEB 2086 (3 mg/kg of body weight loading dose and 3 mg/kg/h for the remainder of the study). In each pony, full-thickness tissue specimens from the gastrointestinal tract —cecum, pelvic flexure, left and right ventral colon, and right dorsal colon —heart, left lung, liver, left adrenal gland, spleen, and right kidney were collected and histologically evaluated. Edema, mucosal necrosis, and neutrophil infiltration in colonic sections were graded from 0 (normal) to 3 (most severe changes). Sections of liver and lung from 3 ponies in each group, and colon from 1 pony in each group, also were examined by transmission electron microscopy to determine the presence of ultrastructural alterations.

Ischemia and reperfusion induced marked changes in all sections of colon in all ponies: moderate to severe submucosal edema, moderate necrosis of the superficial epithelium and lamina propria, and necrosis of the mucosal crypt epithelium. Extra-vascular neutrophil accumulation was evident in all sections of colon and cecum, but not in other tissues. Ultrastructural lesions were not present in hepato-cytes or pneumocytes, or in the endothelial cells of liver, lung, and colon. Bacteria were observed by electron microscopy in 5% of hepatic sinusoids. Administration of a specific paf antagonist, WEB 2086, failed to reduce severity of the observed lesions, indicating that it was not cytoprotective at the dosage used in this model of ischemia-reperfusion injury.

Free access
in American Journal of Veterinary Research

SUMMARY

Large colon torsion frequently is a fatal condition in horses. The purpose of the study reported here was to determine systemic arterial pressure, plasma eicosanoid concentrations, colonic blood flow, vascular resistance, tissue pH, and morphologic features associated with large colon torsion and detorsion, and to evaluate the effects of sodium heparin (80 IU/kg of body weight, iv) treatment on these values. Values were determined in 20 anesthetized ponies that were randomly assigned into 4 equal groups: control; control/heparin; torsion; torsion/heparin. Torsions were created by a 720° rotation of the cecum and colon around their long axes at the sternal and diaphragmatic flexures. After 1 hour of torsion, the torsion was corrected and the colon was allowed to reperfuse for 1 hour. Heparin was administered 30 minutes into the experiment. Parametric data were analyzed (P ≤ 0.05), using split-plot analysis of variance, with differences between means evaluated with a modified Bonferroni t test; histopathologic data were analyzed (P ≤ 0.05) with a Kruskal-Wallis one-way analysis of variance by ranks. Heparin prevented colonic detorsion-induced hypotension and increases in vascular resistance and thromboxane concentration, and it significantly increased colonic blood flow for 40 minutes during reperfusion. Heparin did not alter prostacyclin concentration or the histologic appearance of the large colon.

Free access
in American Journal of Veterinary Research

Summary:

Eight of 19 calves born to bovine viral diarrhea virus (bvdv)-negative and -immunocompetent dams were determined to be infected with a noncytopathic strain of bvdv. Six of the 8 calves had diarrhea and 2 had no clinical signs of disease. In 3 euthanatized calves, lesions consistent with mucosal disease were found throughout the gastrointestinal tract, and the virus was isolated from the spleen, lymph nodes, and small intestine. In 5 calves, bvdv was isolated from mononuclear cells in blood samples obtained 21 days apart, indicating persistent infection. The virus was not isolated from sera obtained from 2 calves, with chronic nonclinical infections, that had neutralizing antibody titers ≥ 1:512 against bovine viral diarrhea-Singer virus and titers ≥ 1:256 against the persistent bvdv. Twenty-one days after vaccination with a vaccine that contained inactivated noncytopathic and cytopathic biotypes of bvdv, 4 of 5 persistently infected calves had neutralizing antibody titers ≤ 1:4 against the bovine viral diarrhea-Singer virus and their persistent virus. Prior to vaccination, 2 of 11 virus-negative calves had neutralizing antibody titers ≤ 1:128 against the bovine viral diarrhea-Singer virus, and after vaccination, only 1 virus-negative calf had a titer ≤ 1:512. At 149 days after revaccination and prior to weaning, 4 virus-negative calves had neutralizing antibody titers ≤ 1:512 (range, 1:16 to 1:384). Under the specific conditions in this herd, we were not able to detect a beneficial effect of vaccination. Colostral origin bvdv-specific antibody, capable of neutralizing the persistently infective bvdv strain, most likely interfered with isolation of the virus from the sera of 2 persistently infected calves.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate the sensitivity and specificity of an enzyme immunoassay (EIA) for antibodies to a recombinant Blastomyces adhesin-1 repeat antigen (rBAD-1) to aid in the diagnosis of blastomycosis in dogs and compare the findings with results from other tests used for this purpose.

