lo May, 1 910.] Hereditary Unsoundness in Horses. 



345 



with normal cartilage in between the summit anil base. I have one 

 specimen in which the sidebone had become detached from the wing of 

 the OS pedis and formed a false joint, but the indications on the bones 

 are that a fracture had occurred sulisequent to the development of the 

 sidebone, and not that the ossification had commenced high up in the 

 cartilage and extended downwards with failure to unite with the basilar 

 process of the wing of the os pedis. 



It, doubtless, is the case that many draught horses when worked in 

 pairs or in teams abreast are trodden on at the seat of the sidebone and 

 that some of such horses may subsecjuently develop sidebones. Many so 

 trodden on, however, dO' not develo]> sidebones and the logical inference 

 is that when sidebones de^•elop after actual or supposed injury, they 

 develop despite the injury and not because of it. In such cases, sidebones 

 would doubtless have formed whether injury had occurred or not ; but 

 where injury has occurred and sidebones have been noticed afterwards, 

 the injury is credited with iTcing the cause although the sidebone mav 

 have been present but unnoticed at the time the injur\ was sustained. 



Since the attention of horse-owners has been so pointedly called to 

 the subject of sidebones by the results of the Government examination of 

 stallions, manv of them have given me instances within their own experiences 

 on their own farms which corroborate the conclusions above set out — cases 

 in which certain horses on the farm related to one another have all 

 developed sidebones, but the remaining horses on the farm, worked and 

 treated in exactly similar fashion but unrelated to the sideboned horses, 



have remained sound. Mr. K C , of Y-— , has five 



descendants of one mare all bred <>n his farm and all sideboned, while 

 seven other home-bred horses, unrelated to the mare iii questior, but which 

 have been reared and worked under the same conditions as her descendants, 

 have remained sound. 



Work versus Heredity in the Production of Sidebones. 

 The only set of figures bearing on the incidence of sidebone which I have 

 come across in any veterinary text-book are those by Lungwitz, quoted in 

 Mollar and Dollar's Veterinarij Surgery. Lungwitz examined 1,251 horses, 

 and furnished the following table of results : — 



Description. 



Belgian Cart Horse 



Danish Carriage Horse 

 Heavy Riding Horse 



Heavy Riding Horses 

 Light Riding Horse 

 Riding Horses (various- 

 weights) 

 Military Horses 



Officers' Horses (heavy) . . 



Number 

 of Horses 

 Examined. 



98 



120 



388 



132 

 133 

 140 



200 



40 



1,251 



Number 

 affected 



witii 

 Sidebone. 



68 



25 



3(5 



144 



Percent- 

 age. 



Remarks. 



69-5 



31 



Working onlj' on hard 

 pavements 



9 I Working on heavy ground 

 and partly on hard pave- 

 ments ' 

 Working on light sandy soil 

 f) Working on light gronnd 

 Workmg on liglit ground 



0-5 



7-5 



14-4 



Working on medium heavj- 



ground 

 Working on varied surfaces 



