Cases of poisoning due to hay feeding, crop up from time to time. Now it is Dutch, and next Canadian, but mostly foreign food-stuffs that cause illness in horses in this country. The deleterious ingredient has not always been traced, but it would seem that animals bred upon a particular pasture gain immunity from the effects of herbage which causes illness in others, or else develop a power of selection which enables them to reject certain poisonous plants even when compressed in form of hay.
Fig. 460. - Colchicum autumnale.
Fig. 461. - Alfalfa (Medicago saliva).
In the low pastures of Flanders we have seen much Colchicum (fig. 460) growing, and observed that native stock carefully avoid it, but when made into hay and imported into this country it may be that animals in our great cities, drawn from all sorts of sources, are not able to distinguish it. The dry, hard grasses, chiefly alfalfa (fig. 461), upon which American horses are fed, are not acceptable to home-bred animals until the taste is acquired, but horses imported from the United States and Canada eat it and thrive upon it. The presence of a large portion of Starwort (Stellaria Holostea) (fig. 462) in imported hay has been said to occasion poisoning in a number of cases of horses fed upon it.
There is much resemblance in the symptoms of poisoning arising out of deleterious legumes or grasses, the commonest being staggering or want of co-ordination of the muscles, particularly of the hind-limbs, weakness amounting to prostration, swelling of the lower portions of the limbs, fever, redness of the membranes, sweating, and an inability to walk straight or endure any exertion.
Beyond change of diet there is little to be done in these cases, as we have to deal with an unknown quantity and can only attempt the amelioration of symptoms. It is good practice to give a mild aperient, with the object of getting rid of the offensive matter contained in the alimentary canal, and to follow it up with stimulants and tonics. In this connection nux vomica is especially indicated when inco-ordination persists after appetite returns and febrile symptoms have disappeared.
In these cases the hay in use should be subjected to the closest scrutiny in order to determine, if possible, the actual ingredient giving rise to the trouble.