DISEASES OF SWINE -197 



break in the skin may produce rabies. Hogs sometimes show a dis- 

 position to bite and may infect other animals. The average period 

 of incubation is from two to three weeks. 



Symptoms. Rabies in hogs is characterized by very much the 

 same train of symptoms as occurs in other animals. The' hog is very 

 restless and excitable, and if lying down or hidden in the litter may 

 jump up suddenly, squeal and run about as if pursued. They will 

 back up as closely as possible in the corner of the pen. The squealing 

 has a peculiar crying sound. They are very nervous and easily star- 

 tled and will break for a person or other stock. The eyes are at times 

 fixed or may roll about,. and there is an abundant secretion of saliva. 

 Frequently they will gnaw the boards of the pen and make desperate 

 efforts to get out. They will bite other animals and swallow indiges- 

 tible substances. Swallowing is difficult on account of the early pa- 

 ralysis of the muscles of deglutition. The duration of the disease is 

 short. Paralysis occurs early and the hog lies or hides in the litter 

 most of the time and pays no attention to its surroundings. It be- 

 comes weak and emaciated and dies in a few days. 



Lesions. The changes in the tissues are neither constant nor 

 specific. The most constant lesions are microscopic in character and 

 are found in the brain. A congested condition of the mucous mem- 

 brane lining the pharynx, larynx and stomach, enlargement of the 

 spleen and hyperemia (congested condition) of the brain are some- 

 times seen. Frequently the stomach contains foreign matter, such 

 as stones, straw, pieces of wood, etc. 



Treatment. The treatment of hogs in any way is not prac- 

 tical. As soon as a hog develops rabies, it should be destroyed or 

 isolated in order to prevent its spreading the disease. (Ind. B. 100). 



TETANUS, OR LOCKJAW. 



Causes. Tetanus is caused by a specific germ, Bacillus te- 

 tani. This organism exists in most soils but is more common in 

 some localities than in others. In warm climates it is more abundant 

 than in cold, and dirt rich in organic matter seems to be the favor- 

 ite place for it. It enters the body by way of a wound, sometimes so 

 slight as to escape observation. It may follow as a result of castra- 

 tion and any deep or punctured wound that is not open to the air is 

 a suitable place for its development. Tetanus germs differ from 

 some of the other forms in that they do not enter the circulation 

 and become distributed to different parts of the body, but remain 

 at the point of infection. There they manufacture poisons (toxines 

 and ptomaines) that arc taken up by the circulation and have an ac- 

 tion on the nervous system similar to strychnine. 



Symptoms. The acute form of the disease is usually seen in 

 hogs. The spasms begin with the muscles of the jaws and face, and 

 spread rapidly to other parts of the body, involving especially the 

 back and limbs. Shortly, the hog becomes unable to stand, falls 

 on its side and can not get up. It remains in this position with the 

 limbs extended and rigid. The respirations are labored; frothing 

 at the mouth is noticed and convulsions may occur. The protrusion 



