The chronic form, which occurs when small doses are repeated over a long period (practically the only form found in human beings, but never in animals, except perhaps in the pig) is characterized by gradual wasting away, loss of breath, loss of strength, chronic diarrhœa, and nerve troubles, death taking place in marasmus and decline. The active principle acts as an irritant on the digestive tract, causing colic, diarrhœa and enterorrhagia.
Cornevin describes the symptoms in the acute form of the poisoning in the case of horses, cattle, pigs and dogs.
In the horse, if a small quantity only is taken, there is yawning, heavy colic, stamping and evacuation of rather soft fæces. If larger quantities are taken, the symptoms, which commence in about an hour, are salivation, frequent yawning and turning of the head, colic, pale mucus, hurried and weak pulse, rise in temperature and accelerated respiration. Some time later there are muscular tremors succeeded by pronounced rigidity, and the fæces are diarrhœic and fœtid. The animal lies down, and getting up is painful; it falls into a kind of coma, stretches itself to the utmost, and death takes place without convulsions.
In cattle, the symptoms observed one hour after eating are restlessness, salivation, and grinding of the teeth. Excitement and colic are followed sometimes by coughing, this state lasting from five to eight hours. There is then a period of coma, characterized by permanent decubitus, repeated fœtid diarrhœa, hurried and plaintive respiration, accelerated and gradually weakening pulse, a gradual loss of motor and sensory powers, and a progressive decline in temperature. Death occurs in twenty-four hours.
In the case of pigs, the animal grunts, lies down and remains thus with its snout embedded in the straw. There is vomiting, more or less violent colic and diarrhœa, the evacuation consisting of bad-smelling, spumous fæcal matter. At times there are clonic contractions. Young pigs are most susceptible.
Pott cites cases in which abortion was a feature of the poisoning, both in cows and pigs. The results of numerous experiments which he quotes (among others some carried out for the Prussian Ministry of Agriculture) are very contradictory, a small quantity causing death in some animals, while others of the same species were left unharmed by large quantities. He ascribes this to the very variable proportions of the poison present in the seeds.
REFERENCES.
[4], [16], [28], [46], [52], [53], [63], [76], [81], [82], [144], [161], [172], [184], [190], [203], [205], [213], [249].
HYPERICINEÆ.
St. John’s Wort (Hypericum perforatum L.). There appears to be no record of poisoning of live stock by this plant in Britain, but Cornevin records that it injured breeding mares fed on lucerne containing it in large proportion. Drying in converting into hay did not render it innocuous. It is only poisonous if eaten in considerable quantity, and in general animals are not likely to eat much of it voluntarily, owing to its resinous odour when crushed, and a bitter and slightly saline taste.