358 



HEALTH AND DISEASE 



has known it to appear in every animal bred by certain mares, and in many 

 of the produce of certain affected sires. Horses with straight, weak hocks, 

 short at the point, are its most common victims. 



The inducing causes are excessive feeding, and the too early and severe 

 working of ill-conditioned colts. It is often contracted by yearlings at 

 play, and by older animals from severe sprains otherwise induced. Hard 

 work on slippery ground is a common cause of thoroughpin in its more 

 chronic and progressive form. It is frequently associated with bog-sj)avin, 

 of the nature of which it very much partakes. 



Symptoms. — The enlargement which constitutes the special feature of 

 thoroughpin may develop in a few hours to a considerable size. This is 



especially the case in young 

 animals, and in older ones also 

 where it arises out of severe 

 sprain. Other cases are less 

 sudden in their appearance, and 

 gradually increase in size through 

 a long period of time. In the 

 former case pain and lameness 

 is usually sudden and severe, 

 the swelling hot and tense, like 

 a forcibly distended bladder, and 

 there may be more or less general 

 filling of the joint. The enlarge- 

 ment is sometimes much more 

 considerable on one side than 

 the other, at others it is uniform on the two aspects. In action the 

 limb is moved stiffly with an inclination outward. At rest it is main- 

 tained in a flexed condition, the weight being impo.sed on the sound 

 leg. Where the disease comes on gradually lameness may for a time 

 be altogether absent, owing to the accommodation which by growth and 

 expansion the tendon -.sheath is enabled to afl'ord the slowly -increasing 

 fluid. The time, however, comes sooner or later when the sheath is unduly 

 and suddenly sti'Ctched, and pain and lameness result in consequence. In 

 old chronic cases of this kind the tendon-sheath becomes very much 

 thickened, and sometimes by undergoing calcareous degeneration is con- 

 verted into a hard bone-like substance. It sometimes occurs that an 

 enlargement similar to the one described presents itself on both sides 

 of the hock as a result of bog-spavin. AVhere this is the case a similar 

 fullness will mostly be observed in front over the seat of the last-named 

 disease. 



Fig. 383. — Compresses for Thoroughpin 



