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Abstract

Objective

To determine prevalence of paratuberculosis among dairy cattle herds and to identify associated soil-related risk factors.

Sample Population

Serum and soil samples for 121 Michigan dairy herds.

Procedure

Blood samples were collected from cows at each farm and tested for Mycobacterium paratuberculosis, using an antibody ELISA. Soil samples were collected from pastures and exercise lots; pH and available iron content were determined. A questionnaire was administered to collect data regarding farm management practices and productivity.

Results

55% of the herds tested had ≥ 2 M paratuberculosis-positive cattle. Adjusting sample prevalence for distribution of herd size strata yielded a statewide herd prevalence of 54%. Of 3,886 cattle tested, 267 had positive results. Prevalence of test-positive cattle was 6.9%. For every part per million (ppm) increase in soil iron content, there was a 1.4% increase in the risk of a herd being test-positive. An increase in soil pH of 0.1 was associated with a 5% decrease and an increase in soil iron content of 10 ppm was associated with a 4% increase in the number of test-positive cattle. Application of lime to pasture areas was associated with a herd being only 10% as likely to be paratuberculosis positive and with a 72% reduction in number of test-positive cattle.

Conclusions and Clinical Relevance

Prevalence of paratuberculosis-positive dairy herds in Michigan (54%) was greater than expected, but prevalence of paratuberculosis-positive cattle (6.9%) was within anticipated values. These prevalences were associated positively with acidic soil and increased soil iron content. Application of lime to pasture areas was associated with reduced risk of paratuberculosis. (Am J Vet Res 1999;60:589–596)

Free access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association

Objective

To perform a herd-level analysis of economic losses associated with paratuberculosis in dairy herds.

Design

Cross-sectional study.

Sample Population

A multistage stratified random sample of 121 dairy herds in Michigan.

Procedure

A 2-part questionnaire was used to gather data on management practices, herd productivity, labor use, and expenditures. Blood samples were collected from a random sample of cows ≥ 2 years old in each herd and tested for antibodies to Mycobacterium paratuberculosis. A herd was considered negative for paratuberculosis if results for all cows tested were negative. Multivariable linear regression was used to evaluate the data.

Results

A 10% increase in proportion of cows positive for paratuberculosis was associated with a 33.4 kg (73.5 Ib) decrease in mean weight of culled cows. Mortality rate among herds positive for paratuberculosis was 3% higher than rate among herds negative for paratuberculosis. Herds positive for paratuberculosis did not have a significantly higher annual number of hours of labor per cow than did herds negative for paratuberculosis.

Clinical Implications

For a herd of average size and cull rate, the reduction in mean weight of culled cows attributable to paratuberculosis represented a loss of approximately $1,150 annually for each 10% increase in herd prevalence of paratuberculosis. The increased mortality rate attributable to paratuberculosis represented a loss of between $1,607 and $4,400 on the basis of lost slaughter value and cost of replacement heifers. (J Am Vet Med Assoc 1999;214:822–825)

Free access
in Journal of the American Veterinary Medical Association

Objectives

To determine attitudes of veterinarians, animal control directors, and county prosecutors in Michigan toward enforcement of state animal cruelty legislation and to identify factors associated with whether veterinarians would report suspected cases of animal cruelty.

Design

Survey.

Sample Population

Questionnaires were sent to 1,146 Michigan Veterinary Medical Association member veterinarians, 139 animal control directors, and 83 county prosecutors in Michigan.

Results

740 (65%) veterinarians, 70 (50%) animal control directors, and 43 (52%) prosecutors responded. Six hundred forty six of 735 (88%) veterinarians reported having treated an animal that they believed had been a victim of animal cruelty, but only 192 of 719 (27%) had ever reported a case of animal cruelty, and only 217 of 734 (30%) had ever testified in an animal cruelty case. Logistic regression analysis of responses revealed that the only factor associated with whether veterinarians would report cases of suspected animal cruelty was the potential reactions of the involved clients to the accusation of animal cruelty. Veterinarians who rated reaction of the involved client as important, very important, or essential to their decision whether to report a case of animal cruelty were less likely to report such cases than were veterinarians who rated potential client reaction as somewhat important or unimportant.

Clinical Implications

Concern about potential client reaction was the most important factor in whether veterinarians would report cases of suspected animal cruelty. (J Am Vet Med Assoc 1997;211:1521–1523)

Free access
in Journal of the American Veterinary Medical Association