Arcanobacterium pyogenes mastitis in a 18-month-old heifer

In New Zealand, the agent Arcanobacterium (formerly Actinomyces) pyogenes is commonly associated with suppurative diseases in cattle, including abscesses, chronic endometritis and embolic pneumonia, but is an uncommon pathogen in bovine mastitis. Overseas, A. pyogenes mastitis is widespread and usually sporadic. The source of infection is considered to be endogenous, as A. pyogenes can be recovered from the mucous membranes, skin, tonsils and genital tract of clinically normal cattle (Madsen 1987). Infection usually follows localised tissue damage from trauma, foreign body penetration or another infectious process. A. pyogenes has been reported in New Zealand review and surveillance data as causing sporadic disease in lactating cows (Carman and Gardner 1997; Vermunt and Parkinson 2000). However, there is little information available regarding A. pyogenes mastitis in noncalved heifers in New Zealand. This report describes a case of A. pyogenes mastitis in a primigravid dairy heifer.