532 PRINCIPLES OF VETERINARY SURGERi' 



affected, it would be an error to erect this fact as an absolute 

 law, as observations of melanosis among animals with dark 

 coats are not rare. They have been observed in roans, 

 blacks, dark bays and chestnuts. Although the common 

 breeds are most susceptible, the disease has been seen in 

 thoroughbreds. 



The heredity of melanosis is certain. Gohier reports the 

 following facts: A stallion with white hair was used from 

 two to four years, and then invalided on account of melan- 

 osis. He had begotten a great number of both males and fe- 

 males, which all inherited his coat and developed the disease 

 in adult life. Even those born while their sire was still a 

 colt, and before the disease had appeared, were not exempt. 

 Schults and Raabe are also of the opinion that melanosis 

 is congenital. 



Age has an uncjuestionable influence on the appearance 

 of the tumors. True, they have been seen in young horses 

 but only in a few cases and always in small forms. They are 

 generally found in animals from six to twelve years old and 

 chiefly after the age of ten. From the twelfth to the fifteenth 

 years, generalization takes place. Sex has no influence. It 

 has been even sought to show that contagion plays a role in 

 the matter, but Gohier, and others failed to reproduce it by 

 inoculation. Virchow had only negative results in introduc- 

 ing human melanosis into dogs and rabbits. Intravenous in- 

 jections produced pulmonary emboli, in the center of which 

 were found melanic substance without modifrcation. How- 

 ever, according to Baillere, Goujon and Klenke, melanosis 

 may be transferred to the horse and dog by inoculation. Ac- 

 cording to 3ard, melanosis must be a parasitic disease with 

 the role of the microbe to be determined. He based his con- 

 clusions on extended arguments that deserve no considera- 

 tion, and finally abandoned the hypothesis. 



DEPOSIT OF MELANOTIC SUBSTANCE.— A search 



