22 MANUAL OF POISONOUS PLANTS 



moulds, or when at pasture, they have had access to grass which, for 

 various reasons, has become fermented or mouldy. Various micro-organisms 

 have been found to be associated with the disease, but as yet none have been 

 proven to possess any etiological significance. Cultural and histological studies 

 have all proved negative. Dr. Moore has in one instance succeeded in obtaining 

 a pure culture of the colon bacillus from the brain. 



symptoms. Depending upon the severity of the attack, tne disease may 

 manifest itself in any one of three forms, namely; acute, subacute and abortive. 

 It is possible to observe all of these forms in a single outbreak, as the sudden- 

 ness of the onset is apparently regulated by the amount of the poison laden 

 food which the animal has ingested. 



The acute type is characterized by the abruptness of its appearance, and the 

 grave general disturbances which immediately manifest themselves. There is 

 sometimes violent trembling and twitching of the muscles over the entire body, 

 but most commonly the acute form is ushered in by stupor. 



There is manifested a weak, staggering gait and the pharynx is either 

 partially or completely paralyzed. The tongue may also be partially paralyzed 

 and protrude from the mouth, and saliva falls in strings from the lips. The 

 pupil is dilated and the conjunctiva is, as a rule, highly congested. The pulse 

 is variable and may be very rapid and hard, or scarcely perceptible; the respira- 

 tion is hurried and jerky. The temperature may be slightly elevated, but is 

 most frequently subnormal. Intestines and bladder are paralyzed. 



In this form there may be slight muscular rigidity affecting the muscles 

 of the back, neck and jaws, although in many cases this symptom never mani- 

 fests itself. There is no rigidity of the ocular muscles. The animal soon 

 becomes so weak that he is no longer able to support himself and falls. Delirium 

 may manifest itself, in which the patient may perform a series of movements as 

 if trotting, or become so violent as to do himself serious injury, but most 

 often coma and complete paralysis supervene and death results in from four 

 hours to two days from the commencement of the attack. 



The subacute form is much the same as the preceding, except that it 

 developes more slowly and the symptoms are not so violent. It is first noticed 

 by a slowness in mastication and a difficulty in swallowing. A further indication 

 of approaching paralysis is seen in the frequent knuckling and the loss of 

 control over the tail. The temperature is subnormal and the pulse and respira- 

 tion are but slightly altered. The bowels and bladder are inactive and it is 

 seldom that voidance of urine and faeces occurs voluntarily. There is but 

 slight rigidity of the muscles if indeed there is any, and no evidence of pain is 

 apparent. These symptoms may last two or three days, when gradual improve- 

 ment takes place, or the paralysis becomes more complete, the general weakness 

 more marked, paroxyms of delirium develop, with inability to stand, breathing 

 becomes more labored, coma comes on and death results apparently without a 

 struggle. This form lasts from six days to two weeks. 



In the abortive form there are no well marked constitutional symptoms. 

 The appetite may be somewhat lessened, the ability to swallow slightly impaired, 

 and the animal's movements a little uncertain, but no very noticeable symptoms 

 appear to attract the attention. Improvement usually takes place on the third 

 or fourth day, and recovery is the usual result. 



Lesions. As a rule, post-mortem examination reveals no naked eye 

 changes in the tissues of animals dead of forage poisoning. There 



