32 HEALTH AND DISEASE 



Causes. — As influenza aii'ects a considerable number of animals which 

 are associated together in large establishments, the idea naturally arose 

 that the disease was spread by contagion. In opposition to this theory 

 there is the evidence that one case may be followed by another at the 

 other end of a large stable. In other instances a large number of animals 

 are attacked simultaneously. The disease also appears in certain localities, 

 in which it rages for a time and then rapidly ceases without any apparent 

 reason. In favour of the contagion theory it is urged that the introduction 

 of a sick horse into a healthy stable is followed by the propagation of 

 the disease, and that the introduction of horses into infected stables has, 

 at least in many instances, been followed by an outbreak of the malady. 

 It is undoubtedly expedient in practice to treat the disease as one of 

 the contagia. 



Symptoms. — Inriuenza is distinguished from common catarrh by the 

 very marked depression and weakness which attend the early stages. The 

 appetite is impaired, the temperature rises, the pulse gradually increases 

 in frequency, and the depression becomes more pronounced as the disease 

 advances. Swelling of the eyelids and redness of the mucous membrane 

 are also observed, and sometimes the swelling extends to the limbs, or 

 maybe the head. Discharge from the nostrils may, or, as in some cases, 

 may not, be present. Muscular pain and weakness is shown by the feeble 

 gait and the constant change of posture and resting of first one limb and 

 then another. 



In other cases the disease appears to be concentrated in the digestive 

 system, affecting the liver chiefly, when the membranes of the eyes and 

 nose become yellow, the faeces hard and coated with a glairy mucus. 

 In other instances the respiratory organs seem to suffer most, and some 

 of the worst cases terminate in a gangienous pneumonia. 



Results. — Influenza is not, under ordinary circumstances, a fatal 

 disease; the mortality has been stated by different authorities to amount 

 to 3, 4, 9, and 10 per cent. In the outbreak which occurred in the States 

 in 1872 the mortality among 30,000 horses was 7 per cent. The average 

 mortality from the disease is stated to' be from 1 to 4 per cent. 



Treatment. — The great variation in the mortality may be put down 

 to the difference in the surroundings of the sick animal. In ordinary 

 cases authorities allow that medicines are of little value, and careful 

 arrangement of the diet, disinfection and ventilation of stables, and a 

 general attention to sanitary arrangements are sufficient to combat the 

 disease. Avoidance of exposure to climatic changes and absolute rest are 

 essential. The disa,strous effect of continuing to keep horses at work after 

 the first indications of the disease are apparent has already been men- 



