U)22 DISEASES OP THE HOCK. 



in spite of work ; sometimes it disappears for a time, but generally 

 returns with rest : often it is only noticeable when the animal is 

 turned in small circles or moved from side to side. 



The immediate cause of this interference with movement has been sought 

 [or in different organs, but up to the present has not been identified. 

 Abildgaard considered the condition to be an "affection" of the muscles 

 and nerves of the hind Limb. Villate thought it was caused by abnormal 

 development of the spine of the tibia. Sevvell and Spooner, when making 

 the post-mortem of a horse affected with stringhalt, found that the point 

 of origin of the great sciatic nerve in the spinal cord was infiltrated with 



hi 1. and regarded this as the cause of the disease. Falke identified the 



condition with sciatica in man. Renner took it to be due to chronic inrlam- 

 niation of the great sciatic nerve, whilst Hochstetter attributed it to 

 straightness of the hocks ; Boccar sought the cause in contraction of the 

 peroneus, after discovering that the condition disappeared on section of 

 its tendon. Foelen and many others agreed with him, and reported favour- 

 able results from dividing the tendon. Goubaux, on the other hand, 

 directed attention to the joints, especially to the hip-joint, which in his 

 view became chronically inflamed in stringhalt. K. and F. Giinther divided 

 it into the following varieties : — 



(1) Spavin-stringhalt, i.e. stringhalt caused by spavin. (2) False string- 

 halt, produced by pain in any region of the limb ; and (3) True or involuntary 

 stringhalt, due to irregularities in the functions of the antagonistic nerves 

 of the lumbar and pelvic plexuses. 



The Giinthers state having frequently seen hyperemia of the great 

 sciatic nerve without stringhalt, but add that stringhalt is sometimes 

 accompanied by relaxation in the semi-tendinosus muscle. The}^ first 

 drew attention to the connection between stringhalt and certain surgical 

 diseases — as, for instance, those of the foot. 



Dieckerhoff divided the disease into — (1) True idiopathic stringhalt, 

 which he considered due to contraction in the fascia of the thigh. (2) Com- 

 plicated stringhalt, accompanying spavin, curb, ring-bone, and other 

 diseases. (3) Symptomatic stringhalt, consequent on inflammation in 

 the pedal or other regions of the limb. 



Bassi recognised two forms : — (1) True stringhalt, caused by interference 

 with the movement of the patella ; and (2) false stringhalt, caused by a 

 number of other diseases, such as spavin, horn tumour, &c, but principally 

 by contraction of the tensor vaginae femoris, and extensor pedis tendon. 

 Other forms in horses he considers due to brain disease, resulting from 

 asymmetry of the skull, and in dogs to changes in the spinal cord following 

 distemper. 



Mciller divides stringhalt into idiopathic and symptomatic forms, 

 and includes in the first those cases due to no visible cause ; and, 

 in the second, those where a cause can be detected. 



Whatever be the cause, it is quite certain that the movement is 

 involuntary. It must, therefore, be dependent on some mechanical 

 action, e.g., contraction of the fascia, of the tendons, or of the liga- 

 ments, or on reflex action, originating either directly in the spinal 

 cord, or through interference with innervation. Probably both 



