530 



On Mismanagement of Farm-Horses. 



inflammation of the delicate sensitive laminae of the foot. It may 

 be caused either by the unwonted stress which overwork imposes 

 directly upon these structures, or by derangement of the digestive 

 system and of the skin. Violent exertion frequently induces lami- 

 nitis, by increasing to excess the functions of the skin, and thus 

 rendering it unusually susceptible of the action of cold. From 

 the exhaustion of the system which usually obtains in such cases, 

 and from the undue elevation of the surface heat, the cold ope- 

 rates as a powerful sedative ; the blood leaves the surface and 

 collects round internal organs, and the secretion of the skin is 

 arrested, and all its functions are impaired. The laminae, how- 

 ever, are merely skin modified to serve a special end ; they are 

 continuous with it, and are affected by the same agencies which 

 influence it. On account, however, of their extreme vascularity 

 and sensitiveness, they are far more speedily and intensely acted 

 on by any cause of disease, and hence these laminae are often 

 excited to acute inflammation by causes inadequate to inflame 

 other portions of the skin. Such is the manner in which we 

 believe most cases of laminitis to be produced by the influence of 

 overwork. 



3. Insufficient shelter. — In a climate such as ours, and in the 

 absence of epidemics and epizootics, the great proportion of 

 disease, both in man and the lower animals, is traceable to vari- 

 able or low temperature. In man a direct relation is observable 

 between temperature and the prevalence of disease. Tempe- 

 rature," says Dr. Guy, " is beyond all doubt the most influential 

 cause of disease." * The tables of the Registrar-General also 

 establish the fact that a cold season or winter is always accom- 

 panied by a high rate of mortality.f 



Insufficient shelter acts injuriously on all animals, chiefly by 

 exposing them to sudden changes of temperature and to the influ- 

 ence of excessive cold, winds, rain, and storms. 



Animals in good health and abundantly supplied with food do 

 not suff"er much inconvenience even from very great cold, if unac- 

 companied by moisture. Of this we have sufficient evidence in 

 the fact that horses, as well as other animals, living at high alti- 

 tudes, and in climates much colder than ours, enjoy unimpaired 

 good health. In such animals, however, there is an unusual 

 expenditure of heat, in consequence of the contact of the cold air, 

 the greater evaporation and radiation from the surface of the 

 body, and the increased density of the inspired air. To compen- 

 sate for this unusual loss, a larger supply of food is necessary than 

 for animals surrounded by and breathing a warmer air. In short, 



* Statistical Journal, vol. viii.— Paper on the Influence of Seasons on Sickness and 

 Mortality, p. 137, eijoassim. 



t Eighth Annual Report, p. xxxvii. ; Combe's Physiology of Digestion, p, 87. 



