CHAPTER XXIX 



INFECTIOUS DISEASES OF THE HORSE 



Strangles. Distemper. — This is an acute infectious disease 

 associated with a catarrhal condition of the air-passages and 

 suppuration of the lymphatic glands in the region of the throat. 

 Colts are the most susceptible to the disease. One attack renders 

 the animal immune against a second attack of the disease, but the 

 immunity is not always permanent. 



The specific cause. Streptococcus equi (Fig. 113), was dis- 

 covered by Schutz in 1888. Strangles is commonly spread by 

 exposing susceptible animals to dis- 

 eased animals, either by direct contact, 

 or by exposing them to the infection in 

 the stable and allowing them to drink 

 or eat food from watering and feeding 

 troughs on premises where the disease 

 exists. The j)redisposing causes are 

 cold and sudden changes in the weather. 

 For this reason the disease is most 

 prevalent during the late winter and 

 early spring. 



The period of incuhation varies, usually from four to eight 

 days. 



The symptoms at the beginning of the attack are a feverish 

 condition and partial loss of appetite. The visible mucous 

 membranes are red and dry. This is followed by watery nasal 

 secretions that become heavy and purulent within a few days. 

 The inflammation may extend to the larynx and pharynx. 



The glands in the region of the jaw become hot, swollen and 

 painful, and the animal may be unable to eat or drink. The 

 swelling and inflammation of the throat, and the heavy, pus-like 



309 



Fig. 113. — Streptococcus of 



strangles. 



