CASE NOTES
Pyrrolizidine Alkaloid Poisoning in Cattle — Case 1
Ian Masters, District Veterinarian, Hume LHPA (Gundagai)
Posted Flock & Herd August 2010
History
A producer in the Cootamundra district contacted me in late June 2009 concerned about losses in young cattle. He had purchased a mob of 96 drought affected angus and angus cross weaners via the Wagga Saleyards at the start of the year. The cattle had been on the Cootamundra property for about 6 months before significant losses were noticed. The area was drought affected over summer and autumn but we had a reasonable break in early winter and major losses started when the mob was moved onto an oat crop sod sown into a pasture paddock with access to 18% CP calf pellets provided in self feeders.
At the time I visited the property he had lost 20 animals over recent weeks with another 5-6 animals obviously unwell. The owner stated that most of the animals that had died were severely depressed, poorly grown with a gut full of water that you could hear sloshing around when they moved. Several had died or were destroyed after developing a rectal prolapse.
Post-Mortem findings
The owner destroyed one animal with a very bad rectal prolapse for autopsy. The animal was stunted, in poor condition with a rough coat and distended abdomen. On PM this was a typical chronic PA poisoning case with ascites, gross oedema of mesenteries and intestines, impacted omasum , scattered haemorrhages and severe fibrosis of the liver. The owner did not want any specimens submitted to the laboratory to confirm my diagnosis. The property of origin was traced via the NLIS data base. It was a property located on the lower Lachlan River flood plain in the former Balranald RLPB district.
Discussion
The Balranald property was badly infested with bushy groundsel (Senecio cunninghamii) during the time I worked as DV Hay and I had investigated previous cases of PA poisoning in cattle off this property. There are several plants capable of causing PA poisoning in cattle on most properties in this area but the major losses I looked into during my time out there were on properties badly infested by bushy groundsel. It is a tough plant and does not appear to be readily eaten by stock but during drought conditions it is one of the few plants that remain soft and green. Under these conditions weaners can't afford to be too fussy.
Involuntary ingestion of young seedlings growing in a mix of feed along creek beds and channels may also play a role. Shrunken, grey obviously fibrotic livers in cattle under twelve months of age are typical of animals exposed to this plant. A lot of these animals can be in reasonable condition despite advanced liver damage. Deaths are triggered by stress or improved nutrition. They do not handle high protein diets. In the case outlined above 48 weaners died before the owner called a halt and sent the rest to slaughter.