JOINT ILL 87 



commonly associated, and, according to some authors, 

 the colon bacilli prepare the field for the pathogenic 

 bipolar bacilli, the latter giving rise to the septicemic 

 infection. 



Prophylaxis. — There are various brands of serum 

 on the market, all lauded as giving protection against 

 joint ill. When we consider the variety of organisms 

 responsible for the production of the disease, we can 

 easily imagine why such futile results are obtained in 

 practice by the use of a serum prepared from one 

 particular organism in giving protection against joint 

 ill. A serum, to be of any use, should be polyvalent — 

 that is, prepared from all the organisms that are 

 found responsible for the production of the disease. 

 In practice such a serum is found to be poor in anti- 

 bodies specific for each organism from which it is 

 prepared. However, the use of a polyvalent serum 

 offers a better chance of affording protection, especi- 

 ally if given immediately after birth, than any of the 

 monovalent serums. 



Vaccines have also been advocated as giving 

 protection, and lately McFadyean has advised the use 

 of a polyvalent vaccine prepared at his Kesearch 

 Institute as a preventative. It may be used in the 

 following ways : 



1. To vaccinate the mares before foaling. 



2. For vaccination of foals after birth. 



3. For treatment of foals attacked with the disease. 

 In considering the use of vaccine, we must re- 

 member that in most cases it takes from six to twelve 



