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in Journal of the American Veterinary Medical Association

Summary

An ELISA, using purified flagellin of Borrelia burgdorferi as the solid-phase antigen, was used to measure antibody concentrations to B burgdorferi in dairy cattle in Wisconsin. Serum obtained from 5,060 cows in 160 randomly selected herds in the state were tested. Serum from an additional 2,600 cattle in Barron County, Wis, a county with a high annual incidence of B burgdorferi infections in human beings, was also tested. Only 7% of the cows that were tested, but 66% of the herds that were tested, were seropositive for B burgdorferi. Sixteen percent of the herds had a prevalence of ≥ 15% seropositive cows, whereas 50% of the herds had a prevalence of 1 to 14% seropositive cows. Seropositive herds were concentrated in the west-central part of Wisconsin. An association existed between the geographic location of seropositive herds and counties in which B burgdorferi infection of human beings was acquired (P< 0.05) as well as the geographic location of seropositive herds and the geographic distribution of Ixodes scapularis (P < 0.05). Barron County, in which B burgdorferi infection is endemic, had a significantly (P< 0.05) higher percentage of seropositive cows (17%) than did the state of Wisconsin (7%).

Free access
in American Journal of Veterinary Research

Summary

An elisa was developed to detect antibodies to the 41-kd flagellin (P41) of Borrelia burgdorferi in serum obtained from cattle. Absorption studies, immunoblot analysis, immunoelectron microscopy, and correlation of results of the P41 -elisa and the P39- elisa as well as measurement of the antibody to P41 in calves challenge-exposed with Borrelia theileri were used to assess the specificity of the P41-elisa. Antigens derived from Escherichia coli, Leptospira interrogans serovar hardjo, and B burgdorferi were used for absorption studies and immunoblot analysis. Antibodies to P41 of B burgdorferi cross-reacted with antigens of E coli, but were not cross-reactive with L hardjo. A value 3 SD higher than the mean of the negative-control population of cattle was defined as the minimum value (cutoff value) for a positive result by the P41-elisa. Use of this value for classification of test results reduced the predicted rate of false-positive results attributable to E coli cross-reactivity to 1%. Immunoblot analysis revealed that test-positive serum from cattle reacted mainly with 41-, 39-, 34-, and 31-kd proteins of B burgdorferi, as well as several smaller proteins. Immunoelectron microscopy revealed that serum from cattle that was test-positive by the P41-elisa bound to the flagellin and outer membrane of B burgdorferi. Results of absorption studies, immunoblot analysis, and immunoelectron microscopy were correlated and indicated that serum from cattle that was test-positive by P41-elisa had stronger reactivity to B burgdorferi antigens than to antigens of E coli or L hardjo. The concentrations of antibodies measured by P41-elisa and P39-elisa testing were highly correlated (R2 = 0.78). Calves challenge-exposed with B theileri also had test-positive results by the P41-elisa as early as 2 weeks after exposure, but serum antibody concentrations decreased to prechallenge-exposure concentrations by 9 weeks after exposure. We concluded that the P41- elisa was useful as a screening method to detect B burgdorferi infections in cattle.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To compare serum total protein (sTP) and serum IgG (sIgG) concentrations In neonatal calves administered colostrum or a bovine serum-based colostrum replacement (CR) product followed by a bovine serum-based colostrum supplement (CS) product.

Design—Randomized controlled clinical trial.

Animals—18 Jersey and 269 Holstein neonatal heifer calves.

Procedures—141 calves were given 4 L of colostrum in 1 or 2 feedings (first or only feeding was provided ≤ 2 hours after birth; when applicable, a second feeding was provided between 2 and 12 hours after birth). Other calves (n = 146) were fed 2 L of a CR product ≤ 2 hours after birth and then 2 L of a CS product between 2 and 12 hours after birth. Concentrations of sTP and sIgG were measured 1 to 7 days after birth. Data from cohorts on individual farms and for all farms were analyzed.

