Mastitis in small ruminants

Abstract

The importance of mastitis in small ruminants is important from the point of view of 3 perspectives: economic (mortality of animals, treatment costs, reduced quantity and quality of milk); hygienic (the risk of infection or poisoning of consumers by consuming infected milk), and legal (definitions of bacteriological milk quality). Coagulase-negative staphylococci are the most prevalent pathogens of the mammary gland in sheep and goats with subclinical mastitis (affecting from 45 to 48% in sheep and from 60 to 80.7% in goats). Prevalence of clinical mastitis in small ruminants is usually below 5%. Several pathogens can cause mastitis, but Staphylococcus spp. are the most frequently diagnosed causal microorganisms of intramammary infections in goats and sheep. Somatic cell counts in milk of dairy ewes can be used to define subclinical mastitis and a threshold of about 200,000 to 400,000 cells/ml will accurately identify most infected ewes. In ewe milk somatic cell counts between 300,000 cells/ml and 1,000,000 cells/ml cause changes in the composition and plasmin activity, and suggest that milk secretion is in a period of transition from normal to mastitic milk. In goats infected glands also lead to an increase in somatic cell counts; however, increased somatic cell counts in milk are also caused by other non-infection factors, such as estrus, season of milking, milk yield or stage of lactation. A standard tool in the diagnosis of mastitis for small ruminants is bacteriological examination of milk. During milking of small ruminants there is usually a transmission of Gram-positive bacteria, mainly Staphylococci. Therefore, the control of mastitis in small ruminants should take into account the optimal milking routine and milking hygiene. In particularly justified cases and the large prevalence of disease antibiotic treatment should be administered in the dry-period.