CAUSES OF LAMENESS. 241 



ing, "treads," wounds, ulcers, rheumatism, and reflex nervous 

 action, as in diseased liver. 



A SPRAIN, OR STRAIN, 



Is violence inflicted upon any soft structure, with extension, and 

 often rupture of its fibres. Professor Dick was of opinion that 

 there was always rupture of the fibres in a sprained tendon or 

 ligament. But I think that the condition which we term strain 

 may arise from repeated extension or slight stretching, without 

 the fibres being at first ruptured at all; and that an altered 

 nutrition is so produced, which leads on to inflammation of the 

 part, with interfibrillar exudation, and finally to the softening of 

 some portion of the fibres, by which they lose their toughness, 

 and become broken across. A very slight strain may be a mere 

 bruise, with ecchymosis ; whereas violent and great extension 

 may rupture the whole structure of a part. 



Extension is not always the cause of a strain, as a muscle may 

 be injured by the opposite condition, namely, violent contrac- 

 tions ; its fibres and their thecae broken across their long axes ; or 

 its tendinous fibres torn from their attachments at either or both 

 of its extremities. 



Strains may be confined to the thecce or sheaths only, but 

 these are of but little importance compared with injury to the 

 ligaments or tendons themselves. It has been already stated 

 that synovitis may arise from strain of a ligament, by the inflam- 

 mation extending to the small synovial surface which is found 

 on most " binding ligaments." 



Muscular strains are found in various parts of the trunk and 

 limbs. Thus, a horse may be strained in the neck, as a result 

 of a fall upon the head. If the fall be very severe, the strain 

 may be complicated with severe injury to the spinal cord, or 

 with fracture of the vertebrse, causing perhaps the sudden death 

 of the animal. 



The muscles of the dorsal region may be sprained by the hind 

 feet slipping backwards. Wlien a muscle is strained the injury is 

 succeeded by pain, swelling, heat, and loss of function. An in- 

 flamed muscle can no longer contract ; hence, in some strains, 

 the symptoms resemble those of paralysis. 



This swelling of an inflamed muscle is very often succeeded 

 R 



