MALARIAL FEVER IN HORSES. 473 



very wet seasons. It is the general opinion of those who have studied 

 the disease that it is caused by feeding on certain low, marshy pastures 

 and on hay that comes from such pastures. Whatever its origin, the 

 disease has spread on these pastures during the last few years. Horses 

 die from this disease on the Missouri river bottom and in the Elkhorn 

 valley and farther up in the western part of the state. In these districts 

 the loss is very great, especially in wet seasons, such as we have had in 

 the last few years. To the stockman the loss is very heavy, for when it 

 once makes its appearance on a ranch, it is very apt to recur, and carry 

 off every horse. Many ranchmen in these districts lost all of their horses 

 and were seriously crippled in finishing up their season's work, many 

 farmers losing from two to eight head of horses. This is the most serious 

 disease among horses that this state has been called upon to investigate. 



III. Symptoms. 



The disease usually starts in with a fever of the recurrent type. Fol- 

 lowing this is the symptom of weakness. The horses become tired easily. 

 They apparently have no life and perform their usual work with great 

 difficulty. The mucous membranes of the mouth and eyes become 

 very pale. After the animals have shown these symptoms for a few 

 days, one will notice a staggering gait. They become weak over the 

 loins, so that farmers suspect some kidney trouble. They drag their 

 legs. During these first symptoms the horses do not apparently lose 

 their appetite, eating ravenously, but growing thinner and weaker all 

 the time. The temperature becomes more elevated, running as high as 

 103° to 106°. The variation in temperature is one of the characteristic 

 symptoms. It may remain high for several days and then drop down, 

 only to rise again. In this condition of changing temperature the horses 

 become too weak to work. They lose flesh very rapidly and are usually 

 laid off from work. It may occur that the animal will improve for a 

 week or ten days, only to have another attack more severe than the first 

 one. Horses may have two or three attacks and death finally follows, 

 either from heart failure or from exhaustion. The ranchmen have 

 observed that when they feed their horses all they want while they are 

 sick with this disease, death is certain, but that if they feed them spar- 

 ingly they may recover, but usually have another attack. In the early 

 stages of the disease the pulse is always very rapid, while in the latter 

 stages it is very weak. Horses may linger with this disease for several 

 months. The writer has observed some to live three months. As a 

 rule, horses live from two to three weeks. It is only occasionally that 

 animals recover. Besides the above symptoms, there is a swelling of 

 the legs. This is a symptom that is not always observed, and then, 



