THE VEINS. 247 



Symptomatic fever is increased arterial action, proceeding from some local 

 cause. No organ of consequence can be much disordered or inflamed without 

 the neighbouring parts being disturbed, and the whole system gradually parti- 

 cipating in the disturbance. Inflammation of the feet or of the lungs never 

 existed long or to any material extent, without being accompanied by some 

 degree of fever. 



The treatment of symptomatic fever should resemble that of simple fever, 

 except that particular attention must be paid to the state of the part originally 

 diseased. If the inflammation which existed there can be subdued, the general 

 disturbance will usually cease. 



The arteries terminate occasionally in openings on different surfaces of the 

 body. On the skin they pour out the perspiration, and on the diiferent cavities 

 of the frame they yield the moisture which prevents friction. In other parts 

 they terminate in glands, in which a fluid essentially different from the blood is 

 secreted or separated : such are the parotid and salivary glands, the kidneys 

 the spleen, and the various organs or laboratories which provide so many and 

 such different secretions, for the multifarious purposes of life ; but the usual 

 termination of arteries is in veins. 



THE VEINS. 



These vessels carry back to the heart the blood which had been conveyed to the 

 different parts by the arteries. They have two coats, a muscular and a mem- 

 branous one. Both of them are thin and comparatively weak. They are more 

 numerous and much larger than the arteries, and consequently the blood, less- 

 ened in quantity by the various secretions separated from it, flows more slowly 

 through them. It is forced on partly by the first impulse communicated to it 

 by the heart ; also, in the extremities and external portions of the frame, by 

 the pressure of the muscles ; and in the cavity of the chest, its motion is assisted 

 or principally caused by the sudden expansion of the ventricles of the heart, 

 after they have closed upon and driven out their contents, and thereby causing 

 a vacuum which the blood rushes on to fill. There are curious valves in various 

 parts of the veins which prevent the blood from flowing backward to its source. 



BOG AND BLOOD SPAVIN. 



The veins of the horse, although their coats are thin compared with those of 

 the arteries, are not subject to the enlargements (varicose veins) which are so 

 frequent, and often so painful, in the legs of the human being. The legs of the 

 horse may exhibit many of the injurious consequences of hard work, but the 

 veins will, with one exception, be unaltered in structure. Attached to the 

 extremities of most of the tendons, and between the tendons and other parts, are 

 little bags containing a mucous substance to enable the tendons to slide over 

 each other without friction, and to move easily on the neighbouring parts. 

 From violent exercise these vessels are liable to enlarge. Windgalls and thorough- 

 pins are instances of this. There is one of them on the inside of the hock at its 

 bending. This sometimes becomes considerably increased in size, and the 

 enlargement is called a bog-spavin. A vein passes over this bag, which is 

 pressed between the enlargement and the skin, and the passage of the blood 

 through it is impeded ; the vein is consequently distended by the accumulated 

 blood, and the distension reaches from this bag as low down as the next valve. 

 This is called a blood-spavin. Blood-spavin then is tire consequence of bog- 

 spavin. It very rarely occurs, and is, in the majority of instances, confounded 

 with bog-spavin. 



Blood-spavin does not always cause lameness, except the horse is very hard- 

 worked, and then it is doubtful whether the lameness should not be attributed 



