10 July, 1919.] Hereditary Unsoundness in Horses 



419 



Nine grandsons of 21 were examined, and three, or 33.3 per cent., were 

 unsound, but as the sound members were all aged horses at time of 

 examination, the factor for unsoundness is not strongly developed, if at 

 all, and the family may be regarded as a sound one, with unsoundness 

 introduced from mares. The pedigrees of the unsound members are 

 not clear, but — 



21.11 appears to be from a mare by a brother of 11.21, 

 21.101 was from a mare by 7.4923, a doubtful family. 

 21.16 was by an unrecorded son of 9.5, a doubtful family. 



The relationship of this family to Family 1 has already been pointed 

 out, and frequent reference has been made to members of it owing to 

 unsoimdness through the female side of pedigrees. Of the progeny of 22 

 28.5 per cent, of those examined showed unsoundness. Particularly 

 is this seen in the great-grandsons, four out of five being defective. 

 Recognising the connexion with Family 1, there is every reason to 

 believe that unsoundness predominates in the early branches, and is 

 becoming a diminishing factor in the later generations. 



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