DISEASES OF HORSES 373 



DISEASES OF ARTERIES, OR ARTERITIS AND ENDARTERITIS. 



Inflammation of arteries is rarely observed in the horse as a 

 primary affection. Direct injuries, such as blows, may produce a 

 contusion and subsequent inflammation of the wall of an artery; 

 severe muscular strain may involve an arterial trunk; hypertrophy 

 of the heart, by increasing arterial tension, may result in the pro- 

 duction of a general endarteritis. Septic infection may affect the 

 inner coat and ultimately involve all three, or it may be the result 

 of an inflammation of the vicinity of the vessels, etc. Inflammation 

 of arteries, whatever the cause may be, often leads to very serious 

 results in the development of secondary changes in their walls. 

 Arteritis may be acute, subacute, or chronic; when the inner coat 

 alone is affected it is known as endarteritis. Arteritis is character- 

 ized by a painful swelling along the inflamed vessel, throbbing 

 pulse, coldness of the parts supplied by the inflamed vessel, some- 

 times the formation of gangrenous sloughs, suppuration, abscess, 

 etc. In an inflammation of the iliac arteries we find coldness 

 and excessive lameness or paralysis of one or both hind limbs. The 

 treatment is carbonate of potassa in 1-dram doses, to be given in 

 4 ounces of liquor acetate of ammonia every six hours ; scalded bran 

 sufficient to produce loosening of the bowels, and complete rest; 

 externally, applications of hot water or hot hop infusion. 



ATHEROMA. 



Atheroma is a direct result of an existing chronic endarteritis, 

 the lining membrane of the vessels being invariably involved to a 

 greater or less degree. It is most frequently found in the arteries, 

 although the veins may develop an atheromatous condition when ex- 

 posed to any source of prolonged irritation. Atheroma may affect 

 arteries in any part of the body; in some instances almost every 

 vessel is diseased, in others only a few, or even parts of one vessel. 

 It is a very common result of endocarditis extending into the 

 aorta, which we find perhaps the most frequent seat of atheroma. 

 As a result of this condition the affected vessel becomes impaired 

 in its contractile power, loses its natural strength, and, in conse- 

 quence of its inability to sustain its accustomed internal pressure, 

 undergoes in many cases dilatation at the seat of disease, constitut- 

 ing aneurism. In an atheromatous vessel, calcareous deposits soon 

 occur, which render it rigid, brittle, and subject to ulceration or 

 rupture. In such vessels the contractility is destroyed, the middle 

 coat atrophied and beyond repair. Atheroma in the vessels of the 

 brain is a frequent cause of cerebral apoplexy. No symptoms are 

 manifested by which we can recognize this condition during life. 



CONSTRICTION OF AN ARTERY. 



This is usually the result of arteritis, and may partly or wholly 

 be impervious to the flow of blood. When this occurs in a large 

 vessel it may be followed by gangrene of the parts; usually, however, 

 collateral circulation will be established to nourish the parts pre- 

 viously supplied by the obliterated vessel. In a few instances con- 

 striction of the aorta has produced death. 



