Three ewes died in January after it was established by Athlone regional veterinary laboratory that they had consumed rhododendron.

The lab examined three of 11 in-lamb ewes in January. The ewes had been found dead at pasture.

During examination of the carcases, similar lesions were found in all three ewes, with severe congestion or haemorrhage into the kidneys and lungs bilaterally.

Multiple suspicious plant remnants were identified by vets within the rumen rafts of all examined ewes.

The National Botanic Gardens confirmed the suspicious plant remnants identified in the ewes to be a species of the Rhododendron family (Pieris japonica variegata).

Highly lethal

“These plants contain large amounts of grayanotoxin, which is highly lethal to sheep,” according to the Department of Agriculture.

“Toxicity is dose-dependent, but 100g to 200g can be lethal. Grayanotoxins block sodium transport channels in cell membranes causing both cardiac and skeletal muscle dysfunction and also nerve dysfunction. Hypersalivation, bruxism and vomiting are typical clinical signs.

“Further investigation and expansion of the clinical history determined that the ewes had broken into a garden the preceding evening,” it added.