LAUREL POISONING IN STOCK.

New Zealand Journal of Agriculture, Volume XXXVII, Issue 6, 20 December 1928, Page 407

LAUREL POISONING IN STOCK.

A CASE OF DEATHS AMONG CALVES.

D. A. Gill, M.R.C.V.S., D.V.S.M., and P. McGregor, M.R.C.V.S.,

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Division.

That the public in general, as well as those in charge of stock, should remember that laurel is poisonous is well exemplified by a recent case of which the following is a brief account. s ’

In a certain township in Central Otago four weaner calves running out on the commonage died within twenty-four hours. The symptoms shown were sudden and acute. The beasts went down and lay struggling convulsively on the ground, frothing at the mouth and showing acute distress. After about ten minutes the convulsions ceased and the animals died quietly. In each of the four cases the illness only lastedfrom the first signs till death occurred —about twenty minutes.

The last calf affected died in the evening, and a post-mortem examination was made next morning. The only abnormalities found were an inflamed condition of the fourth stomach and the small gut. The symptoms shown and the rapid death suggested that the calves had eaten some plant from which hydrocyanic acid (prussic acid) had been generated in the stomach. There are a number of plants and plant-products capable of this, and one of the commonest is the cherrylaurel (Prumis laurocerasus). ■. . .

Inquiries were made, but apparently there, was . no laurel growing on the commonage or in the surrounding gardens, and it began to appear that this could not have been the cause. However, on making a thorough inspection several branches of the plant, some of which had obviously been partly eaten, were found in a piece of swamp by the roadside. Some time previously the local hall had been decorated in connection with a function held there, and a large amount of laurel had been brought in from the neighbourhood for the purpose. . Later it was pitched out, and some children had dragged a large branch of it on to the commonage. Here much of it had withered, but that which had fallen into the swamp was still quite green and . fresh. , -

All of this material that could be found was immediately collected and disposed of, and that the trouble with calves running on the commonage immediately ceased was sufficient confirmation of the diagnosis.

The leaves of cherry-laurel are poisonous to stock because in them is a substance called amygdalin and an enzyme (ferment), which under suitable conditions of heat and moisture interact to produce hydrocyanic or prussic acid. When the leaves are masticated and swallowed, conditions in the animal’s stomach favour the rapid production of the poison, and death very quickly ensues. The inflammatory condition found present in the fourth stomach and small gut is not due to the hydrocyanic acid, but to an oily substance, something like turpentine, which is also present in these leaves.