NAVICULAR DISEASE. 911 



The lameness may disappear with long rest, but always returns 

 after hard work. Weeks and months pass, until at last it becomes 

 necessary either to get rid of the animal or to perform neurectomy. 

 Recovery is rare, and supposed cures mostly result from faulty 

 diagnosis or from mistaking remission for recovery, as shown by 

 the opinions of the older English authors, who put the average of 

 recoveries at 90 per cent. Bracy Clark, an able observer, assesses 

 them, on the other hand, at 1 in 16. From the nature of the disease, 

 recovery must be rare, and can only occur during the first stages, 

 i.e., while the disease is confined to the bursa of the flexor tendon. 

 Prognosis is most favourable when, on account of the sudden onset of 

 lameness, there is a probability that inflammation is confined to the 

 tendon and bursa, and that the tendinous surface of the navicular 

 bone is still intact. But when atrophy of muscle or hoof has set in, 

 improvement is not to be expected. Exceptional cases are seen, 

 however, where recovery, or at least cessation of lameness, is produced 

 by adhesion of the perforans tendon to the navicular bone. Gerke 

 confirmed this by a post-mortem two years after the disappearance 

 of lameness. Peters had a similar case, but such a termination is 

 very exceptional. 



Neurectomy, often resorted to to remove sensation, is apt to be 

 followed by rupture of the perforans tendon. The tendon becomes 

 more and more abraded by the rough surface of the navicular bone, 

 until at last, at a moment of excessive strain, it suddenly tears 

 through, leaving the horse completely useless. Temporary improve- 

 ment following long rest must not be mistaken for cure. 



The disease is very common, and is often confused with diseases 

 of the hoof and other lamenesses. Errors are easy, unless plenty 

 of time is given to the examination, and diagnosis sometimes proves 

 difficult, even to the most practised. 



Navicular disease may be mistaken for sprain or wrenching of 

 the ligaments of the coronet-joint. This lameness is usually more 

 severe. The posterior surface of the coronet-joint is then the seat of 

 pain, whilst pressure on the sole causes no flinching. The symptoms 

 of sesamoid lameness present a certain similarity to those of navicular 

 disease (see " Sesamoid Lameness ") ; a careful local examination 

 is therefore necessary. 



Treatment. As above stated, recovery is only possible when the 

 local changes are capable of repair. Disease which starts as an acute 

 bursitis or tenositis offers some chance of cure, though inflammation 

 soon extends to the fibro -cartilage of the navicular bone, and the 

 condition becomes as intractable as if it started at this point. In 