Design—Prospective analytic study.

Sample—Serum and urine from 70 dogs with and without blastomycosis.

Procedures—Serum and urine samples were collected from dogs with blastomycosis (n = 21), histoplasmosis (8), or nonfungal pulmonary disease (21) and from healthy control dogs living in a blastomycosis-endemic area (20). Serum was tested for antibodies against Blastomyces dermatitidis with the rBAD-1 antibody EIA and an A-antigen antibody agar gel immunodiffusion (AGID) assay. Serum and urine were tested for B dermatitidis antigen with a quantitative EIA.

Results—Sensitivity of the quantitative antigen EIA was 100% in serum and urine samples from dogs with blastomycosis, with specificity of 95% in urine samples from dogs with nonfungal pulmonary disease and 100% in urine samples from healthy dogs. Sensitivity of the rBAD-1 antibody EIA (95%) was significantly greater than that of the A-antigen antibody AGID assay (65%). Specificity of the antibody EIA was 88% in dogs with histoplasmosis, 95% in healthy dogs, and 100% in dogs with nonfungal pulmonary disease.

Conclusions and Clinical Relevance—The rBAD-1 antibody EIA had greater sensitivity than the A-antigen antibody AGID assay in dogs with blastomycosis. This antibody EIA may assist in distinguishing histoplasmosis from blastomycosis. Further evaluation in a larger prospective study is needed to verify these results.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether daily administration of pyrantel tartrate can prevent infection in horses experimentally challenged with Sarcocystis neurona.

Animals—24 mixed-breed specific-pathogen-free weanling horses, 10 adult horses, 1 opossum, and 6 mice.

ProcedureSarcocystis neurona-naïve weanling horses were randomly allocated to 2 groups. Group A received pyrantel tartrate at the labeled dose, and group B received a nonmedicated pellet. Both groups were orally inoculated with 100 sporocysts/d for 28 days, 500 sporocysts/d for 28 days, and 1,000 sporocysts/ d for 56 days. Blood samples were collected weekly, and CSF was collected monthly. Ten seronegative adult horses were monitored as untreated, uninfected control animals. All serum and CSF samples were tested by use of western blot tests to detect antibodies against S neurona. At the end of the study, the number of seropositive and CSF-positive horses in groups A and B were compared by use of the Fisher exact test. Time to seroconversion on the basis of treatment groups and sex of horses was compared in 2 univariable Cox proportional hazards models.

Results—After 134 days of sporocyst inoculation, no significant differences were found between groups A and B for results of western blot tests of serum or CSF. There were no significant differences in number of days to seroconversion on the basis of treatment groups or sex of horses. The control horses remained seronegative.

Conclusions and Clinical Relevance—Daily administration of pyrantel tartrate at the current labeled dose does not prevent S neurona infection in horses. (Am J Vet Res 2005;66:846–852)

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

The aim of this study was to investigate whether plasma neurofilament light chain (pNfL) concentration was altered in Labrador Retrievers with idiopathic laryngeal paralysis (ILP) compared to a control population. A secondary aim was to investigate relationships between age, height, weight, and body mass index in the populations studied.

ANIMALS

123 dogs: 62 purebred Labrador Retrievers with ILP (ILP Cases) and 61 age-matched healthy medium- to large-breed dogs (Controls).

METHODS

Dogs, recruited from August 1, 2016, to March 1, 2022, were categorized as case or control based on a combination of physical exam, neurologic exam, and history. Blood plasma was collected, and pNfL concentration was measured. pNfL concentrations were compared between ILP Cases and Controls. Covariables including age, height, and weight were collected. Relationships between pNfL and covariables were analyzed within and between groups. In dogs where 2 plasma samples were available from differing time points, pNfL concentrations were measured to evaluate alterations over time.

RESULTS

No significant difference in pNfL concentration was found between ILP Cases and Control (P = .36). pNfL concentrations had moderate negative correlations with weight and height in the Control group; other variables did not correlate with pNfL concentrations in ILP Case or Control groups. pNfL concentrations do not correlate with ILP disease status or duration in Labrador Retrievers.

CLINICAL RELEVANCE

There is no evidence that pNfL levels are altered due to ILP disease duration or progression when compared with healthy controls. When evaluating pNfL concentrations in the dog, weight and height should be considered.

Open access
in American Journal of Veterinary Research