78 THE SURGICAL ANATOMY OF THE HORSE 



mations of soft and elastic tissue into bone, may be regarded as Nature's 

 means of fortification against more serious failures." 



A reference to our chapter on joints will make clear the fact that the 

 small bones concerned in this disease are intimately connected with one 

 another by short, strong interosseous ligaments, and it will be evident 

 that the greater the gliding movement produced by the bones the greater 

 the danger of these ligaments being sprained and becoming inflamed. 

 Hence sickle or cow hocks are cited amongst those predisposed to the 

 disease, since greater movement is produced between the bones by the 

 action of the flexor metatarsi and gastrocnemius. 



Somewhat similarly may be regarded the action of violent exercise, 

 particularly in young and immature animals. The bones are injured at 

 the attachments of the ligaments, and ostitis results. The jar on the 

 articular surfaces resulting from concussion is stated to be the most 

 important local or exciting cause. Macqueen holds this view. Hence 

 we find spavin frequently developed in young animals with good hind 

 action, but which, through lack of elasticity in their movements, put 

 their feet down with a considerable amount of force, particularly when 

 such animals are worked regularly on hard roads or pavement. 



Peters, quoted by Moller, " thinks soft, moist ground and rough 

 pavements particularly injurious, because the unavoidable rotary movement 

 of the hoof on the ground is interfered with, and consequently takes place, 

 not at the extremity of the limb, but in the joints, especially in the hock 

 joint." From what we have said regarding the eff^ect of undue tension 

 on the ligaments, this view of Peters appears to be very logical. 



External injuries, such as blows, kicks, &c., may be almost entirely 

 disregarded, since the usual situation of spavin is such that the seat is 

 particularly favourable to its protection. 



The disease runs an insidious course. At first in many cases lameness 

 is not very apparent, and what is noticed is that the hock is not flexed with 

 the former freedom. Later there is marked stifiriess in the joint, and still 

 later there is pronounced lameness, particularly when the animal is first 



