INFLUENZA IN HORSES. 210 



ter — the thermometer sometimes marking 8° below zero — yet the losses 

 in the country districts are estimated at 1 in 300. 



Overcrowding, with its. concomitants of hot, damp, vitiated air, has 

 unquestionably been a main cause of the severity and complications of 

 the disease in the large cities, the pneumonias, pleurisies, i>urpura-hfem- 

 orrhagicas, &c., but the malignancy of all specific febrile diseases, occur- 

 ring with such unwholesome surroundings, forbids that we should 

 attach any importance to these in estimating the causes of tliis partic- 

 ular disorder. Influenza in man shows a similar malignancy and 

 fatality in unwholesome localities, and in overcrowded portions of cities 

 where hygienic arrangements are imperfect. The observations of Pear- 

 son, Parkes, Baker, Gray, and the English registrar-general have suf- 

 ficiently established this fact. And equine influenza, when more circum- 

 scribed than at present, has often confined its ravages to exposed 

 stables, open and swept by draughts of cold air, or close and without 

 ventilation, light or drainage, but with an impure, damp, and stifling 

 atmosphere. Yet such conditions can only retard or prevent the elimi- 

 nation of effete matter from the system, favor the introduction of the 

 deleterious products of decomposition in animal and vegetable matters, 

 saturate the blood with impurities, and by impairing or suspending 

 nutrition and other important functions lay the system open to the 

 access of disease. But while they facilitate the development and 

 increase the severity of all zymotic maladies, they do not determine 

 which specific affection shall be developed in a particular case. That 

 is determined by the prevalence of influenza, glanders, or other specific 

 disorder in the locality at the time. And it is noticeable in this con- 

 nection that the equine influenza of 1872 did not originate in a crowded 

 city, as is generally supposed. 



iSiiddcii clmnges of weather and temperature. — Nasal and bronchial ca- 

 tarrhs often prevail extensively among horses, as among men, in con- 

 nection with sudden and extreme variations of temiicrature, and espe- 

 cially in spring and autumn. These are liable to be confounded with 

 influenza, and hence the idea that this disease is but a simple result of 

 such climatic vicissitudes. In the case of the horse the changeable sea- 

 sons are often aggravated by the weakness and susceptibility of the sys- 

 tem in connection with the spring and autumn changes of coat, the 

 transition from the hot stable to the cool field, or from the clear atmo- 

 sphere of the pasture to the close, hot, impure air of the stable, the 

 changes from green to dry food, or vice versa, and tlie substitution of 

 work for idleness, or the reverse. That the etlect of sudden changes of 

 temperature is very severe on the animal system which has not become 

 habituated to the new condition of life by a gradual transition from one 

 to the other, is well shown in W. Edwards's experiments on cold-blooded 

 animals. Though' subjected to a very low temperature in winter the 

 heat of their bodies declined barely four-tenths of a degree, whereas ex- 

 posure to a cold temperature in summer insured a depression of body- 

 heat to the extent of 3° and even G° Cent. So it is with warm-blooded an- 

 imals transferred from a warm to a cold climate. The French cavalrj^ 

 horses, sent from the shores of the Mediterranean to the northern parts 

 of the country, suffer to a great extent from catarrhal and i^ulmonary 

 affections. But such catarrhal attacks do not spread as au epizootic, 

 nor extend from the newly-arrived horses to those which are permanent 

 residents. Catarrhal symptoms exist, indeed, but the contagium which 

 secures an extension and general i^revalence of the malady is wanting. 

 Such vicissitudes, therefore, operate like other unwholesome conditions 



