Farm records in investigation of epidemiology, symptomatology and causes of clinical mastitis in a dairy farm

Mastitis is one of the most important diseases in dairy cow farms and one of the most common cause for antibiotic treatment. Aims of this study were: to investigate frequency and trends of clinical mastitis in cows on a large dairy farm, describe clinical characteristics of mastitis and investigate causative infectious agents in selected cases alongside antimicrobial resistance. In our study we used farm records for clinical mastitis recorded for period 2016 and 2017. We also used results of the regular on farm testing of the somatic cell count for 2017. Samples of milk from all clinical mastitis cases were taken during November and December 2017 in order to investigate causative agents and their antimicrobial resistance. Occurrence of clinical mastitis was 205 cases (47.7%) in 2017 compared to 93 cases (29.7%) recorded in 2016. In 2017 reoccurrence of clinical mastitis in same animal was recorded for 93 cows (45.4%). In 2016 reoccurrence of clinical mastitis in same animal was recoded for 49 cows (29.7%). Average course of clinical mastitis in 2016 was 3 days, while in 2017 4.5 days (continuous days of recording a case in farm records). Somatic cell count in more than half of tested animals was higher than 200.000 SC/ml according to the measurements from February and July 2017 (number of cows tested 236 and 169, respectively). Out of 23 milk samples, 20 had bacteriological growth. In 9 samples we identified S.aureus, in 6 streptococcus spp., in 4 coagulase negative staphylococci (CNS) and one sample contained E.coli. Most common resistance was found for lincomycin-spectinomycin (100%) gentamicin (92%), followed by cefquinome (65%), linkomycin (53%) and erythromycin (47%). Isolates of S.aureus were resistant on the largest number of investigated antibiotics.