8 Veterinary Medicine. 



ing disease like measles, cowpox or anthrax is rarely attacked a 

 second time. Again predisposition may be due to environment 

 as when we find herds in damp and exposed localities obnoxious 

 to rheumatism, and horses in dark mines exposed to specific oph- 

 thalmia. It may be the result of food as when the flesh-fed fox 

 or rat resists anthrax and the farina-fed one falls a ready victim. 

 Age may predispose, early youth being remarkably susceptible to 

 parasitism and bacteridian infection, and old age to fractures and 

 degenerations. Sex is inevitably a cause of limitation of disease 

 as the females and males can only suffer from disease of their 

 respective sexual organs. Again of diseases common to both 

 sexes certain nervous and digestive disorders are common in con- 

 nection with gestation, and certain calculous diseases in connec- 

 tion with the long and narrow urethra of the male. Tempera- 

 ment has a marked influence, thus the sanguineus or nervous 

 race-horse or hound shows a marked predisposition to diseases of 

 the heart, lungs and brain, and to a sthenic type of inflammation 

 and fever, while the heavy lymphatic draught-horse has a pro- 

 clivity to diseases of the lymphatics and skin. Idiosyncrasy is 

 closely allied to temperament, but the condition may be less 

 manifest, and the peculiarity is only recognized by the results, as 

 when a man is poisoned by sound fish or raspberries. Debility 

 whether from deficiency or poor quality of food, on the one hand, 

 or from overwork, filth, dampness or disease on the other must 

 be looked upon as strongly predisposing to certain diseases, such 

 as tuberculosis and glanders. Plethora which charges the blood 

 and tissues in a different way with effete organic products, lays 

 the system especially open to certain diseases like black quarter 

 in young cattle, and parturition fever in cows. Disease of one 

 organ often predisposes another organ through interdependence 

 of function, as when torpid or congested liver leads to portal and 

 intestinal congestion, diseased teeth to digestive disorder, im- 

 perfect haematosis to kidney trouble ; in other cases blood clots or 

 bacteria from one pathological centre may be arrested in the blood 

 vessels of a distant organ and start new foci of disease (embol- 

 ism, metastasis) ; in still other cases the impairment of the 

 healthy function in one organ acts injuriously on another, as 

 when emphysema or other disease of the lungs forces the blood 

 back upon the heart causing dilation with atrophy of the walls. 



