274 PARTICULAR LAMENESSES. 



metacarpal and metatarsal bones, and run down the legs, lodged 

 in the fossae upon their posterior aspect, bounded on either side 

 by the small canon bones. They are external and posterior to 

 the suspensory ligament, become attached to the great perforans 

 tendons half way down the leg, and are there placed to prevent 

 over-extension of the tendons. 



Cart-horses are much more liable to this lameness than any 

 other breed, in consequence of the great labour they perform in 

 drawing heavy loads. This can easily be understood by watch- 

 ing a horse start a heavy weight — how he digs his toes into the 

 ground, making his feet fixed points, upon which the muscles, 

 the flexors particularly, are made to act. The muscles acting 

 upon two fixed points, namely, the elbow and foot, render their 

 tendons tense and stretched. Wlien the impetus is given by 

 which the load is started, great strain is thrown upon them and 

 their check ligaments, by which they are extended ; and this 

 extension, acting upon inelastic structures, causes some of the 

 fibres to give way — to become ruptured. Eepeated stretching 

 produces a degenerated condition of the fibres, by which they are 

 rendered easily lacerable. 



I do not hold tliat it is always necessary to have actual 

 rupture of the fibres to constitute a sprain of a tendon or 

 ligament. Inflammation can occur in them, non-vascular as 

 they are, without this lesion ; and extension, although not pro- 

 ducing rupture, is sufficient to produce the inflammatory con- 

 dition, more especially at the points of insertion into the 

 bones. 



An additional cause is found in the kind of shoe that cart- 

 horses wear in some parts of the country, shoes with heavy toe- 

 pieces welded across them. These very materially increase the 

 resistance to the action of the flexors, by adding to the obstacle 

 to be overcome, that obstacle being the foot placed on the 

 ground with the weight of the animal upon it. The foot is ele- 

 vated upwards and backwards, the last part to leave the ground 

 being the toe ; and as it does so it is made to describe the 

 segment of a circle : we tlierefore find that the toe of the shoe 

 is rounded off as it wears. It will easily be understood how 

 any additional resistance to this last act in its elevation becomes 

 a source of disease in the structures which perform it. No one 

 can deny that toe-pieces enable the horse to have a stronger 



