196 VETERINARY STUDIES 



disease, applies to lungs as well as to muscles, and must always 

 hold true. Domestic animals cannot remain generation after 

 generation healthy and vigorous without a reasonable amount 

 of exercise, sunshine, and fresh air. Nature's laws cannot be 

 violated without paying an inevitable penalty. 



It is unwise to buy cattle for breeding purposes without 

 knowing that they are free from tuberculosis and this implies 

 first of all dealing with an honest breeder. Tuberculin tests 

 of cattle from an unreliable breeder or jobber are of little value. 

 All sires— this is especially true of cattle — should have abun- 

 dant exercise in open yards or on treadmills, or be driven or 

 worked. Ventilation must be thorough, and barns should be 

 constructed with a view to allowing the entrance of abundant 

 sunshine. Sunshine kills germs. 



The student must not gather from this statement that a 

 herd may not be badly diseased in an ideal stable if tuber- 

 culosis spreaders are put into it, nor that good sanitary condi- 

 tions will clean up a diseased herd. There is abundant proof 

 to the contrary. Such stables are safer and spread of infectious 

 disease must be slower than where conditions are bad. 



Summary. — Do not found a herd with tuberculous stock. Do 

 not introduce the disease while trying to improve a herd. Do 

 not allow suspicious animals in stable with healthy ones. Avoid 

 close confinement. Allow plenty of fresh air, exercise, and 

 sunshine to breeding stock. 



All breeding cattle should be bought under tuberculin test, 

 from a sound herd and a reliable breeder. Do not buy even on 

 test from a tuberculous herd, or from a herd that has recently 

 been badly affected. 



Disposition of tuberculous cattle. — Abundant experiments 

 have demonstrated that healthy calves can be raised from tuber- 

 culous cows, and from tuberculous sires. In case of unusual 

 value or breeding, it is sometimes practical to free a herd from 

 tuberculosis by breeding out the disease, instead of by immedi- 

 ately killing all diseased animals. Animals which the owner 

 does not think it advisable to keep in quarantine, at an increased 

 expenditure of time and money, should be slaughtered. It is 

 generally recognized that tuberculous animals should be slaugh- 

 tered under inspection and many carcasses should be passed as 

 fit for food purposes. 



Tuberculous cattle retained for breeding must be kept in a 



