Factors Affecting Cure and Somatic Cell Count After Pirlimycin Treatment of Subclinical Mastitis in Lactating Cows

• Published in: Journal of dairy science 2005-02, Vol.88 (2), p.604-614
• Main Authors: Deluyker, H.A., Van Oye, S.N., Boucher, J.F.
• Format: Article
• Language: English
• Subjects: Animal productions; Animals; Anti-Bacterial Agents - administration & dosage; Anti-Bacterial Agents - therapeutic use; Biological and medical sciences; bovine mastitis; Cattle; Cell Count; Clindamycin - administration & dosage; Clindamycin - analogs & derivatives; Clindamycin - therapeutic use; dairy cows; drug therapy; duration; Female; Food industries; Fundamental and applied biological sciences. Psychology; lactating cow; lactation stage; Mammary Glands, Animal - drug effects; Mastitis, Bovine - drug therapy; Mastitis, Bovine - microbiology; Milk - cytology; Milk - microbiology; Milk and cheese industries. Ice creams; parity (reproduction); pirlimycin; somatic cell count; Staphylococcal Infections - drug therapy; Staphylococcal Infections - veterinary; Staphylococcus aureus; Streptococcal Infections - drug therapy; Streptococcal Infections - veterinary; subclinical mastitis; Terrestrial animal productions; Treatment Outcome; Vertebrates
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.S0022-0302(05)72724-7

This study investigated the associations of both bacteriological cure and quarter somatic cell count (SCC) after intramammary antibiotic treatment with treatment duration, cow characteristics, and pretreatment bacteriology and SCC. For the purpose of this paper, data from 2 treatment groups in each of 2 multi-location studies were selected. These studies were conducted to evaluate the efficacy of daily intramammary infusions with 50mg of pirlimycin hydrochloride for the treatment of subclinical mastitis. Data from study 1 allowed for comparison of a group of cows that received pirlimycin intramammarily for 2 d with a group that received no treatment, and study 2 provided data for comparison of pirlimycin for 2 d with pirlimycin for 8 d. Quarter milk samples from cows with a high monthly SCC were tested for bacteriology and SCC. If one or more quarters had both a positive bacteriology and an SCC ≥300,000 cells/mL, the cow was enrolled and randomly allocated to a treatment group. Enrolled cows were monitored for clinical mastitis and other disease for 4 wk after treatment initiation. At 3 and 4 wk after treatment initiation, milk samples were taken from each enrolled quarter to determine the SCC and conduct a bacteriological culture. Bacteriological culture results were interpreted such that quarters where the same bacterial species was cultured before treatment and found in at least 1 of the 2 posttreatment samples were considered a failure. The analysis of SCC used a mixed linear model (SAS proc mixed) and the analysis of bacteriological cure used a mixed logistic model (SAS glimmix macro). Bacteriological cure rate was significantly higher for lower parity, lower number of colonies in the pretreatment culture, longer treatment duration, and for streptococci compared with Staphylococcus aureus. However, treatment regimen affected bacteriological cure differently in major than in minor pathogens and there was a significant interaction of treatment regimen with stage of lactation. Posttreatment SCC was significantly higher with increasing parity, in rear quarters, and with shorter duration of treatment. In the group of second and third parity animals, post-treatment SCC was more reduced in front quarters than in rear quarters. Also, the difference in posttreatment SCC between younger and older cows increased with higher pretreatment SCC. In conclusion, when predicting bacteriological cure following treatment of subclinical mastitis during lactation both trea