910 NAVICULAR DISEASE. 



recommends exercising the horse after applying a bar-shoe, the bar of 

 whi.h covers the centre of the frog. This increases the lameness 

 in real cases of navicular disease. 



In some cases forcible dorsal flexion gives pain. The foot is lifted 

 as in shoeing, and the toe pressed slowly and powerfully downwards, 

 or the horse is so placed that its toe rests on an elevation, thus 

 causing the heels to be abnormally low when weight is placed on 

 the foot. The same thing often occurs accidentally when the horse 

 is moved on uneven ground, and produces very marked lameness. 



As a rule, there is no great increase in the warmth of the foot, 

 but in advanced cases the foot varies much in temperature. During 

 the further course of the disease the hoof contracts, and the heels 

 become longer and narrower. As the patient no longer places weight 

 on the foot, local nutrition and horn production suffer, and the 

 coronary band appears more prominent, and seems swollen. The 

 uprightness of the pastern causes the hoof to take a more perpendicular 

 position as time goes on. The frog is also relieved of pressure, and 

 this, with defective expansion of the hoof, leads to shrinking of the 

 heels and atrophy of the frog — in short, to contraction of the foot, 

 the sole then appearing abnormally concave. Although contraction 

 of the hoof is important in diagnosis, it should never alone be relied 

 on, because, as Haubner pointed out, the left foot is often smaller 

 than the right. 



The quality of the horn also suffers during the disease. The 

 wall frequently appears uneven, rough, or covered with rings, and 

 its horn brittle. 



In the later stages the muscles of the shoulder become more or 

 less atrophied, depending on the degree of lameness (atrophy of 

 inaction). 



In the diagnosis of navicular disease attention should be directed 

 to the discovery of its typical symptoms : pointing the foot, which 

 may be only advanced a few inches, wearing the toe of the shoe, 

 upright pastern, alteration in the shape of the foot (narrow heels, 

 atrophied frog, increased concavity of the sole), and lameness with 

 short, " pottering " action on the horse first coming out of the stable. 

 or after a short rest, followed by marked improvement of action 

 under exercise. In many cases pointing may be absent or over- 

 looked, and the foot or feet may be normal in shape. By injecting 

 a few minims of a ."> per cent, solution of cocaine over the course of 

 the plantar nerves, temporary anaesthesia of the lower portions of 

 the limb is produced ; disappearance of lameness under these circum- 

 stances suggests that the seat of disease is in the foot. 



