554 



MANUAL OF POISONOUS PLANTS 



Fig. 304. Alfalfa (Medicago sativa). a, b, 

 seed pod; c, seed. An e.xcellent forage plant, some- 

 times causes bloat. (U. S. Dept. Agr.) 



"The cause of this trouble among horses and mules is not positively 

 understood. Whether the toxic effect is due to the plant itself, which possibly 

 undergoes some change within the digestive tract and subsequently liberates 

 a poison, or whether it is due to the presence of a mould in connection with 

 alsike clover, is still undetermined. The mould has been strongly suspected. 

 To determine this point will require further investigation. It is known, how- 

 ever, that the principle lesions arc produced on the skin and mucous membranes. 



"The symptoms of this disease vary to some extent, depending upon the 

 location of the lesions and the length of time the animal remains on the alsike 

 pasture after the symptoms begin to develop. The cases which came under 

 observation in Marshall County showed marked similarity of symptoms, involv- 

 ing principally the skin, the mucous membranes of the mouth, and the eyes. 



"The prevailing symptoms of the disease are as follows : 



On the skin are inflamed areas, appearing at first as more or less rounded 

 vesicular swellings, varying from one-half inch to five or six inches, or more, 

 in diameter. The hair over the affected areas stands erect, and "has a dull 

 appearance, indicating loss of vitality. Later the skin becomes hard and puffed 

 out, as the result of the formation of pus underneath. Finally, the deadened 

 skin is cast off, leaving a deep, raw, angry-looking ulcer, which eventually 

 heals, with the formation of a conspicuous scar, covered with more or less 

 white hair. These changes in the skin may occur on any part of the animal, 



