198 THE HORSE IN HEALTH AND DISEASE 



NAVICULAR DISEASE 



Navicular disease is a chronic inflammation of one or more of 

 the following structures: the navicular bone, the navicular joint, 

 the navicular bursa, the perforans tendon. When the pathologic 

 changes first start they are usually confined to the bone itself. 

 There is a progressive rarefying ostitis that finally undermines the 

 articular cartilage and results in erosion to its smooth surface. At 

 this stage pain is pronounced with each and every movement of the 

 joint. Many observations show that navicular disease occurs al- 

 most exclusively in harness horses. The exact cause is often im- 

 possible to locate. There seems to be a particular tendency for it 

 to appear in animals subject to the so-called spavin group of lame- 

 nesses. Whether or not this is an inherited tendency remains to 

 be definitely proved. 



The symptoms are at first hardly noticeable. Quite without 

 warning the horse may limp, but after a few steps recovers. When 

 resting the foot is advanced or "pointed" and the toe is placed on 

 the ground. The fetlock is flexed to take pressure off the navicular 

 apparatus. Later intermittent lameness occurs. In more ad- 

 vanced cases of the disease the patient becomes severely lame for 

 a week or more. This may continue or disappear, only to recur 

 after weeks or even months. Finally, lameness is constantly 

 present and is aggravated with use. The heels contract, the feet 

 dry out, the frog atrophies, the toe of the shoe wears away more 

 rapidly than normally as it strikes the ground first, the horse 

 stumbles, particularly when going up hill, and the gait is stiff. 

 One writer summarizes the symptoms as follows: "Unless the case 

 is bad the horse 'points,' raises his heel, and rounds his fetlock joint 

 when standing. He walks sound, but when trotted goes 'short,' 

 'daisy cuts,' and 'digs his toes into the ground.' " 



From what has been said about the pathology of navicular dis- 

 ease it is clear that few cases recover. Mechanical means to relieve 

 the animal and render him serviceable are the most sensible forms 

 of treatment. A plane shoe, without a bar or toe-calk, is best. 

 If lameness persists, neurotomy may be performed to destroy sen- 

 sation in the foot. 



SHOEING 



Before perusing this section, the one on the structure and func- 

 tions of the foot should be carefully reviewed, as the information 



