NATURE OF; SPEAIN. 23 



NATURE OF SPEAIN. — Ligameuts, as well as tendoms, may break right 

 across ; or " they may tear, especially small portions of them, here and there, 

 so that the whole thickness is not broken across at any one spot ; but they 

 will not stretch. It is true that under certain conditions they do become 

 elongated, but this only happens when the strain is continuous, and lasts 

 for some considerable time. A slight degree of inflammation sets in then, and 

 under its influence the flbrils soften, until they yield. Sometimes ligaments 

 give way in the middle, but it is more common for them to separate from the 

 bone, or to wrench from it a small thin scale corresponding to their attach- 

 ment. This is due in part to the arrangement of their fibres. In the centre 

 they are woven strongly together, and form a rounded bundle of great 

 strength. At the end they spread out like a fan, so as to secure a wider 

 attachment. A ligament that can resist successfully a straight pull of great 

 violence, yields at once to a twisting force of much less severity ; because this 

 pulls on the fibres unequally, one by one, and tears them from their attach- 

 ment " [Moullin). The fibres of muscles may also become more or less torn 

 from sprain. 



In a sprained tissue, there is not only an inflammatory exudation (p. 14) as 

 a result of the injury ; but there is also, as a rule, extravasated blood, that is, 

 blood which has escaped from vessels that were ruptured at the same time 

 as the broken fibres. In human practice, discoloration of the affected tissues 

 in the case, say, of a badly sprained ankle, often proves the presence in them 

 of extrava-ated blood, which is visible on account of the thinness and trans- 

 lucency of the skin. As a rule, the horse's skin is too thick and too full of 

 pigment to allow of the discoloration in question to be seen through it. 



HOW SPKAINS OCCUR.— In the very common case of lameness 

 due to an acutely swollen fetlock, caused, particularly, by fast 

 work on bard ground, and occurring, usually, to horses with 

 comparatively straight pasterns, we have a good instance of sprain 

 of ligament, brought on by continued and excessive pressure from 

 the i^resence, in the part, of the fluids which give rise to the 

 swelling. Concussion here appears to be the exciting cause. 



In many cases sprains occur only by accident — such as a sudden 

 twist at a moment when the muscles are unable to act quick enough 

 to save the part — or when the muscles have become so fatigued 

 that they are, in this instance also, powerless to preserve its 

 stability. The practical inferences are obvious. 



Experienced horsemen will, I think, agree with me that sprains 

 of the tendons and ligaments of the fore legs — which are the most 

 common accidents to which horses employed in fast work are liable 

 — come on, as a rule, gradually, and as a result of the injm'ed 

 structures having become abnormally weak. The history of the 

 case is usually as follows : — On jDrevious occasions after exercise, 

 heat and tenderness were observed in the part, which symptoms 

 more or less subsided by a short rest having been given, and by 

 the aid of the ordinary remedies, so that the horse was enabled 

 to continue work, off and on, until the day on which the final ac- 

 cident occurred ; or, in other words, until the part, on account of 

 the presence of continued inflammation, or continued tension, be- 

 came too weak to stand the strain of its ordinary work, or of work 

 which would have been well within its poweir had it been in a 



