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  • Author or Editor: Brian J. McCluskey x
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In February 2004, an HPAI virus was confirmed to have infected a flock of broiler chickens in Gonzales County, Texas. Subsequent epidemiologic investigation identified infected birds in 2 live-bird markets in the area of Houston, Tex; these markets had received birds from the index flock or birds that had been transported by the index flock manager. All infected premises were depopulated, cleaned, and disinfected. Disease surveillance standards were established to assess the potential for spread of this virus from the index flock. Surveillance testing in commercial and noncommercial poultry operations revealed no area spread of virus from the index flock.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine risk factors associated with hemorrhagic bowel syndrome (HBS) among dairy cattle in the United States and identify characteristics of HBS in individual cows.

Design—Cross-sectional, population-based survey.

Sample Population—A stratified random sample of 1,013 dairy operations with ≥ 30 cows located in 21 states.

Procedure—Information on management and animal health-related topics was collected with a questionnaire.

Results—HBS was estimated to have been observed on 9.1% of operations during the preceding 5 years and on 5.1% of operations during the preceding 12 months. Factors found in multivariable analysis to be associated with the occurrence of HBS during the preceding 12 months were large herd size, administration of bovine somatotropin, and routine use of milk urea nitrogen concentration to determine ration composition. Use of pasture as part of the lactating cow ration during the growing season was associated with decreased odds of HBS in operations with rolling herd average milk production ≤ 20,000 lb, whereas in operations with higher milk production, use of pasture was not associated with occurrence of HBS. For individual cows with signs consistent with HBS, the third lactation was the median of the parity distribution and the median time between parturition and the onset of clinical signs was 104 days.

Conclusions and Clinical Relevance—Results suggest that management practices implemented to achieve high milk production may increase the risk of developing HBS in dairy cattle. Increased consumption of a high-energy diet seems to be the most plausible common pathway for all of the risk factors that have been described. (J Am Vet Med Assoc 2005;226:1700–1706)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine effects on production and risk of removal related to Mycobacterium avium subsp paratuberculosis (MAP) infection at the individual animal level in dairy cattle.

Design—Longitudinal study.

Animals—7,879 dairy cows from 38 herds in 16 states.

Procedure—A subset of dairy cattle operations that participated in the National Animal Health Monitoring System Dairy 2002 study was evaluated via a serum ELISA for antibodies against MAP and categorized according to ELISA score. Dairy Herd Improvement Association records were obtained to collect current and historical lactation data and removal (ie, culling) information. Production variables were evaluated on the basis of serum ELISA category.

Results—Cows with strong positive results had mature equivalent (ME) 305-day milk production, ME 305-day maximum milk production, and total lifetime milk production that were significantly lower than cows in other categories. No differences were observed for ME 305-day fat and protein percentages, age, lactation, and lactation mean linear somatic cell count score between cows with strong positive results and those with negative results. After accounting for lactation number and relative herd-level milk production, cows with strong positive results were significantly more likely to have been removed by 1 year after testing.

Conclusions and Clinical Relevance—Without management changes designed to reduce the farm-level prevalence of MAP infection, paratuberculosis will continue to reduce farm income by decreasing milk production and potentially increasing premature removal from the herd. (J Am Vet Med Assoc 2005;227:1975–1981)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To report clinical and serologic findings in horses with oral vesicular lesions that were consistent with vesicular stomatitis (VS) but apparently were not associated with VS virus (VSV) infection.

Design—Serial case study.

Animals—8 horses.

Procedure—Horses were quarantined after appearance of oral lesions typical of VS. Severity of clinical signs was scored every 2 to 5 days for 3 months. Serum samples were tested for antibodies by use of competitive ELISA (cELISA), capture ELISA for IgM, serum neutralization, and complement fixation (CF). Virus isolation was attempted from swab specimens of active lesions.

Results—2 horses with oral vesicular lesions on day 1 had antibodies (cELISA and CF) against VSV; however, results of CF were negative by day 19. Five of the 6 remaining horses were seronegative but developed oral lesions by day 23. Virus isolation was unsuccessful for all horses.

Conclusion and Clinical Relevance—Horses were quarantined for 75 days in compliance with state and federal regulations. However, evidence suggests that oral lesions were apparently not associated with VSV infection. The occurrence in livestock of a vesicular disease that is not caused by VSV could confound efforts to improve control of VS in the United States and could impact foreign trade.Vesicular stomatitis is of substantial economic and regulatory concern. (J Am Vet Med Assoc 2000;216:1399–1404)

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in Journal of the American Veterinary Medical Association

The US dairy industry is moving toward fewer dairy farms with more cattle per farm. Between 1995 and 2005, the number of dairy farms decreased by 43.9% (from 139,670 to 78,295), but the total number of milk cows decreased by only 4.5% (from 9.47 to 9.04 million). 1 Consequently, the average herd size for dairies in the United States has almost doubled during the past 10 years.

It has become difficult for dairy farms to be completely self-sufficient, self-contained production units. Large dairy farms are at risk of exposure to disease agents from external sources of labor, feedstuffs, replacement

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in Journal of the American Veterinary Medical Association