156 CLINICAL BACTERIOLOGY AND 



Young horses at an age when their dentition processes 

 are in full activity are congregated at fairs and sales, 

 come in contact with a focus of infection, and are suitable 

 prey for the many pathogenic bacteria to locate themselves 

 on the respiratory mucosae. During these eruptive dental 

 periods the natural protective elements of the system are 

 depleted, partly through malnutrition consequent upon 

 indigestion due to improper mastication of the food, the 

 phagocytes and the opsonins, etc., are below the normal 

 healthy standard, and in the case of the Irish hunter sent 

 over to England the nervous and systemic depression 

 following upon a long journey and sudden climatic changes 

 — not to speak of the ill effects of bad boat and rail 

 travelling — make these animals extremely susceptible to 

 all kinds of bacterial invasions in general, but pulmonary 

 in particular. 



Here, then, the immunizer has opportunities of rendering 

 good service to the seller and buyer of hunter and blood 

 stock. 



One cannot deny that our present knowledge will 

 not permit the use of a perfect prophylactic sero-vaccine 

 as long as the bacteriology of the diseases themselves, 

 which are productive of roaring and whistling, is in an 

 imperfect state. Nevertheless, this fact does not prevent 

 us from using the knowledge we do possess and turning 

 it to good account. 



Careful cultivation of the bacteria found in the discharges 

 of animals suffering from influenza or strangles, and also 

 from those obtained low down in the trachea and the 

 smaller bronchi, should be made. 



These also should be procured from animals located in 

 various centres in the kingdom. In this manner not only 

 would several strains of bacteria be formed, but varying 

 degrees of virulence would be obtained, and the mixing 

 of them together would give a polyvalent sero-vaccine. 

 This process, of course, would be too elaborate and ex- 

 pensive for individual effort to carry out, but it would be 



