Southwest herd loses two bullocks and a heifer to ragwort

A herd in the southwest of the country sustained multiple losses due to poisoning by ragwort, a regional veterinary lab (RVL) has said.

Limerick RVL reported that a herd submitted a number of animals in May 2023. The 2022-born cattle, two bullocks and a heifer, were necropsied (had post-mortem examinations performed).

The animals had been lethargic, had watery scour with blood in some cases and neurological signs such as wandering aimlessly, aggression and blindness.

The yearlings did not thrive over the winter compared to other years.

There were common findings from the necropsies in all three animals, including that the livers had a pale, firm texture and were difficult to cut, strongly suggestive of cirrhosis (end-stage liver disease).

There was a build-up of fluid causing swelling in the rumen, intestines and most noticeably, in the abomasum (the fourth stomach) of all animals. Testing for lead was negative.

Toxins

Microscopic examination of the animals’ tissue cells found toxins that are produced by over 6,000 plants as a deterrent to consumption by herbivores.

However, ragwort - also known as a buchalán - is the most common source of these toxins in Ireland.

The plant is usually not eaten by cattle, but when cut as silage or made into hay, it becomes more palatable due to the release of sugar. Animals that are very tightly grazed may have no option but to eat the plant.

The affected cattle were housed in December and turned out again in mid-March. The cattle were all fed silage which had been baled from the same fields for the last number of years.

During a farm visit by the RVL, ragwort rosettes (the low-growing, non-flowering form of the plant in its first growing year) were identified in many fields with varying degrees of cover.

The paddock for cows and calves had the heaviest contamination and the silage fields also contained a significant amount of ragwort rosettes.

The fields were searched for other poisonous plants, but none were found.

Northern Ireland

Meanwhile, in Northern Ireland there has recently been an increase in submissions of carcases to the Agri-Food and Biosciences Institute (AFBI) veterinary lab, where the animal was exposed to ragwort.

The cases submitted to AFBI for analysis involved multiple deaths in bovines around 12 to 18 months old, which is unusual given clinical signs are normally seen in older animals after weeks to months of ingestion.