Summer mastitis or dry cow mastitis is a common condition affecting cows and heifers in Ireland. It is caused by the bacteria Arcanobacterium pyogenes and anaerobes such as Peptostreptococcus indolicus, and as the name suggests is primarily seen between May and September.

In terms of general mastitis prevention, the most important anatomical defence of the cow is the integrity of the teat end or teat orifice.