No. 7. DEPARTMENT OF AGRICULTURE. 643 



deafness, stenosis light bone, contracted feet, faulty attitude of limbs, 

 low back, weak coupling, cryptorchidism, springhalt, shivers, and 

 crampiness. 



In looking over this list many defects will be seen that may be 

 produced by accident. While it is not difficult for a person of exper- 

 ience to recognize some of them, it is sometimes impossible to dis 

 cover the true cause. 



The subject of heredity is very complicated and it is not to be ex- 

 pected that the present generation will be able to solve all its mys- 

 teries. Many horses are sound from a breeding point of view that are 

 not even serviceably sound for saddle or harness purposes. Con- 

 ditions that are caused by accidents, over-work, bad care, and some 

 acute diseases, should not ordinarily condemn animals for breeding 

 purposes, yet they may render them practically worthless for work. 



Let us revieAv the etiology of the listed abnormal conditions, and 

 see what part heredity plays in producing them. 



Vicious habits cover such defects as kicking, biting, running away, 

 cribbing, weaving, balking, etc. Most authorities agree that traits 

 of character are transmitted, yet it is known that in a large majority 

 of cases such defects are due to bad handling, and with proper treat- 

 ment many horses with decidedly vicious habits will become the most 

 amiable. Nature has apparently done her part well, yet man's ig- 

 norance has made it appear a failure. 



Several breeders, as well as veterinarians, have seen cases where 

 such habits were transmitted and consequently believe that they 

 should receive serious consideration from a breeders' point of view. 

 Dr. John V. Newton cites the case of "Marcus Claudius," a draft 

 stallion that he owned. This horse had a mean disposition, and fifty 

 per cent, of his get were affected in the same way. 



From the evidence collected it would appear that horses vicious by 

 nature should be excluded. 



In reference to blindness, two forms are questionable, viz : periodic 

 ophthalmia and cataract. These diseases are miich more prevalent 

 in some sections of country than in others. A few breeders, as well 

 as a number of the leading veterinarians expressed positive opinions 

 in reference to their being hereditary. In the Report of the Veterin- 

 ary Examination of Stallions by the Department of Agriculture in 

 Australia, cataract is listed as an hereditary unsoundness. In the 

 human family, cataract of childhood is looked upon as congenital, 

 while cataracts that develop after maturity are not so considered. 



Periodic ophthalmia is not seen in the human family and yet it is 

 practically the only recognized cause for cataract in horses. In 

 the great majority of cases periodic ophthalmia develops only after 

 maturity. Congenital cataract has been known in foals. 



Some of our text books, and many of the most thorough investi- 

 gators consider period opthalmia as infectious, and cite a number of 

 interesting cases as proof. It would appear that there is more reason 

 at present for excluding sires or dams afflicted with this disease on 

 account of its infectious nature than from an hereditary point of 

 view. 



Roaring and broken wind are listed as hereditary by English and 

 Australian authorities. None of the correspondents reported a case 

 where the trouble was believed to have been transmitted. Dr. George 

 White, of Nashville, Tenn., reports one sire and twenty-five dams 



