ETIOLOGY AND OCCURRENCE 29 



course and gravity of the affection are directly influenced by the 

 proximity of the injury to lymph plexuses. For instance, in- 

 juries causing an infectious inflammatory involvement of the ad- 

 ductors of the thigh may result in a generalization of the infec- 

 tion by way of the inguinal lymph glands. 



Large open wounds that extend deep into muscles, render 

 inactive such structures, and even where division is not com- 

 plete, the pain occasioned causes the subject to favor the part 

 in every way possible. Contraction of muscular fibers of such 

 parts increases pain and because of this fact groups of muscles 

 are at times disabled because of injury done to one muscle. In- 

 stances of this kind are frequently seen where shoulder injuries, 

 which affect but one muscle, exist; yet because of such injury a 

 marked swinging-leg lameness is present. 



Tendons, because of their inelasticity, are subjected to injuries 

 peculiar to themselves. In addition to being affected as are mus- 

 cles, wounds of many kinds are found to affect tendons — con- 

 tusions, interference wounds, penetrant wounds, incised wounds 

 and lacerations. 



However, the commoner form of injury done tendons, is strain 

 or sprain. Because of the sudden tensile strain brought to bear 

 upon tendons in the shocks of concussion, as well as in propulsion 

 of the body, there frequently occure a rupture of fibers and this 

 we know as sprain. 



Sprains may be considered as fibrillary fractures of soft struc- 

 tures and since this form of injury is sul)surface, and limited to 

 fractional portions of tendons, the inflammation occasioned usu- 

 ally remains an aseptic one. Reaction to this form of injury 

 is characterized by inflammation, the course of which is erratic 

 and variable. In chronic inflammation of tendons, where ani- 

 mals are continued in service, the usual sequel is contraction, or 

 shortening of these structures. 



The degree of contraction as well as its import varies in dif- 

 ferent subjects and in the various tendons which may be affected. 

 Contraction is a slow-going process that is progressive, gradually 

 causing a decrease in the length of the affected structure and 

 eventually rendering the animal useless. 



The practice of applying shoes with extended toe-calks for 



