130 THE SURGICAL ANATOMY OF THE HORSE 



Occasionally the chronic enlargement remains on one side of the tendon 

 only. At other times the thickened portion is very short — only about 

 an inch in length. 



In all cases the swelling in the early stage is due to inflammatory 

 exudate or hasmorrhagic extravasation, or both, but the chronic swelling 

 is the result of a new growth of fibrous tissue. 



As regards causation, the tendons may be sprained by slipping, or 

 landing on loose ground when jumping, or by the taking of a false step. 

 In heavy horses the tendons are frequently sprained through sudden 

 tension being thrown upon them when starting a big load, or in holding 

 back the load when descending a hill. Young animals frequently sprain 

 their tendons through slipping when galloping in wet weather. 



The symptoms presented vary according to the tendon sprained. 

 When the perforans is affected lameness invariably occurs, the degree of 

 which is in proportion to the severity of the sprain. When resting, the 

 animal either advances the foot three or four inches in front of the 

 opposite foot, or holds it opposite the other foot with the fetlock 

 knuckled (this relieves the tension on the affected tendon). There is 

 swelling at the seat of the sprain, which is very painful to the touch. 



There are several affections which may be mistaken for a sprain of 

 the tendon in the early stages. It may be symptomatic of pricked foot, 

 crushed heel, a tread, corn, or a sand crack, any of which may give rise 

 to a swelling over the tendons. It is thus necessary to examine the 

 whole limb most carefully after the manner indicated in our superficial 

 examination, and to have the shoe removed before giving a definite 

 opinion. 



After the lapse of twenty-four hours the condition is much more 

 easily diagnosed, and the sprained part is then very sensitive to the 

 touch. 



Sprain of the perforatus tendon is very different. It may exist 

 without much lameness, and the animal may even trot fairly well. In 

 this case we usually get what is commonly known as " bowed sinew." 



