Dr. Wilcox has observed that sheep are especially fond of the pods of various leguminous plants before they become mature and while they are still in a succulent condition.
Dr. Wilcox saw a flock of sheep which while being driven from one range to another, in a hungry condition, was allowed to feed upon an area of lupines in a nearly ripe condition. Within two hours the sheep manifested violent symptoms of poisoning, and ultimately 100 out of the lot of 200 died. He afterwards saw many hundreds of fatal cases in sheep and a number in horses, both from eating green lupines and lupine hay.
As an experiment two sheep were given each 150 medium-sized lupine pods (L. leucophyllus) which were entirely full of ripe seeds. The sheep ate the pods readily. Both sheep became frenzied within about forty-five minutes after feeding upon the lupine pods, and died about one hour later. The symptoms in these cases were the same as those observed in poisoning under natural conditions.
The symptoms of lupine poisoning are so well known in Europe that chronic lupine poisoning has been given the name lupinosis. It is characterised by loss of appetite, fever, dyspnœa, constipation, and yellowness of the visible mucous membranes. Diarrhœa, sometimes of a sanguinolent type, appears later. The urine becomes albuminous, tinted with bile products or stained red by hæmoglobin, and the head shows œdema. Death occurs in a few days. In America the chronic form has not been observed. In cases of lupine poisoning in Montana there was noted acute cerebral congestion, accompanied with mental excitement. The sheep rushed about in different directions, butting one another and other objects. The first stage of frenzy was soon followed by a second stage, characterised by pronounced irregularity of movement, spasms, and falling fits. In the majority of cases death occurred in from one-half to one and one-half hours. In extensive cases of lupine poisoning it was uniformly observed that a number of the sheep lingered on from two to four days before they died. The muscular convulsions resembled those caused by strychnine. The excretion of the kidneys was much increased and frequently was bloody. Post-mortem examinations of sheep poisoned by lupines revealed conditions similar to those in acute forms of loco disease, with the addition of a congested condition of the kidneys.
Fig. 94.—Lupine (Lupinus leucophyllus).
(From the Annual Report, U.S.A. Department of Agriculture, 1900.)
Fig. 95.—Lupine (Lupinus leucophyllus) in hay.
(From the Annual Report, U.S.A. Department of Agriculture, 1900.)
No remedies have been tried in cases of poisoning from American species of lupine, but it seems reasonable to suppose that potassium permanganate would probably destroy the lupine alkaloids in the stomach if administered promptly after the first signs of poisoning. Experience and observation indicate that lupine hay is always dangerous for sheep if cut at a time when the seeds are retained in the hay. The evidence thus far collected regarding this matter indicates that the seeds are the most poisonous part of the plant.