Results—Mean sTP and sIgG concentrations differed significantly between feeding groups. In calves fed colostrum and calves fed CR and CS products, mean ± SD sTP concentration was 5.58 ± 0.67 g/dL and 5.26 ± 0.54 g/dL, respectively, and mean sIgG concentration was 1,868 ± 854 mg/dL and 1,320 ± 620 mg/dL, respectively. The percentage of calves that had failure of passive transfer of immunity (ie, sIgG concentrations < 1,000 mg/dL) was not significantly different between groups.

Conclusions and Clinical Relevance—Results suggested that sequential feeding of bovine serum-based CR and CS products to neonatal calves is an alternative to feeding colostrum for achieving passive transfer of immunity.

Full access
in Journal of the American Veterinary Medical Association

Objective

To determine associations between subclinical Mycobacterium paratuberculosis infection and milk production, milk components, and somatic cell counts of dairy cattle.

Design

Cross-sectional epidemiologic survey.

Animals

23 dairy herds in Wisconsin containing 1,653 adult cows were studied. The herds had above average milk production and a history of bovine paratuberculosis in the herd within the previous 12 months.

Procedure

All adult cows in the herds were tested for paratuberculosis by use of an absorbed ELISA. Milk yield, fat, protein, and somatic cell count data were retrieved electronically from Dairy Herd Improvement Association records.

Results

147 ELISA-positive and 1,506 ELISA-negative cows were identified. ELISA-positive cows had a mature-equivalent milk production of 376 kg (829 lb)/lactation less than that for ELISA-negative herdmates. Significant difference was not found in lactation average percentages of fat and protein, or somatic cell count linear score. When comparing ELISA-positive and -negative cow's current mature equivalent milk with all previous lactations, significant difference was found only from the immediate-preceding lactation. When this difference was examined by parity group, significant difference was confined to cows in the second lactation.

Clinical Implications

Subclinical paratuberculosis infections, as determined by ELISA, are associated with a 4% reduction in milk yield and add to the already substantial costs of clinical M paratuberculosis infection in the dairy industry. (J Am Vet Med Assoc 1996;208:1872-1876)

Free access
in Journal of the American Veterinary Medical Association

Summary

An antibiotic selected for surgical antimicrobial prophylaxis must be present in the surgical site throughout the operation in concentration sufficient to prevent growth of contaminating pathogens. The antimicrobial spectrum, minimal toxicity, and low cost of cefazolin make this first-generation cephalosporin a logical choice for antimicrobial prophylaxis in small animal surgical procedures in which the normal microbiologic flora of skin and gastrointestinal tract are the most likely pathogens. Pharmacokinetic variables of cefazolin were determined in serum and surgical wounds in dogs. Drug concentration in interstitial fluid of muscle biopsy specimens taken at random from wound surfaces and in postoperative wound fluid samples were determined. Effective surgical wound concentration of cefazolin was defined as 4 μg/ml, a concentration that inhibited the growth in vitro of 100% of staphylococcal and 80% of Escherichia coli clinical isolates. After iv and sc administrations, cefazolin equilibrated rapidly between serum and the surgical wound, and concentrations in the 2 sites decreased in parallel. With a bolus dose of 20 mg/kg of body weight given iv at the beginning of surgery and repeated by sc administration at 6 hours, cefazolin concentration in the surgical wound remained > 4 μg/ml for longer than 12 hours.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the seroprevalence of paratuberculosis by use of 2 commercial ELISAs in association with prevalence of fecal shedding of mycobacteria within beef cattle herds.

Design—Cross-sectional field study.

Animals—Six beef herds (affected herds; 522 cattle) with and 3 geographically matched herds (181 cattle) without high seroprevalence of paratuberculosis.

Procedures—Blood and fecal samples were collected from adult cattle and assessed for serum anti–Mycobacterium avium subsp paratuberculosis (MAP) antibodies with 2 commercial ELISA kits and submitted for bacterial culture for MAP and environmental bacteria (termed environmental mycobacteria) via a radiometric method, respectively. Species of mycobacterial isolates were identified, and sensitivities and specificities of the 2 ELISAs were compared.

