The objectives of the present study were to evaluate the efficacy of intra-mammary-administered cefquinome for the treatment of sub-clinical mastitis in lactating dairy cows and to determine if extended therapy would enhance treatment efficacy. Seventy-three Holstein dairy cows from a single farm with 150 infected quarters were enrolled in the study. Infected cows were allocated randomly to one of three treatment regimens: (1) conventional (standard) regimen: 75 mg of cefquinome administered three times at 16-h intervals (25 infected cows, 52 intra-mammary infections (IMI)), (2) extended regimen: 75 mg of cefquinome administered six times at 16-h intervals (26 infected cows, 58 IMI) and (3) negative untreated control group (22 cows, 40 IMI). Most IMI were caused by coagulase-negative staphylococci, streptococci other than Streptococcus agalactiae and coliforms. The overall bacteriological cure (BC) rates for sub-clinical IMI were 84.61%, 91.37% and 20% for the conventional, extended and the control groups, respectively, indicating a higher BC rate for the treated groups than the control group (P < 0.001). Significant differences in somatic cell count (SCC) were detected between the treated versus the control group (P < 0.001). No differences, concerning the BC rate or SCC, were observed between the extended and the conventional groups. Although fat and protein percentages increased in the treated groups, there were no significant differences in post-treatment milk production between the groups. Results of this study indicate that cefquinome therapy was effective in reducing SCC and eliminating sub-clinical IMI in lactating dairy cows, but extended therapy did not enhance treatment efficacy.

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The present report identifies a statistically significant (P < 0.001) higher postoperative culling rate in cows with left displaced abomasum (LDA) exhibiting diarrhoea, compared with cows with LDA and normal faeces from a large Holstein dairy herd (odds ratio = 34). Paratuberculosis was histopathologically confirmed in 77.0% of cows with LDA exhibiting diarrhoea.

Environmental and minor pathogens seem to be of increasing significance, especially in situations where major contagious pathogens (Streptococcus agalactiae and Staphylococcus aureus) have been controlled using post-milking teat disinfection and dry cow therapy. Herd management practices that successfully control contagious pathogens fail to control coliforms and many streptococcal bacteria. Coagulase-negative staphylococci (CNS) are the most prevalent bacteria isolated in herds using currently recommended control measures and Corynebacterium bovis ( C. bovis) was identified as the cause of up to 20% of all cases of clinical mastitis in some herds.

Due to the obligate nature of Streptococcus agalactiae, its presence in bulk tank milk (BTM) is the exclusive result of shedding of bacteria from infected quarters. Consequently, BTM has a very high specificity, but a low sensitivity for identifying S. agalactiae at the herd level when using traditional milk culture techniques. The objective of this study was to determine the association of the bulk tank culture results with the results of the corresponding cow milk cultures for S. agalactiae in two dairy herds in Iran.