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  • Author or Editor: Suzanne N. Gibbons-Burgener x
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Objective—To determine the likelihood of false-positive results when testing milk samples from individual cows by use of 3 commercially available assays (Penzyme Milk Test and the SNAP β-lactamand Delvo- SP assays) labeled for use with commingled milk.

Sample Population—Milk samples from 111 cows with mild clinical mastitis.

Procedure—Cows were randomly assigned to the control (no antimicrobials) or intramammary treatment group. Posttreatment milk samples were collected at the first milking after the labeled withholding period or an equivalent time for controls, randomly ordered, and tested twice by use of each assay and once by use of high-performance liquid chromatography. Sensitivity, specificity, and positive and negative predictive values were determined for each assay. Concordance of results for the same sample was assessed for each assay by calculating κ.

Results—Sensitivities of the Delvo-SP and SNAP β-lactam assays were > 90%, whereas the sensitivity of the Penzyme Milk Test was 60%. Positive predictive values (range, 39.29 to 73.68%) were poor for all 3 assays. Concordance of test results was excellent for the SNAP β-lactam and Delvo-SP assays (κ = 0.846 and 0.813, respectively) but was less for the Penzyme Milk Test (κ = 0.545).

Conclusions and Clinical Relevance—Because of the low positive predictive values, these 3 assays may not be useful for detecting violative antimicrobial residues in individual milk samples from cows treated for mild clinical mastitis. However, repeatability of each assay was considered good to excellent. (Am J Vet Res 2001;62:1716–1720)

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in American Journal of Veterinary Research


Objective—To compare the findings of light microscopic evaluation of routine unstained wet-mounted preparations and air-dried, modified Wright-stained preparations of urine sediment with results of quantitative aerobic bacteriologic culture of urine.

Design—Masked prospective study.

Sample Population—459 urine samples collected by cystocentesis from 441 dogs.

Procedure—Urinalyses and quantitative bacteriologic cultures of urine were performed. Unstained wetmounted preparations and air-dried, modified Wrightstained urine sediment preparations were examined by light microscopy for the presence of bacteria.

Results—Compared with results of quantitative bacteriologic culture, routine unstained preparations and modified Wright-stained preparations had sensitivities of 82.4% and 93.2%, specificities of 76.4% and 99.0%, positive predictive values of 40.1% and 94.5%, negative predictive values of 95.8% and 98.7%, and test efficiencies of 77.3% and 98.0%, respectively. Compared with 74 samples that yielded growth on bacteriologic culture, the routine unstained method had concordance and misclassification rates of 39.2% and 60.8%, respectively, whereas the Wright-stained method had concordance and misclassification rates of 78.4% and 21.6%, respectively. Significant associations between each of occult blood in urine, pyuria, female sex, and lower urine specific gravity with bacteriuria detected by Wright-stained sediment examination and quantitative bacteriologic culture of urine were identified.

Conclusions and Clinical Relevance—Examination of modified Wright-stained preparations of urine sediment appeared to be a rapid, cost effective method that significantly improved the sensitivity, specificity, positive predictive value, and test efficiency of light microscopic detection of bacteriuria, compared with that of the routine unstained method. (J Am Vet Med Assoc 2004; 224:1282–1289)

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in Journal of the American Veterinary Medical Association


Objective—To test the hypothesis that dairy farms certified in the Milk and Dairy Beef Quality Assurance Program (QAP) were more likely to use prudent drug management practices than farms that were not certified.

Design—Cross-sectional study.

Sample Population—141 Michigan dairy farms of which 74 were not certified in the QAP, 30 were involuntarily certified, and 37 were voluntarily certified.

Procedure—Dairy producers completed a self-administered questionnaire that focused on herd health management, drug use, record keeping, personnel management, and descriptive characteristics of their farm during 1993. Separate multivariable logistic regression models were developed to determine the association of QAP certification with each of the management practices.

Results—Results suggested that farms adopted specific management practices irrespective of certification. Many farms used visible identification and nonemergency veterinary services and discussed residue prevention with employees. Involuntary certification was associated with maintenance of good written treatment records and performance of on-farm drug residue testing. Voluntary certification was weakly associated with use of refrigerated drug storage.

Conclusions and Clinical Relevance—QAP certification appeared to have been associated with the adoption of only a few prudent drug use practices, although QAP materials and framework were developed to assist veterinarians in the promotion of disease prevention, client communication, and residue prevention practices on farms. Veterinary care would benefit from the development and encouragement of better record keeping on farms. (J Am Vet Med Assoc 2000;216:1960–1964)

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in Journal of the American Veterinary Medical Association



To determine whether certification in a Milk and Dairy Beef Quality Assurance Program (MDBQAP) was associated with a reduced risk of having antibiotic residues in milk and to define specific management factors that may have predisposed dairy farms to having violative antibiotic residues in milk.

Sample Population

124 dairy farms in Michigan that had ≥ 1 violative residue in milk during 1993 and 248 randomly selected control farms in Michigan that did not have violative residues in milk during 1993.


A pretested structured questionnaire was mailed to case and control farms. A conditional multivariate logistic regression model was developed to determine risk factors associated with having a violative antibiotic residue in milk.


Certification in the MDBQAP did not significantly reduce the risk of having a violative antibiotic residue. Annual treatment of > 10% of a herd for metritis was associated with a reduced risk of having a violative residue. Evidence suggested that a routine request for a milk processor to perform residue testing was associated with a decreased risk of having had a violative antibiotic residue, but routine on-farm residue testing was associated with an increased risk of having had a residue.

Conclusions and Clinical Relevance

MDBQAP certification was associated, although not significantly, with a reduced risk of having violative antibiotic residues in milk. Risk factors significantly associated with violative antibiotic residues are addressed by various critical control points in the MDBQAP and may be indicators for strengths and weaknesses of MDBQAP. (Am J Vet Res 1999;60:1312–1316)

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in American Journal of Veterinary Research