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  • Author or Editor: R. P. Ellis x
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Abstract

Objective—To determine whether immunity against bovine respiratory syncytial virus (BRSV) mitigates the effects of 3-methylindole (3MI) on occurrence of bovine respiratory tract disease (BRD) and rate of gain in feedlot cattle.

Animals—254 mixed-breed beef cattle.

Procedure—Cattle were randomly assigned to 1 of 3 groups at the time of arrival at the feedlot. One group was vaccinated with an inactivated BRSV vaccine, another was vaccinated with a modified-live BRSV vaccine, and the third was maintained as unvaccinated control cattle. On days 0 and 28, serum BRSV antibody concentrations were measured, using serum neutralizing and ELISA techniques. Serum 3MI concentrations were measured at feedlot arrival and 3 days later. Cattle were monitored for development of BRD. At slaughter, lungs were evaluated grossly for chronic lesions.

Results—Higher serum 3MI concentrations early in the feeding period were associated with lower mean daily gain. Control cattle were more likely to be treated for BRD after day 3, compared with cattle vaccinated with the modified-live BRSV vaccine. Humoral immunity against BRSV did not appear to modify the effect of 3MI on development of BRD or mean daily gain.

Conclusions and Clinical Relevance—Results suggest that abrogating the effects of 3MI and BRSV infection may improve the health and growth performance of feedlot cattle. However, in this study, immunity against BRSV did not appear to protect against the potential synergism between 3MI and BRSV infection, possibly because of the slow rates of gain of cattle included in the study or timing of sample collection. (Am J Vet Res 2000;61:1309–1314)

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in American Journal of Veterinary Research

Abstract

Objective—To compare the frequency of isolation, genotypes, and in vivo production of major lethal toxins of Clostridium perfringens in adult dairy cows affected with hemorrhagic bowel syndrome (HBS) versus left-displaced abomasum (LDA).

Design—Case-control study.

Animals—10 adult dairy cattle with HBS (cases) and 10 adult dairy cattle with LDA matched with cases by herd of origin (controls).

Procedure—Samples of gastrointestinal contents were obtained from multiple sites during surgery or necropsy examination. Each sample underwent testing for anaerobic bacteria by use of 3 culture methods. The genotype of isolates of C perfringens was determined via multiplex polymerase chain reaction assay. Major lethal toxins were detected by use of an ELISA. Data were analyzed with multivariable logistic regression and X2 analysis.

ResultsC perfringens type A and type A with the beta2 gene (A + beta2) were the only genotypes isolated. Isolation of C perfringens type A and type A + beta2 was 6.56 and 3.3 times as likely, respectively, to occur in samples from cattle with HBS than in cattle with LDA. Alpha toxin was detected in 7 of 36 samples from cases and in 0 of 32 samples from controls. Beta2 toxin was detected in 9 of 36 samples from cases and 0 of 36 samples from controls.

Conclusions and Clinical RelevanceC perfringens type A and type A + beta2 can be isolated from the gastrointestinal tract with significantly greater odds in cattle with HBS than in herdmates with LDA. Alpha and beta2 toxins were detected in samples from cows with HBS but not from cows with LDA. (J Am Vet Med Assoc 2005;227:132–138)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether a combination viral vaccine containing a modified-live bovine herpesvirus-1 (BHV-1) would protect calves from infection with virulent field strains of BHV-1 for weeks or months after vaccination.

Design—Randomized controlled trial, performed in 2 replicates.

Animals—63 weaned 4- to 6-month-old crossbred beef calves seronegative for antibody against BHV-1.

Procedures—Calves were randomly allocated to 1 of 2 treatment groups. Control calves (n = 10/replicate) received a combination modified-live mixed viral vaccine without BHV-1, and treatment calves (20 and 23/replicate) received a combination modified-live mixed viral vaccine containing BHV-1. Each group was challenged via aerosol with 1 of 2 field strains of BHV-1, 30 days after vaccination in replicate 1 and 97 days after vaccination in replicate 2. After challenge, calves were commingled in 1 drylot pen. Clinical signs, immune responses, and nasal shedding of virus were monitored for 10 days after challenge, after which the calves were euthanatized and tracheal lesions were assessed.

Results—Vaccination stimulated production of BHV-1–specific IgG antibody that cross-neutralized several field and laboratory strains of BHV-1. Challenge with both field strains of BHV-1 resulted in moderate to severe respiratory tract disease in control calves. Treatment calves had significantly fewer signs of clinical disease, shed less BHV-1, had less or no weight loss after challenge, and had fewer tracheal lesions than control calves for at least 97 days after vaccination.

Conclusions and Clinical Relevance—Administration of the combination modified-live BHV-1 vaccine yielded significant disease-sparing effects in calves experimentally infected with virulent field strains of BHV-1.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the percentage of broodmares and foals that shed Clostridium perfringens in their feces and classify the genotypes of those isolates.

Design—Prospective cross-sectional study.

Animals—128 broodmares and their foals on 6 equine premises.

Procedures—Anaerobic and aerobic bacteriologic cultures were performed on feces collected 3 times from broodmares and foals. All isolates of C perfringens were genotyped.

ResultsClostridium perfringens was isolated from the feces of 90% of 3-day-old foals and 64% of foals at 8 to 12 hours of age. A lower percentage of broodmares and 1- to 2-month-old foals shed C perfringens in their feces, compared with neonatal foals. Among samples with positive results, C perfringens type A was the most common genotype identified (85%); C perfringens type A with the β2 toxin gene was identified in 12% of samples, C perfringens type A with the enterotoxin gene was identified in 2.1% of samples, and C perfringens type C was identified in < 1% of samples.

Conclusions and Clinical RelevanceClostridium perfringens was identified from the feces of all but 6 foals by 3 days of age and is likely part of the normal microflora of neonatal foals. Most isolates from broodmares and foals are C perfringens type A; thus, the clinical relevance of culture results alone is questionable. Clostridium perfringens type C, which has been associated with neonatal enterocolitis, is rarely found in the feces of horses. (J Am Vet Med Assoc 2002;220:342–348)

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in Journal of the American Veterinary Medical Association