52 HEALTH AND DISEASE 



the diseased structures are not submitted to any critical examination for 

 the detection of the tubercle bacilli. 



In the event of tubercle being detected, on post-mortem examination of 

 one horse of a number kept in the same stable, the tuberculin test might 

 be applied experimentally. 



DOURINE (MALADIE DU COIT) 



This is a specific contagious disease which, like rabies, is communicated 

 only by contact of the virus with an abraded or broken surface. Whether 

 occurring in the male or female horse, it primarily affects the external 

 organs of reproduction, viz. the penis in the male and the vaginal passage 

 in the femal6. (See Plate XXXV.) 



In consequence of this, and the frequency with which it is transmitted 

 from one to the other during the act of copulation, it has been distin- 

 guished as " Maladie du Coit", or Covering Disease. Some distinguished 

 veterinary authorities in France and elsewhere have regarded it as identical 

 with syphilis of man, but there is no real evidence upon which to base 

 such a conclusion. It must be admitted that there are in both certain 

 common features, as there are in other specific affections, but the points 

 of divergence are too many and too decided to allow us to assent to the 

 doctrine of unity, for which Bouley, Trasbot, and some other Continental 

 pathologists are responsible. For the same reasons we dissent from the 

 view that it is identical with glanders. 



Dourine has appeared as an epizootic in Russia, France, Austria, Switzer- 

 land, and other parts of the Continent from time to time during the past 

 century, with disastrous results to the breeding-stock of those countries, but 

 we are not aware of its having occurred in any part of Great Britain. 



Origin. — The cause of this disease is the entrance into the blood of a 

 .species of protozoa — the Trypanosoma equipedum. This is a unicellular 

 organism having a fiagellum by which it is capable of considerable activity. 

 So far as at present known it is the only trypanosoma which is not trans- 

 mitted by a biting insect. The common mode of access of the virus is 

 through the medium of the external genital organs during the act of 

 copulation. The spread of the malady is effected more especially by 

 stallions when going from mare to mare during the breeding season. 



It has been induced experimentally, by Nocard, with matter from a 

 diseased centre in the spinal cord, and previously, by Hertiug, with dis- 

 charges from the vaginal mucous membrane. 



Symptoms. — The period of incubation is said to extend from eight 

 to twenty-eight days. At the expiration of the term a discharge issues 



