The within-farm prevalence of vulva biting in breeding sows in south-west England was investigated using a postal survey sent to 410 pig farmers in January 1997. The response rate was 65 per cent and there were 83 useable replies. The majority of farms where vulva biting was reported indicated a low within-farm prevalence of 1-9 per cent of sows affected, although prevalences as high as 30-60 per cent were reported. The injuries reported ranged from bleeding to removal of the whole vulva, the most commonly reported injuries being bleeding and superficial damage to the vulva. No long-term effects from this injury to service and dry sows were reported by 70 per cent and 76 per cent of farmers respectively. Competition for food, aggressive sows, closeness to farrowing and mixing of sows were the most common reasons suggested by these farmers as causes of vulva biting.
