DISEASES OF HEAKT, BLOOD VESSELS, AND LYMPHATICS. 263 

 CONGESTION OF THE HEART. 



Congestion, or an accumulation of the blood in the cavities of the 

 heart, may occur in consequence of fibrinous deposits interfering 

 with the free movements of the valves, usually the product of endo- 

 carditis or as a result of excessive muscular exertion. 



Symptoms are great difficulty of breathing, paleness of the visible 

 mucous membranes, great anxiety, frequently accompanied by a gen- 

 eral tremor and cold perspiration, followed by death. It usually 

 results in death very qUickly. 



CYANOSIS OF NEWBORN FOALS. 



This is a condition sometimes found in foals immediately after 

 birth, and is due to nonclosure of the foramen ovale, which allows a 

 mixture of the venous with the arterial blood in the left cavities of 

 the heart. It is characterized by a dark purple or bluish color of the 

 visible mucous membranes, shortness of breath, and a general feeble- 

 ness Foals thus affected generally live only a few hours after birth. 



DISEASES OF ARTERIES, OR ARTERITIS AND ENDARTERITIS. 



Inflammation of arteries is rarely observed in the horse as a pri- 

 mary affection. Direct injuries, such as blows, may produce a con- 

 tusion 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 production of 

 a general endarteritis. Septic infection may affect the inner coat 

 and ultimately involve all three, or it may be the result of an inflam- 

 mation in 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. 



Symptoms. — Arteritis is characterized by a painful swelling along 

 the inflamed vessel, throbbing pulse, coldness of the parts supplied by 

 the inflamed vessel, sometimes 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. 



Pathology. — In acute arteritis we find swelling along the vessel, 

 loss of elasticity, friability, and thickening of the walls ; a roughness 

 and loss of gloss of the inner coat, with the formation of coagula or 

 pus in the vessel. Subacute or chronic arteritis may affect only the 

 outer coat (periarteritis), both the outer and middle coat, or the 

 inner coat alone (endarteritis) ; and by weakening the respective 

 coats leads to rupture, aneurism, or to degenerations, such as bony, 

 calcareous, fatty, atheromatous, etc. It may also lead to sclerosis or 



