DISEASES OF THE FOOT 163 



have side-bones seldom show lameness. This is because they 

 are worked on soft ground and not on a hard street or road. 

 Driving' and drny horses may step short with the front feet, or 

 show a stilty action. This may disappear with exercise. The 

 lameness is sometimes marked. The local diseased changes are 

 the greatest help in the recognition of side-bones. Horses should 

 not be passed as sound without making a careful examination of 

 the lateral cartilages. This examination is made by pressure 

 over the region of the cartilage with the thumb or fingers. This 

 is for the purpose of testing its elasticity. If it feels rigid 

 and rough, the cartilaginous tissue has been replaced by bony 

 tissue, and the animal should be classed as unsound. 



The treatment is largely preventive. Horses with side-bones 

 should not be bred. It is not advisable to use horses with side- 

 bones on the road or city streets. Shoeing with riibber pads may 

 help in overcoming the concussion and relieve the lameness. 

 Sectioning the sensory nerves going to this portion of the foot is 

 advisable in driving horses. Rest and counterirritation relieve 

 the lameness for a short time. 



Navicular Disease. — In navicular disease the bursa, flexor 

 tendon, and navicular bone may become chronically inflamed. 

 Because of the seat of the lameness, it is commonly known as 

 " coflin-joint " lameness. This disease affects standard and 

 thoroughbred horses more often than it does the coarser breeds. 

 One or both front feet may be affected (Fig. 39). 



Hereditary causes are largely responsible for navicular dis- 

 ease. The tendency toward this disease probably depends on 

 such peculiarities of conformation as narrow, weak, high heels, 

 long pasterns and too long a toe. The character of the work is 

 an important factor. Hurried, rapid movements throw consider- 

 able strain on the navicular region, increasing the danger from 

 injury. This is, no doubt, one reason for " coffin-joint " lame- 

 ness being more common in driving and speed horses than in 

 slow-going work animals. Rheumatic inflammation, bad shoeing 