Results—Compared with comparison cattle, cattle from affected herds were 9.4 times as likely to have environmental mycobacteria isolated from feces. Among the 6 affected and 3 comparison herds, the proportions of cattle shedding environmental mycobacteria were 0.225 (range, 0.1 to 0.72) and 0.04 (range, 0 to 0.06), respectively. Although relative MAP-detection specificities (compared with bacterial culture of feces) were different between the 2 ELISAs, sensitivities were not. Nine environmental mycobacterial species were iden-tified from participating herds. All affected herds apparently had ≥ 1 bovid infected with MAP, although MAP was not isolated from any cattle in comparison herds.

Conclusions and Clinical Relevance—In beef herds with persistently high rates of false-positive ELISA results, which may be associated with recovery of environmental myco-bacteria from feces, organism detection via bacterial culture of feces or PCR assay should direct paratuberculosis control measures.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate the effect of exposure to environmental mycobacteria on results of 2 commercial ELISAs for paratuberculosis in cattle.

Design—Experimental trial.

Animals—19 weaned crossbred beef calves.

Procedures—Calves were inoculated SC with 1 of 5 mycobacterial isolates (3 calves/isolate) derived from herds with high proportions of false-positive serologic reactions for paratuberculosis, Mycobacterium avium subsp paratuberculosis (MAP; positive control inoculum; 2 calves), or mineral oil (negative control inoculum; 2 calves). Sera were assessed at intervals by use of 2 ELISAs (A and B) for paratuberculosis in cattle, and all calves underwent tuberculosis testing at the end of the study.

Results—Neither mineral oil–inoculated calf had positive results with either ELISA during the study. Both MAP-inoculated calves were identified as seropositive via ELISA-A, and 1 calf was identified as seropositive via ELISA-B. By use of ELISA-A, ≥ 1 false-positive reaction over time was detected in 2, 3, 3, and 1 of the 3 calves injected with Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium scrofulaceum, or Mycobacterium terrae, respectively. By use of ELISA-B, only M scrofulaceum induced false-positive reactions (2/3 calves). Calves that had at least 1 positive ELISA-A result were more likely to be classified as suspect reactors via the caudal fold tuberculosis test.

Conclusions and Clinical Relevance—False-positive serologic reactions may occur during use of commercially available ELISAs for paratuberculosis in calves experimentally exposed to environmental mycobacteria; naturally occurring exposures with these mycobacteria may represent a cause for high proportions of false-positive serologic reactions for paratu-berculosis in some cattle herds.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objectives—To determine whether vaccination with a killed vaccine prevents fecal shedding of Mycobacterium avium subsp paratuberculosis, to compare effectiveness of a culture and cull program in vaccinated and nonvaccinated herds, and to compare paratuberculosis-related preventive management in vaccinated and nonvaccinated herds.

Sample Population—58 commercial Dutch dairy herds.

Design—Cross-sectional study (study A) in vaccinated (n = 25) and nonvaccinated (29) herds of dairy cows. Longitudinal study (study B) in vaccinated (n = 2) and nonvaccinated (2) herds of dairy cows.

Procedure—In study A, fecal samples were obtained from adult cows in herds with and without a history of vaccination with a killed vaccine. Management measures were evaluated. In study B, fecal samples were obtained 4 times at 6-month intervals from cows older than 6 months. Cows that had positive test results were removed from the herd directly after the outcome of the culture.

Results—In study A, differences were not detected among the 25 herds that were vaccinated; culture results were positive for M avium subsp paratuberculosis in 4.4% of herds. In 29 herds that had not been vaccinated, culture results were positive in 6.7%. In study B, the percentage of positive results on culture decreased from 10.9% and 5.7% to 3.5% and 0%, respectively in the 2 vaccinated herds. In the 2 nonvaccinated herds, percentages decreased from 6.1% and 16.5% to 0% and 2.3%, respectively. Management practices were different between herds that were vaccinated and herds that were not; owners of herds that were not vaccinated followed more preventive management procedures and practiced less feeding of raw milk to calves.

Conclusions and Clinical Relevance—Vaccination of calves with a killed vaccine does not prevent transmission of M avium subsp paratuberculosis; therefore, hygienic practices remain essential in herd management. (Am J Vet Res 2001;62:270–274)

Full access
in American Journal of Veterinary Research