OF VETERINARY MEDICINE. 



19 



4. Hard and sof t — this characteristic 

 measures the compressibiHty of the 

 artery. 

 When the pulse gets very small and hard, it is said to be 

 ^viry— the artery feels like a wire— or thready, as it is some- 

 times called. In inflammatory diseases of mucous membranes 

 the pulse is not as wiry as in the inflammation of serous mem- 

 branes. A pulse is soft because it is more compressible than 

 normal. This is due to prostration of the nervous system. The 

 softest pulse we ever meet with is that of acute bronchitis— a 

 very light pressure will cut it off entirely. 



The dicrotic pulse is one composed of two beats, both 

 of which correspond to one beat of the heart. The two beats 

 are quite distinguishable to the touch. The phenomenon is only 

 an exaggeration of what occurs in the normal pulse. After each 

 systole the volume of blood in the aorta recoils, thus developing 

 a new positive wave, the dicrotic wave or recoil wave. In certain 

 fevers, when the pulse is soft, this secondary wave can be felt. 

 The best illustration of a dicrotic pulse can be found in a case of 

 azoturia three days old. In this condition there is not force 

 enough in the left ventricle to empty itself and the systolic action 

 is wavering. The natural effect of this is to produce passive 

 congestion in the capillaries. 



An irregular pulse is non-rhythmic in its action ; it may 

 be irregular in frequency, i. e., it may beat at 60 and then jump 

 up to 80 or 90, then drop back again. Or the pulse may be 

 irregular in character; this is apt to occur when the force of 

 the heart muscle is not equal to the work it has to do. 



An intermittent pulse drops one or more beats or 

 even part of a beat at intervals. The intermittency may be reg- 

 ular or irregular. Convalescent cases of pneumonia are apt to 

 develop an intermittent pulse. The most common form is a 

 drop of every fifth beat; an irregular intermittency may occur 

 as a drop of every fifth, seventh and seventeenth beat, etc. 



Venous Pulsed— This is seen in the jugular vein, due to 

 weak cardiac action. It is produced by the blood flowing back 

 into the jugular during the systolic action of the right side of 

 the heart. In horses the jugular pulse always indicates a weak 



