i8o 



Common Diseases of the Horse 



the pastern bone, is the coronet bone. Other important structures 

 which the hoof contains are the bloodvessels, nerves, tendons, some 

 of the membranes which secrete the horn, and the elastic structures, 

 in which are included the lateral cartilages. 



The back and lower part of the foot is made up of the horny 

 frog. Above it is the sensitive frog, and above this again more elastic 

 tissue, i.e. the plantar cushion. The sides of the foot are continued 

 backward to the heel, from what is called the wing of the coffin 

 bone, by two irregular elastic plates, known as the lateral cartilages, 

 contained partly within the horn, their upper borders being entirely 

 free. To the touch, they should be resilient or elastic as though 



composed of india- 

 rubber. The function 

 of the whole of the 

 elastic structures is 

 to prevent concussion, 

 and thus protect the 

 delicate tissues of the 

 foot from the effects 

 of concussion, and 

 also, by expanding 

 and contracting as 

 the weight is on the 

 foot or otherwise, to 

 maintain its shape. 



Sidebone occurs 

 when the elastic lat- 

 eral cartilages become 

 hardened and converted into bone. The causes of the disease are 

 no doubt hereditary. In addition, the method of shoeing plays 

 a most important part, and in some cases injury to the cartilage, 

 such as by a tramp or a tread, or some mechanical object may be 

 responsible. Under natural conditions, or when the horse is shod 

 with flat shoes, the frog should assist in bearing its due proportion 

 of the body weight. When unnatural conditions have to be adopted 

 to enable the horse to perform his work, and calkins or high 

 upright heels are put upon the shoes, as they have to be in towns, 

 then the frog is out of use, and undue weight is thrown upon the 

 heels. 



In a great measure this will account for the much larger per- 

 centage of sidebone occurring in town horses compared with those 

 in the country, where flat shoes are generally used. 



The disease is found most commonly in the heavy draught 



Pedal Bones, showing ossification ol lateral cartilages, 

 constituting "sidebones". 



