[Iatrogenic mastitis in sheep]

Cases of ovine mastitis due to the use of dry-cow injectors are reported by the present authors. The inflammatory lesions were characterised by necrosis of mammary tissues, metaplasia of the epithelium of minor ducts and the appearance of macrophages and foreign-body giant cells. This is believed to have been caused by a mineral oil in an ointment base which was part of the material injected. However, injection of a different formulation using paraffin phenol also induced slight inflammatory lesions. Infection with maedi could not be ruled out in these cases. When drying off sheep is carried out as a routine procedure, it is recommended to refrain from using dry-cow injectors. Flocks in which there is a high incidence of mastitis require another, adapted approach.