136 AGRICULTURAL RESEARCH AND THE FARMER : 



the limbs are visibly swollen and inflamed. In many cases the 

 swelhng of the joints is preceded or accompanied by disease of 

 the navel, and the term " navel ill " is therefore almost synony- 

 mous with joint-ill. The disease is a common one, and since 

 it has a high mortality it is a source of annucd loss and dis- 

 appointment to breeders, especially to those who possess valuable 

 animals. The disease of the navel is usually of the nature of 

 an abscess, and an examination of the pus which forms there 

 often shows bacteria of the form known as streptococci. Within 

 recent years anti-streptococcus serum — that is, a serum drawn 

 from horses who have been injected with increasingly large 

 doses of streptococci and thereby developed immunity from the 

 disease — has been largely used in the treatment of joint-ill, and 

 its injection into healthy foals has been recommended as a means 

 of prevention. In the belief that previous infection of the mare 

 is responsible for many cases of joint-ill, it has also been held 

 that the disease may be prevented by treating mares with serum 

 or vaccine shortly before foaling. Experiments in connection 

 with joint-ill have been in progress at the Institute since 1917, 

 and for the first three years an endeavour was made to ascertain 

 whether anti-streptococcus serum was actually effective for pre- 

 vention or cure. The results of the work indicated that the serum 

 had failed to exert any appreciable influence on the death rate. 

 Further, the histories of nearly 700 cases of joint-ill showed that 

 some of the views hitherto current regarding the disease were 

 erroneous. Except possibly in an insignificant proportion of 

 cases, the disease is not derived from the mare; the foals as a 

 rule are born healthy, and the disease arises from the contamina- 

 tion of the navel with what may be called dirt bacteria. The 

 bacteria known as streptococci are the cause of only about 50 % 

 of the cases, and three or four other species of organisms are 

 accountable for the remainder. 



During 1920, therefore, the Institute abandoned serum 

 treatment, and resolved to issue vaccine prepared from strepto- 

 cocci. The vaccine is composed of the artificially cultivated 

 organisms killed by heat. Streptococcus vaccine has for several 

 years been widely advertised, and probably to a considerable 

 extent sold, as a remedy of great value against joint-ill, but 

 no statistics of any value have ever been published to show what 

 effect such treatment has either for the prevention or the cure 

 of the disease. During the last foaling season the Institute 

 sent out over 2,000 doses of vaccine prepared from streptococci 

 isolated from actual cases of joint-ill. Some of this vaccine 

 was employed for the treatment of mares before foaling, and the 

 remainder for the treatment of foals immediately after birth or 



