[3]. The following account is summarised from a bulletin of the Montana Experiment Station by Dr. Wilcox.
Severe losses have from time to time been recorded, especially in America, from larkspur poisoning, the number of animals lost amounting to thousands. The first signs of poisoning are slight general stiffness and straddling gait, especially of the hind legs. The stiffness becomes more and more pronounced, until walking is difficult and evidently painful. Soon there are manifested various involuntary twitchings of the muscles of the legs and sides of the body, and loss of control or co-ordination of the muscles. Ordinarily there is no increase in the quantity of the saliva, no dribbling of saliva from the mouth, no champing of the jaws or attempts at swallowing. The sheep manifest none of the mental disturbances frequently seen in cases of poisoning from other sources, as for example loco weed and lupine. There is no impairment of the special senses. The sheep seem to hear and see as well and as correctly as under normal conditions of health.
No indications of any disturbances of the digestive functions are to be seen. The appetite remains good, and the sheep eat up to the very last. They were observed eating industriously during the intervals between the attacks of spasms which they have during the last stages.
At first the frequency of the pulse and of the respiratory movements is lessened and the temperature is lowered. The pulse remains very weak, but in the later stages becomes very rapid, in some cases 130 per minute. Toward the last also the respiration is very shallow and rapid. During the final convulsions the respiration is sometimes 120 per minute, but so shallow that the air is simply pumped up and down the windpipe. The air in the lungs is therefore not renewed, and the animal dies by asphyxia or suffocation.
So long as the sheep can stand on its feet, or walk, it keeps up with the flock as nearly as possible. The exercise, however, excites it, makes its respiration more rapid, and it has frequently to lie down for a moment and then get up and hobble along after the flock. The worst cases can thus easily be detected, since they straggle behind the rest of the flock.
The later stages follow rather rapidly. The involuntary movements become more frequent and more severe. All four legs tremble and shake violently. In fact, all the muscles of the body contract spasmodically until the animal totters over on its side and dies in the most violent spasms.
Larkspur has the effect of arresting the heart’s action and respiration and of paralysing the spinal cord.
Treatment. Place the animal by itself in a cool, quiet, shaded place and avoid all excitement. Of the drugs tested, atropine sulphate dissolved in camphor water has given the best results. Wilcox (Bull. 15, Montana Ex. Station) recommends for sheep from ¹⁄₂₀ to ¹⁄₁₅ grain in the earlier, and ⅙ to ¼ grain in the later convulsive stages. Cattle require from four to five times these doses. Inhalations of ammonia vapour, and small doses of alcohol and ether, are also useful.
Fig. 81.—Delphinium menziesii.
(To illustrate “Larkspur Poisoning.” From the Annual Report, U.S.A.
Department of Agriculture, 1898.)