CAEE AND MANAGEMENT OF ANIMALS 763 



oxygen. This produces exhaustion, while at the same time 

 the effect of carbonic acid on the respiratory centre, and 

 the engorgement of the heart, is to set up increased diffi- 

 culty in breathing. 



We cannot here enter into all the physiological problems 

 concerned in training, we have touched on those of the 

 greatest importance, viz., the conditioning of the heart and 

 bloodvessels, skeletal muscles, and the respiratory problem, 

 all of which are of considerable complexity, and of which 

 we only know the beginning and the end. 



It is quite impossible to exaggerate the influence of con- 

 dition, no horse intended for work can be safely worked in 

 its absence, it is unfair to the animal, and a species of 

 cruelty such as the ordinary lay mind fails to recognise until 

 pointed out. 



What man that has been living a life of idleness can 

 suddenly be put to hard work? Common-sense dictates 

 that work must be light in the first instance, and gradually 

 increased as the muscular and circulatory systems improve 

 in tone. Exactly the same thing applies to horses, only to 

 a more marked degree ; for example, if a man is in training 

 for a race he only has to carry the weight of his own body, 

 but a horse has to carry not only the weight of its own body 

 but that of its rider. In all cases of the conditioning of 

 horses this must not be lost sight of, as a matter of fact it 

 is never remembered, the only weight to which we pay 

 attention is that which is placed on the animal's back or 

 behind it; it is completely forgotten that there is the 

 horse's own body-weight to consider, which he must first 

 get fit to carry before any work can be expected from 

 him. 



Any calculation of the effort exerted to carry the body is 

 a complex problem, and for the horse, has never, so far as 

 we know, been determined by mathematicians ; but it has 

 been shown in the case of man that one twentieth part of 

 the body-weight is expended in propelling it at three miles 

 an hour on a level surface. This number is called the 



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