IXTRIXSIC CAUSES. — EXTRINSIC CAUSES. 2G5 



observer tlie idea of defect in form and muscular tonicity. 

 They seem soft, sluggish, and lacking energy ; their limbs, 

 frequently badly placed in relation to the body, are apparently 

 of extra size, not, however, so much from increase of muscular de- 

 velopment as from abundance of connective-tissue, which in the 

 inferior part of the limb confers upon it a full rounded appearance, 

 and imparts to the hand a sensation of general filling up or 

 padding between bone and ligament, and ligament and tendon, 

 the entire limb taking the character of rotundity and puffiness, 

 not, as in the others, of flatness and firmness of texture ; the 

 hair is generally inclined to be thick and abundant rather 

 than long and silky. It is amongst horses of this latter 

 character, of lymphatic temperament, bulky, badly-formed, 

 sluggish, and having full, rounded legs covered with a profu- 

 sion of coarse, thick-set hair, and showing a great amount of 

 connective-tissue distributed throughout the body, that we find 

 the greatest ^predisposition to Aveed. 



2. Extrinsic Causes.— Oi the factors operating from without 

 in the production of this disturbance of function and subse- 

 quent structural changes, the most potent — in connection with 

 congenital disposition — is probably the importation into the 

 system of nutritive material above the normal demands or 

 wants of the animal, and which may not be utiHzed by con- 

 verting it into a source of reserve. It is perfectly possible, we 

 know, to throw into the animal economy a greater amount of 

 nutritive material than is required to replace the usual waste 

 and to allow for increase of growth, and yet this excess of 

 nutriment to do no positive injury, it being set aside as a 

 source of reserve. Here, however, whether the material pro- 

 vided in excess is too rapidly supplied, or whether it is 

 generally of the variety not most readily converted into fat, 

 the formation of a source of reserve nutrition is less likely 

 to be the result of a rapidly increased supply of nutritive 

 material than the production of a disordered state of assimi- 

 lation. 



The powers of those vessels connected with nutrition, 

 suddenly called upon to bear a great strain, are over-taxed, 

 and gradually or at once they become incapable of exercising 

 their natural functions. Over-taxed and over-loaded, the 

 change from disturbed function to alteration of structure, the 



