Warfarin is one of a group of chemicals (rodenticides) that are used to control rat and mice populations. Poisoning by these substances is common in pigs due to accidental exposure. A single dose of warfarin of 3mg/kg is fatal. Doses of less than 0.06mg per day for seven to ten days will produce poisoning. Warfarin acts by preventing blood clotting.

Clinical signs

Severe haemorrhage is present throughout the carcase of dead pigs and in the skin, particularly where trauma has occurred. Lameness with haemorrhage in the joints and anaemia are consistent features.


This is based on the history of the use of warfarin and the typical post-mortem lesions of widespread haemorrhage throughout the carcase.


  • Give injections of vitamin K, 5mg/kg on day one and then 2mg/kg daily for five days.