UNSOUNDNESS IN HORSES.

Dominion, Volume 3, Issue 829, 30 May 1910, Page 10

UNSOUNDNESS IN HORSES.

SIDEBONE AND HEREDITY

Tho most common form of unsoundness met with, in horses is. sidebone. Many breeders hold that this defect is - caused by .external injury or the. unequal incidence of concussion brought about by. tlfe use of calkin shoes. Considerable doubt has been entertained as io .whether sidebone is hereditary. Valuable light-is thrown on this important question by the records which havo been'compiled by Mr. S. S. Cameron, M.K.C.V.S., D.V.Sc., of Victoria, ' aud which are published in the current .number of the "Victorian Journal or • Agriculture." Mr. Cameron has noted the occurrence or otherwise of sidebone in. the progeny or sideboned or sound parents throughout a series of generations in different families of horses. ■ ; • ■ ' •'•. . Of the 2636 horses examined m Victoria in "the three years sincp'.the ex- ' amination' of stallions has been in force, 20.17 .per cent, of the draughts, 0.51 per cent, of the light horses, and none of the ponies were registered for sidebone. This form of unsoundness is, therefore, practically confined to draughts, and Mr. Cameron, in his summing-up, says it 'is the most common of. all forms of hereditary unsoundness in draught horses. Only - four light horses out. of 779 were affected with sidebone, and two of these were found 1 to-■ have draught blood in them! This is of. great significance,, as tliest horses by their work and pace are subject in a much greater degree than draughts/ to one of tho alleged principal causes of-the complaint, viz., concussion. As soon as the _ first hundred draughts were -examined, Mr. Cameron saw that information of great ' value as to the inheritance of sidebone could be 'collected,-and caused records to be kept of the pedigrees' and relationships of tho different horses examined. As only stallions were dealt with -the influence of the sire alone could be : traced. As the dam is probably equally as potent in transmitting sidebone the tables are not as exact as could .be desired. ' There is one family, however, in which it appeared • that when the horse was mated with mares belonging to a sidebone sire ' family'tho offspring developed sidebones, but when mated with outside mares the offspring remained sound; •The following tablo gives particulars of the records of the families (horses the progenj., o£,one_sire) examined: — .-. Sons,. Grandson's. Side- ■ SideFamily. boned. Sound, boned. Sound. Unsound families — • . A ......... 9 2. 15- .13 : ' B 8 4 7 6 C ' .4 0 1 . 1 D3O 1 0 . ■ -E- " ...: '4 o - 1- . 0 .. ■F. 30 ■: 0 0 . Sound families— ' - A- ......... L 19 7 15 ' v B» 0 2 1 13 C ......... 1 19 — • - D 0 12 — — : E 0 8 13' F ■ — ' — 0 10 G 2 10 — —, . H ......... 0 8 0 1' - I 0' 6 0 1 J 0.4 — — '

, *In this family 15 great-grandsons ; were also sound, and none sideboned. " As to the location of sidebone, Mr. Cameron found that of 275 sideboned i. horses, 40 had sidebone on one foot 1 : . 'only, 214 on two feet, Bon three feet, ' .and 13 on four-feet. Then 254 of the horses had sidebone in front only, two ! ' behind,'and 19 both in front and ber hind. Mr,' .Cameron states that he' " found very-little evidence in favour of the theory of injury as a cause of sidebone.: ' -. Particttlars ■ are . also given of ..horses / rejeictcd on other grounds.- Of 40 horses passed out for ringbone, five bc- ;. longed to one family/and four to.an-; -!. i. other. Seven families ' were . found in* ?V, which near.relatives were affec.ted with • curb. . The . evidence of . heredity in bog-spavin (including thorough-pin) was _ more :pronounced than in resect to there being no fewer than nine families in which a varying number of descendants were affected. * Suf- > , ficient evidence was not available to say , whether bone spavin'was hereditary.