346 ACUTE GENERAL INFECTIOUS DISEASES 



develops. In mares the vulva may swell and a mucopurulent 

 discharge be present. Pregnant mares often abort. In 

 stallions the scrotum is often enlarged and orchitis may be a 

 symptom. 



Skin. — While there is generally an edema of the hind limbs 

 present in influenza, in some outbreaks it is much more pro- 

 nounced than in others. With increased heart weakness, 

 edemas appear in pendent portions of the body (under chest, 

 abdomen, udder or scrotum). Occasional cases of tendo- 

 vaginitis, particularly of the flexor tendons, are noted, and 

 once in a while laminitis occurs. The patients usually lose 

 flesh rapidly, and become very weak and debilitated. 



A very dangerous complication is pneumonia or pleuro- 

 pneumonia, which usually assumes the catarrhal form, and 

 may be hemorrhagic in character. Such cases seriously dis- 

 tm-b the functions of the heart and kidneys, and often lead to 

 death. 



Diagnosis.; — The diagnosis is usually not difKcult. The 

 rapid spread of the disease from animal to animal, the icteric 

 mucous membranes, conjunctivitis and skin edemas difl^eren- 

 tiate it from other diseases attended by high fever. When 

 these symptoms are absent the highly infectious character of 

 the disease, as evidenced by the rapid spread, is significant. 



While a differentiation between influenza and infectious 

 pneumonia of the horse can usually be made if the course of 

 the disease can be studied, at first visit it may be very diffi- 

 cult. The prodromal symptoms of the two diseases are very 

 similar. The high initial fever, the swelling and icteric dis- 

 coloration of the conjunctiva, the contagiousness and the 

 inflammatory swellings in the subcutis and tendon sheaths are 

 common to both. Usually, however, on the second or 

 third day in infectious pneumonia, tangible symptoms of 

 pneumonia develop; in influenza pneumonia occurs as a 

 complication, and usually much later in the course of the 

 disease. Furthermore, influenza is more apt to attack the 

 intestinal tract early. A differentiation between influenza 

 and infectious anemia would become important only in dis- 

 tricts in which the latter disease exists. In infectious anemia 

 no catarrhal symptoms develop, the mucous membranes show 



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