lo May, 1910.] Hereditary Unsoundness hi Horses. 343 



Thirdly, as to relative frequency of near side and ofE side affection — 



Of the above-mentioned 254 horses having sidebone in front — 



197 horses had sidebones both fore = 394 feet affected 



16 „ „ near fore only = 16 „ „ 



41 „ „ off fore only = 41 „ „ 



Total .. 254 Total 451 „ 



Of these 451 affected feet, 213 were near fore and 238 off fore, viz. : — 197 + 16 = 

 213 near fore, and 197 + 41 = 238 off fore. 



Fourthly, as to the relative frequency of sidebone on the inside and out- 

 side of the foot — 



Of the above-mentioned 254 horses having sidebone in front only — 

 147 had 4 sidebones (588 individual sidebones) — 294 inside and 249 outside 

 32 „ 3 „ ( 96 „ „ ) 36 ., „ 60 



46 „ 2 ,. ( 92 „ „ ) 24 „ „ 68 



29 „ 1 „ ( 29 „ „ ) 9 „ „ 20 



254 horses sidebone (805 „ „ 363(45.1%) „ 422 (54.9%) outside 



in front 



(a proportion of 9 inside to 11 outside). 

 Of the 46 horses shown in this Table as having two sidebones in front, 28 were affected 

 on one foot only ; the remaining 18 had one sidebone on each foot, makmg 36 sidebones 

 in all (18 X 8). Of these, 6 were inside and 30 outside. Tlierefore, the number of horses 

 having sidebones on both feet was 197 (18 + 32 + 147). These 197 horses had 720 

 individual sidebones between them (588 + 96 + 36), distributed as follows : — 



7-^0 sidebones i ^^^ °"*'^^^ ^^^ " ^%) 



/.u siaeoones . . | ^^g j^^.^^ (46-7%). 



336 inside (46-7%). 



48 more sidebones on outside than inside — a jiroportion of 

 8 (outside) to 7 (inside). 



The outstanding features of the above figures are — 



(a) The great excess of sidebones in the fore foot as compared with the 



hind — proportion 13 to 1. 



(b) The preponderance of cases in which both fore were affected as 



against one-foot affection — proportion 10 to 3. 



(c) The approximation of the incidence of sidebone in the near and 



off foot — proportion 9 to 10. 



(d) The approximation of the incidence of sidebone on the inside 



and outside of the foot respectively — proportion 9 to 11, in- 

 clusive of single-footed sidebones ; 7 to 8 for pair foot side- 

 bones only. 



Concerning A, it is reasonable to regard the excess of sidebones in 

 front as positive evidence of the part played by concussion and strain of 

 body weight as exciting causes of sidebone. More weight is borne during 

 rest and greater concussion is sustained during movement by the fore limbs 

 and feet than the hind limbs and feet, for two reasons : — 



Firstly, the incidence of body weight on the fore feet is greater 



than on the hind ; 



Secondly, the column of bones of the fore limbs, being practicallv 



perpendicular from the elbow down, is more rigid than that 



of the hind limb, in which the angle formed by the tibio- 



metatarsal bones tends to lessen iar. 



The effect of concussion in the production of Splints might be adduced 



in support of the above conclusion. It is definitely recognised that the 



greatest exciting cause of " splints " in light horses is concussion. Their 



occurrence in the metacarpal region is, as compared with the metatarsal, 



