158 DISEASES OF THE CIRCULATORY APPARATUS 



The normal pulse varies greatly, according to the breed, age, and 

 size of the animal, and is rapidly increased from such causes as phys- 

 ical efforts, fear, fright, pleasure, etc. The general pulse is from 70 to 

 120, in large animals being less and in very small animals having a cor- 

 respondingly freciucnt pulse rate. The rhythm, (cadence) should be reg- 

 ular in a healthy animal, and physical causes make it irregular; but an 

 irregular pulse in perfect health is very common in the dog; in fact, perfect 

 rhythm is rare, as can be easily demonstrated by taking the pulsations 

 frequently, the irregularity being well marked in very young or old 

 animals. In normal conditions the pulse must be similar in both thighs. 



We find a lessening in the pulse in some forms of poisoning, fol- 

 lowing hemorrhages, in affections of the muscle of the heart, in starvation, 

 diseases of the brain, meningitis, in hepatogenous icterus, also in collapse 

 and in diseases characterized by a continued high temperature. 



An increase of the pulse is found in all fevers, in cases of valvular 

 defects, in heart w*eakness and paralysis or collapse of that organ from 

 continued high fever. When the temperature increases the pulse rises. 

 The pulse is irregular (arhythmic) in some diseases of the heart (in- 

 compensated valvular defects, myocarditis) after large doses of digitalis, 

 and in heart weakness. It is only intermittent (as a forerunner of 

 entire irregularity) in slight cases of valvular defects, in some diseases 

 of the brain, and in gastricism. The pulse is full and bounding under 

 great physical exertion, small and collapsed after severe hemorrhage 

 and in enteritis. In intense heart weakness and collapse it becomes 

 thread-like and imperceptible. 



The venous pulse — that is, the apparent increase in the amount 

 of l)lood in the jugular at its entrance into the chest — is often seen in 

 the dog. It is generally a symptom of some chronic heart affection, such 

 as imperfect closing of the tricuspid valves, and of heart weakness. 



DISEASES OF THE HEART. 



Acute Endocarditis. Endocarditis Verucosa ; Endocarditis Ulcerosa. 



Etiology. — This disease is comparatively rare. Jensen ropoi'ts 

 that ovit of a clinic of 3,240 dogs, he found 13 with ulcerative endocardi- 

 tis. This condition may be caused by a sympathetic irritation of myo- 

 carditis or mediastinitis, but this is extremely rare, it being caused by 

 the presence in the blood of certain microorganisms which lodge on the 

 endocardium, particularly in the vah^es and the deeper portions between 

 the trabecule, causing inflammation of the tissues. Endocarditis can 

 l)e produced experimentally by the introduction into the blood of vari- 

 ous forms of bacteria (staphylococcus, streptococcus, etc.) particularly 



