Plants Poisonous to Live Stock

by Harold Cecil Long

In some poor pastures it occurs in excessive quantity, and would appear to be only very slightly poisonous, or would have attracted wider attention. It is possibly only poisonous after being eaten for a prolonged period, as in the case of Lolium temulentum, and Lathyrus sativus. The seeds contain the bitter-sweet glucoside Rhinanthin (C₂₉H₅₂O₂₀), which is suspected of having poisonous properties.

Cow-Wheat (Melampyrum arvense L.). It seems clear that Cow-Wheat is at least not poisonous unless eaten in very considerable quantities—amounts in fact which in practice are most unlikely to be eaten. The seeds may occur in cereal grains, and hence be ground up into meal. As they are said to contain a glucoside analogous to Rhinanthin, have a bitter taste and peculiar odour, and impart a violet coloration to flour, their presence in cornfields is most undesirable. According to Pammel this plant induces sleepiness and colic.

Ground Ivy (Nepeta Glechoma Benth.) is, according to Schaffner, poisonous to horses. It contains a volatile oil and bitter principle, as also does Catmint (N. Cataria). In a case which came before the Board of Agriculture and Fisheries in 1906 three horses became ill with symptoms of poisoning, and the only weed found in the lucerne they were getting was Ground Ivy, and this was suspected but not proved to be the cause. In a further case, reported in 1909, eleven horses were believed to have been poisoned by this weed, and in one of the dead horses scarcely any food but Ground Ivy was found, and to it the veterinary surgeon in attendance attributed death. During preceding years several horses had died in the locality (Ely), owing, it was believed, to poisoning by the same weed. The losses, however, were not proved to be due to this plant.

In the Veterinary Journal (October, 1914, p. 515) poisoning of horses by this weed was noted (after Ferenczhazsy in the Recueil de Médecine Vétérinaire). The author observed nine cases of intoxication due to the weed, though it is stated that it “has occasioned no trouble in cattle and sheep that consumed it.” The symptoms in horses were “anxious look, dyspnœa, salivation, sweating, dilatation of the pupils, cyanosis, signs of pulmonary œdema.” Two horses died. In 1913 similar cases were observed by other owners, and terminated fatally.

Hooker states that N. Glechoma is “bitter and aromatic, formerly used for beer, occasionally for tea.”

Orache (Atriplex sp.). So far as known these plants are not poisonous, but it may be stated that Greshoff found the seeds of five species, and the leaves of two species, to contain a Saponin.

Nettles (Urtica sp.). Nettles are not generally regarded as poisonous otherwise than as causing painful nettle rash on the bare skin, but Urtica dioica L. is stated to have caused the death of dogs (Berliner Tierärztliche Wochenschrift, 1909).

Yellow Flag (Iris Pseud-acorus L.). The wild Flag was noted by Linnæus as dangerous to cattle, but no case of actual poisoning has been found in the literature. The plant is stated to have marked emetic and purgative properties, and Cornevin remarks that in Belgium intense gastro-enteritis is attributed to it. It contains the glucoside Iridin (C₂₄H₂₆O₁₃).

Narcissus sp. Various Narcissi (e.g. N. pseudo-narcissus, N. poeticus, and others) have been regarded as irritant to the hands. They would rarely if ever be eaten by live-stock in Britain, but it is stated that on the Continent many poisonings of cattle, goats, and pigs have been recorded, not infrequently ending in death after two or three days. The Narcissi are strongly narcotic, emetic, and purgative, and cause dilated pupils. Pott states that they cause inflammation of the digestive tract, and convulsions, sometimes with fatal results; and according to Pammel N. poeticus induces intense gastro-enteritis. N. pseudo-narcissus contains the alkaloid Narcissine (C₁₆H₁₇O₄N), which with cats causes nausea and purgation (Henry).

Common Fritillary (Fritillaria Meleagris L.). The Fritillary or Snake’s Head occurs only in a few places in England, and truly wild perhaps only rarely in southern and eastern counties—not in Scotland or Ireland. No definite case of poisoning has been found in the literature, but the plant is stated to be poisonous. It contains the bitter alkaloid Imperialine (C₃₅H₆₀NO₄), which is a heart poison.