148 VETERINARY STUDIES 



disease, it will generally prove good management to nurse the 

 flock through until spring, then depend on getting the sheep 

 into shape for market during the summer, and sell out for 

 butcher stock in the early fall. Such sheep are entirely fit for 

 food purposes when in good flesh. 



Prevention. — New sheep should be purchased from a flock 

 that has been thrifty during two previous late winters and early 

 springs, and they should be kept for two seasons on some other 

 pasture than the one previously used on the infected farm. It 

 will be better still if the flock can be kept part of the season on 

 pasture and part of the season on plowed crops; e.g., rape, 

 sorghum, field peas, or meadow land that has not recently been 

 used for sheep pasture. The new flock must not be allowed to 

 drink from any pond or sluggish stream that has received drain- 

 age from the infested pasture or barnyard. 



With a view to preventing this and other parasitic diseases, 

 the flock should not be kept too long on one pasture, but should 

 be moved from pasture to pasture; and from pasture to stubble 

 fields, cut-over meadow, rape, etc. Sluggish streams and ponds 

 should always be regarded with suspicion. 



It is possible to practically rid a flock from the nodule disease 

 by following this course of shifting the flock about for several 

 years, plowing up pastures occasionally, and using plowed 

 crops. The infectiousness of pastures has been shown by care- 

 ful experiment in which infected sheep were placed on small 

 pastures during a season and then during the next season sheep 

 were kept on this same pasture which were previously free from 

 nodule disease. Rapid infection of the second flock was secured 

 in this way. The disease spreads from ewes to pasture and from 

 pasture to lamb. 



