98 A MANUAL OF VETERINARY PHYSIOLOGY 



muscular cramps occur, and finally temporary paralysis follows. 

 These symptoms completely pass away with rest and return with work. 



Parasitic trouble of the vessels is very common, the main seat being 

 the anterior mesenteric artery, which is rendered rigid and aneur- 

 ismal, and has its lumen obliterated by Strongylus armatus. It is 

 remarkable how very little interference with the intestinal circulation 

 occurs in consequence of this parasitic invasion, and it is equally 

 astonishing how few horses are free from this infection. It is 

 probably the most widely spread equine parasite. 



Pulse. — The older physicians studied the pulse with care ; at the 

 present day it does not receive the same amount of attention. It is 

 not sufficient to know the number of pulsations ; the important point 

 is the character of the wave. 



A pulse may be quick or slow. Either of these may be strong, 

 weak, hard, or soft. Strong and weak refer to the force of the 

 ventricular contraction ; hard and soft refer to the tension as judged 

 by the finger — viz., the amount of pressure required to obliterate the 

 pulsations. A further division of pulses is into large and small ; 

 this group refers to the volume of the artery. There is no pulse 

 specially indicative of any given affection, but the character of the 

 pulse in the prognosis of disease is of the utmost clinical value. 



