INFLUENZA. 463 



pink-eye is but an aggrayated variety of the catarrhal form. For 

 convenience sake, I shall adopt the latter view. This peculiar 

 colour of the inside of the eyelids was a marked symptom of the 

 great epizootics which appeared during 1877 and 1882-3 in Eng- 

 land and Scotland. In the bowel form, which is the gravest of all, 

 the mucous membrane of the eyelids is of a brick or orange red. 

 Hence, it would appear that the colour of the mucous membrane 

 is regulated rather by the severity of the attack, than by any dif- 

 ference in the exciting cause of the disease. 



DISTRIBUTION. — Influenza is well known throughout the 

 United Kingdom, North America, the Continent, and, to a less 

 extent, in India. 



DURATION. — ^The acute stage usually runs its course in less than 

 a week. When there are no complications, recovery is generally 

 complete within a fortnight. 



IMMUNITY acquired from one attack may last from one to six 

 years (Cadiot and Ries). 



The MORTALITY among properly treated cases, will not exceed 

 3 per cent, as a rule. 



SYMPTOMS. — The distinguishing characteristics of influenza are 

 the suddenness of its attack, its widely-distributed nature, and the 

 debility, depression, and rise in internal temperature (to 104°, or 

 even to 105° F.) which accompany its onset. Simple catarrhal 

 influenza, besides these characteristics, has little to distinguish it 

 from nasal catarrh (p. 369). In ordinary pink-eye, catarrhal 

 symptoms are, usually, not well marked. An attack is not unfre- 

 quently preceded by colicky pains. There is considerable rise of 

 the internal temperature, which may be observed, at least, twenty- 

 fouT hours before the manifestation of the symptoms ; great de- 

 bility ; stiffness of the limbs and body at first ; weak, frequent 

 pulse ; and a pink appearance of the inside of the eyelids. There 

 is great dulness ; in fact, the animal is in a more or less uncon- 

 scious state. As a rule, the eyelids swell, and tears flow from the 

 eyes. Constipation is generally present ; although those cases in 

 which spontaneous diarrhoea or profuse staling occurs, recover far 

 more rapidly than the others. The stiffness of the limbs is usually 

 followed by swelling of those parts, and consequent disappearance 

 of pain. Sometimes, there is great lameness as if from inflamma- 

 tion of the feet (laminitis, p. 184). Occasionally, cough and sore- 

 ness of the throat are present. Symptoms of inflammation of 

 the lungs may also appear. 



