DISEASES OF THE METATARSUS. 1029 



E. DISEASES OF THE METATARSUS. 



I.— DISEASES OF THE TENDONS AND TENDON SHEATHS IN THE 

 TARSAL AND METATARSAL REGIONS. 



In the horse, the tendon sheaths, both in the hock and metatarsal 

 regions, sometimes become distended, producing conditions of great 

 practical importance. Amongst the most important are — 



(a) Distension of the synovial sheath, which lines the tarsal arch 

 and covers the flexor pedis perforans, producing two unequal dila- 

 tations (tendinous thoroughpin) one on each side in front of the 

 tendo A chillis. Usually the inner swelling is the larger. In some 

 hocks, particularly curbiform and cow-hocks, the same sheath produces 

 interiorly another dilatation, which follows the course of the flexor 

 tendon to the upper third of the shank. 



Disease of this sheath is rather frequent in the horse and 

 occasionally produces a hemispherical swelling as large as a child's 

 head. Sometimes it attacks both legs simultaneously, without 

 causing much lameness (Fig. 551). It may in time decrease and 

 even entirely disappear, especially under proper treatment. In 

 other cases, the inferior portion of the sheath lying towards the back 

 of the hock becomes distended, and may be mistaken for curb, for 

 which reason it has been called curb-gall, or soft curb. 



In other cases acute inflammation sets in. Bruises and injuries 

 may cause septic tendo -vaginitis, accompanied by severe lameness 

 and high fever, which sometimes prove very serious. The condition 

 is even more dangerous if inflammation extend to the joint (see 

 " Wounds, &c, of the Hock -joint "), or produce necrosis of the sheath 

 or flexor tendon, followed by rupture. 



Tendinous thoroughpin occurs in both old and young horses, 

 and usually arises gradually, without causing any inconvenience. 

 In other cases the swelling appears suddenly, accompanied by 

 lameness, and considerable local pain. It is caused by drawing 

 heavy loads, violent efforts, jumping, throwing the horse on his 

 haunches, rearing, &c. Probably there is a predisposition to 

 distension of this sheath in certain horses. 



Prognosis. In many cases the swelling is small and unimportant. 

 It may slowly increase in prominence or it may diminish, especially 

 during winter. Occasionally, owing to injury the local inflammation 

 becomes intense, synovia escapes and the animal, very lame, rests 

 the leg continuously ; but so long as the sheath remains aseptic, 

 recovery should be expected. Pyogenic infection of the tarsal sheath 



