DOUKINE. 511 



the former being more common than the latter. Mares are more 

 liable to acute dourine than stallions. 



GEOGRAPHICAL DISTRIBUTION.— It was first observed in 

 Germany by Ammon in 1796, and has since that time spread to a 

 greater or less extent, through Germany, Austria, Russia, Italy, 

 France, Algiers, Syria, and America. As far as I have been able 

 to learn, it is unknown in Great Britain, Ireland, the Indian 

 Empire, China, and Australasia. Roll states that it is not met 

 with in Belgium. " Dourine appears on rare occasions in the 

 South of France, and is frequently met with in Spain and Algeria " 

 (Cagny and Gohert). 



MODE OF PROPAGATION.— It is a purely contagious disease ; 

 that is, it can be transmitted only by contact, and under all ordi- 

 nary circumstances, only during the act of coition, from stallion 

 to mare, and vice versa. The inoculation of fresh blood is the 

 most effective means of transmitting dourine. 



NATURE OF THE DISEASE.— In 1896, Dr. Rouget showed that 

 dourine is a true infective disease caused by a trypanosoma which 

 is closely akin to the parasite of surra (p. 457). 



PERIOD OF INCUBATION.— " On account of the chronic 

 course of the disease, the infective matter may remain apparently 

 latent in the system of a horse for a very long time, even for 

 more than a year" (Friedherger and FrohnerJ. 



DURATION AND CHANCES OF RECOVERY.—" The duration 

 of the attack may vaiy from eight months to one or two years, 

 and recoveiy is rare. In male and female donkeys, the disease 

 runs a very slow course, and is seldom fatal " (Cagny and 

 Gohert). Not unfrequently an apparent recoveiy is followed by 

 a relapse and death. 



CHANCES OF RECOVERY.— The mortality is at least 70 per 

 cent. ; and is greater in stallions than in mares. 



SYMPTOMS. — The symptoms of chronic dourine may be divided 

 into local and general; and the attack, into three periods. 



First period. — From eleven to twenty days after the stallion 

 has covered an infected mare, the first symptom to appear, is 

 swelling of the penis and particularly of the head of the 

 penis, which, on this account, cannot in some cases be 

 drawn back into the sheath: a complication that may also 

 happen after castration. The swelling spreads from the penis 



