=Eradication of Poisonous Plants.= Wherever poisonous plants are found, particularly in quantity, where they are liable to be eaten by live stock, an attempt should be made to eradicate them. They may be simply dealt with as weeds as may be necessary according to the species concerned. When any difficulty is experienced in regard either to determination of the species or to methods of eradication the advice of the Board of Agriculture and Fisheries (Whitehall Place, London, S.W.) should be requested. Stock should at once be removed from a suspected pasture, which should be immediately and thoroughly examined by a competent botanist. Harmful plants should be eradicated and their place filled by better herbage.
=Treatment of Poisoned Animals.= This volume makes no pretensions to deal with the veterinary treatment of cases of plant poisoning. Whenever poisoning is suspected the services of a veterinary surgeon should be sought without delay; the text books at his disposal will aid him in the treatment of any case which presents unusual difficulties. The symptoms indicated in the following pages, together with the possible discovery of a suspected plant, may be utilised in diagnosis.
=Tests with Suspected Plants.= The action of plants on animals may be ascertained (1) by observing the effects in cases in which it has been established that the plants have been eaten, or (2) by direct experimental feeding of animals with the plant. In the first case the results may be accurate and satisfactory if observations have been made from the outset.
As regards (2) the results may or may not be satisfactory according as the plan pursued is sound or otherwise. For example, it cannot be considered altogether reasonable and satisfactory to extract the principles present in the plant, inject them into the blood stream, and conclude from any ill effects that the animal may exhibit that the plant is poisonous, since the substance extracted may be poisonous under such conditions but little or not at all harmful when the plant is eaten in the small quantities commonly taken by animals. Again, it cannot be held satisfactory to feed an animal on a heavy and exclusive diet of the suspected plant for a considerable period. The real test would, in general, consist in a feeding trial in which the suspected plant occupied a place in the ration in reasonable quantity—such a quantity as might well be taken in natural circumstances, in view of its relative abundance in regard to other food available; and if considered likely that the plant would be eaten daily it may be fed regularly for some days. Should such a test prove negative it may generally be held that the plant is not poisonous, or only so in exceptional circumstances.