INFECTIOUS DISEASES. 561 



the plexiform ganglion is next examined, and should negative results 

 still be obtained, the inoculation of rabbits is then made as a last 

 resort. It is indeed rare that positive results are obtained from the 

 latter method after the first two methods have been negative, but it 

 has occurred occasionally in cases in which the animal had been 

 killed in the early stages of the disease. 



Sym/ptoms.- — From the moment of inoculation by the bite of a 

 rabid dog or other rabid animal or by other means, a variable time 

 elapses before the development of any symptoms. This time may be 

 eight days or it may be several months; it is usually about four 

 weeks. The first symptom is an irritation of the original wound. 

 This wound, which may have healed completely, commences to itch 

 until the horse rubs or bites it into a new sore. The horse then be- 

 comes irritable and vicious, and it is especially susceptible to moving 

 objects, excessive light, noises, the entrance of an attendant, or any 

 other disturbance will cause the patient to be on the defensive. It 

 apparently sees imaginary objects; the slightest noise is .exaggerated 

 into threatening violence; the approach of an attendant or another 

 animal, especially a dog, is interpreted as an assault and the horse 

 will strike and bite. The violence on the part of the rabid horse 

 is not for a moment to be confounded with the fury of the same 

 animal suffering from meningitis or any other trouble of the brain. 

 But in rabies there is a volition, a premeditated method, in the at- 

 tacks which the animal will make, which is not found in the other 

 diseases.' Between the attacks of fury the animal may become calm 

 for a variable period. The writer attended a case in which, after a 

 violent attack of an hour, the horse was sufficiently calm to be walked 

 10 miles and only developed violence again an hour after being 

 placed in the new stable. In the period of fury the horse will bite 

 at the reopened original wound ; it will rear and attempt to break 

 its halter and fastenings ; it will bite at the woodwork and sur- 

 rounding objects in the stable. If the animal lives long enough it 

 shows paralytic symptoms and falls to the ground, unable to use 

 two or more of its extremities, but in the majority of cases in its 

 excesses of violence it does physical injury to itself. It breaks its 

 jaws in biting at the manger or fractures other bones in throwing 

 itself on the ground and dies of hemorrhage or internal injuries. 

 At times throughout the course of the disease there is an excessive 

 sensibility of the skin which, if irritated by the touch, will bring 

 on attacks of violence. Throughout the course of the disease the 

 animal may have appetite and desire water, but on attempting to 

 swallow has a spasm of the throat which renders the act impossible. 

 This latter condition, which is common in all rabid animals, has 

 given the disease the name of hydrophobia (fear of water). 



36444°— 16 36 



