BOTULISM IN CATTLE 71 



yet in the chronic disease the appetite as well as organs of deglu- 

 tition appear quite normal. The body temperature remains 

 essentially unchanged, with slight fluctuations upward which 

 are of short duration unless associated with secondary infection. 

 Subnormal temperature and obstinate constipation are invari- 

 ably present. 



SUSCEPTIBILITY 



Preliminary observations indicate that cattle between the 

 ages of six months and two years are most susceptible, while 

 older annuals may also be affected. The mortality varies 

 between 2 and 10 per cent though in extreme outbreaks a loss of 

 30 to 70 per cent or higher may occur. From observations it 

 would appear that some cattle have, or acquire, an immunity 

 to certain types of poisonous substances in feed, yet the natural 

 resistance possessed by cattle of all ages to the type of intoxica- 

 tion under consideration is not always sufficient to protect 

 against more or less serious constitutional disturbances. In 

 more resistant animals death is not induced, yet the growth 

 and development of the affected animal may be temporarily or 

 permanently impaired. The mortality of the disease in many 

 outbreaks may thus be secondary to the loss sustained by failure 

 of the animals to increase in weight, by the decrease in milk 

 flow in dairy cattle, or the loss of the feed in case the contami- 

 nated ration can be detected. Moreover it is believed that 

 symptoms of B. botulinus intoxication in resistant cattle may 

 thus be transitory and of an indefinite character, and that bovine 

 forage poisoning may even prevail unrecognized as a distinct 

 disease, manifested only by unthrift and malnutrition. In the 

 light of recent observations the writers have probably failed to 

 recognize the disease in cattle as a clinical entity in several out- 

 breaks during the period of 1912-1917. 



CAUSATIVE FACTOR RELATED TO RATIONS 



In clinical outbreaks of the above character, bacteriological 

 evidence has seldom been obtained to sustain or refute a pre- 

 sumptive diagnosis of a food or forage poisoning. As a matter 



