Haemolytic crisis associated with ragwort poisoning and rail chewing in two thoroughbred fillies

Events leading to the deaths of two fillies at pasture are described. Pasture hay containing the flowering stages of Senecio jacobea (ragwort) had been fed three to four months earlier. Paddocks were subdivided with posts and rails treated with copper chrome arsenate. Six horses on the property chewed rails spasmodically. Both fillies presented with haemoglobinurea. Values in liver of 83 mg Cu kg and kidney 35 mg Cu kg wet weight and serum 1.4 mg Cu/l together with histophathology of seneciosis support a sequence of ragwort poisoning followed by copper accumulation in liver and kidney terminating in a haemolytic crisis. The source of copper appeared to he from wood containing concentrations of copper of 0.17% at the core and 1.68% in shavings from surface of treated timber.