Test characteristics from latent-class models of the California Mastitis Test.
We evaluated (using latent-class models) the ability of the California Mastitis Test (CMT) to identify cows with intramammary infections on the day of dry-off. The positive and negative predictive values of this test to identify cows requiring dry-cow antibiotics (i.e. infected) was also assessed. We used 752 Holstein-Friesian cows from 11 herds for this investigation. Milk samples were collected for bacteriology, and the CMT was performed cow-side, prior to milking on the day of dry-off. At the cow-level, the sensitivity and specificity of the CMT (using the four quarter results interpreted in parallel) for identifying all pathogens were estimated at 70 and 48%, respectively. If only major pathogens were considered the sensitivity of the CMT increased to 86%. The negative predictive value of the CMT was >95% for herds with major-pathogen intramammary-infection prevalence <15%, so that selective dry-cow therapy might be reasonable for such herds if cows were screened with the CMT.
Sanford
C J
CJ
Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PEI, Canada. sanford@pei.sympatico.ca
Keefe
G P
GP
Sanchez
J
J
Dingwell
R T
RT
Barkema
H W
HW
Leslie
K E
KE
Dohoo
I R
IR
D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001424:Bacterial Infections / Q000175:diagnosis / Q000382:microbiology / Q000662:veterinary*; D001431:Bacteriological Techniques / Q000662:veterinary; D001499:Bayes Theorem; D002140:California; D002417:Cattle; D005260:Female; D007774:Lactation; D008321:Mammary Glands, Animal / Q000382:microbiology; D008414:Mastitis, Bovine / Q000175:diagnosis* / Q000382:microbiology*; D011237:Predictive Value of Tests; D011247:Pregnancy; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D000900:Anti-Bacterial Agents