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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
in Journal of the American Veterinary Medical Association

Objective

To identify management factors affecting the risk of animals developing vesicular stomatitis (VS).

Design

Case-control study.

Animals

Horses, cattle, and sheep with suspected vesicular stomatitis on 395 premises in Colorado, New Mexico, Utah, and Arizona.

Procedure

Data were collected during the VS outbreak of 1997. Diagnosticians interviewed livestock owners and completed a supplemental questionnaire. Cases were defined as those premises that had a completed questionnaire and had ≥ 1 animal positive for VS. Control premises were all premises investigated that had a completed questionnaire and on which the animals had been tested but VS was not detected.

Results

Animals that had access to a shelter or barn had a reduced risk of developing VS (OR, 0.6; 95% confidence interval [CI], 0.35 to 0.99). This effect was more pronounced for equine premises (OR, 0.5; 95% CI, 0.3 to 0.9). Conversely, during an adjusted analysis on equine premises, risk of developing disease was increased slightly where animals had access to pasture (OR, 2.01; 95% CI, 1.1 to 3.7). On all premises where owners reported insect populations were greater than normal, odds of developing disease were significantly increased (OR, 2.5; 95% CI, 1.47 to 4.47). Premises with animals housed < 0.25 miles from running water were more than twice as likely to have clinical signs of VS (OR, 2.6; 95% CI, 1.32 to 5.0).

Conclusions and Clinical Relevance

These results support reports of others that suggest biting insects are a vector in VS virus transmission. Management practices to reduce exposure to biting insects might reduce the risk of VS. (J Am Vet Med Assoc 1999;215:1263–1268)

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in Journal of the American Veterinary Medical Association

Objective

To determine financial impact of an outbreak of vesicular stomatitis in the San Luis Valley of southern Colorado.

Design

Survey and financial analysis.

Sample Population

16 ranchers whose beef herds were affected by the 1995 outbreak.

Procedure

Information concerning financial effects during the outbreak year was collected by personal interview of each rancher and examination of financial records.

Results

Affected herds ranged from 79 to 956 cows (mean, 345). Cow case-fatality rates ranged from 0 to 80%, with calf case-fatality rates ranging from 0 to 28% and overall case-fatality rates of 0 to 15%. Median financial loss was $7,818/ranch and mean financial loss was $15,565/ranch, excluding total financial losses associated with sale of calves. Primary financial losses for these beef herds were attributed to increased culling rates, death of pregnant cows, loss of income from calves, and costs for additional labor during the outbreak. Some costs were attributable to a decrease in market price for beef and a drought during the year after the outbreak.

Clinical Implications

Financial losses for an out-break of vesicular stomatitis can be attributed to effects of the disease and costs associated with imposed quarantines. (J Am Vet Med Assoc 1998; 212:820-823)

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in Journal of the American Veterinary Medical Association

Objective

To determine potential risk factors for vesicular stomatitis (VS) in Colorado livestock in 1995 and evaluate VS virus (VSV) exposure of Colorado livestock in 1996.

Design

Retrospective case-control study of VS risk factors and seroprevalence evaluation.

Sample Population

Premises included 52 that had VS-positive animals and 33 that did not have VS-positive animals during the 1995 epidemic, and 8 in the vicinity of premises that had VS-positive animals during the 1995 epidemic.

Procedure

Layout and management data for premises were collected during site visits in 1996. Signalment and management data were collected for animals from which samples were obtained, and samples were tested by serologic examination and virus isolation. The VSV seroprevalence rate was estimated for Colorado, using serum obtained for equine infectious anemia testing and from the Market Cattle Identification program in Colorado.

Results

At least 1 animal was seropositive for VSV. on 35 of 52 (67%) premises, and 71 of 228 (31 %) animals tested were seropositive for VSV Seroprevalence was 63 of 170 (37%) for horses and 8 of 54 (15%) for cattle. Seroprevalence of VSV in animals from nonstudy premises in Colorado in 1996 was estimated to be 1.1% in cattle and 0.8% in horses.

Clinical Implications

Overall VSV seroprevalence in Colorado livestock was less than seroprevalence in epidemic areas, and seroprevalence rates in epidemic areas were greater for horses than cattle. Results may indicate that some animals had subclinical VSV infection during epidemics and that animals may be exposed to VSV between epidemics. (J Am Vet Med Assoc 1998;213:1265-1269)

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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)

Full access
in Journal of the American Veterinary Medical Association