Cow specific risk factors for mastitis caused by prototheca spp.

Risk faktors for mastitis caused by Prototheca zopfii were determined in a retrospective case control study. 248 cows culled for protothecal mastitis in a large dairy herd were included in the study. The diseased cows were co mpared to their non affected herdmates in respect to age, stage of lactatio n, production and milk composition. The effect of previous cases of mastiti s during the same lactation or in previous lactations and the effect of ant ibiotic pretreatment were determined in a split udder analysis comparing le ft quarters to right quarters. Age and mastitis history especially antimicrobial pretreatment were importa nt risks factors for developing protothecal mastitis. Risk of protothecal m astitis increased with parity. Quarters with a history of clinical mastitis during the same or during previous lactations were at higher risk than oth er quarters (OR 1.98, p < 0.01 and 1.44, p = 0.06, respectively). Pretreatm ent with antibiotics increased the risk of protothecal mastitis (OR 3.19, p < 0.001). Milk yield was fewer in cows that developed protothecal mastitis . Somatic cell counts were higher than in control cows. incidence of protot hecal mastitis peaked in the second month of lactation.