DISEASES OF THE HEART AND BLOOD, ETC. 355 



fess entire ignorance. Among the hundreds of horses that 

 we have examined and dissected, we have never discovered 

 any preternatural symptoms in the tissues of that organ. It 

 is only fair to say, however, that these examinations were di- 

 rected to some other end than critically investigating the sub- 

 ject of heart disease. 



Youatt enumerates eight different diseases of this class, and 

 attempts to give specific symptoms in each case. But we 

 see no essential differences in his descriptions of them, save 

 merely in their verbal arrangement. He makes no pretensions 

 to giving any remedy for them. Hardly any other recognized 

 authority makes any mention of the horse suffering from 

 heart disease. 



Although it is quite reasonable to suppose that so vital a 

 part of the animal's organism may be the seat of various 

 disorders, it will be of no consequence to the farmer to spend 

 much time in considering the subject, unless some remedy 

 can be suggested ; and as this is beyond our power, we may 

 as well dismiss the whole matter and pass on to something 

 else. 



THUMPS. 



This is a not uncommon disease in many*sections, having 

 its origin, not in the heart, yet very near it, in the pulmonary 

 artery, (See E, in preceding cut.) It is a cartilaginous en- 

 largement of the walls of that vessel, so that the channel be- 

 comes diminished in size, and can not pass the same quantities 

 of blood that it does in its healthful state. When it is con- 

 sidered that every drop of blood in the entire circulation is 

 propelled through this main duct, on its passage from the 

 right ventricle of the heart to the lungs, there to be arteri- 

 al ized or purified, it becomes apparent^ at once, that any 

 obstruction of the pulmonary artery must cause serious dis- 

 turbance in the heart, whose contractions are the power that 

 forces the blood along this channel. 



The pulmonary artery, like every other in the body, is 

 composed of three distinct coatings — the outer, or perito- 

 neal; the middle or muscular; and the inner, or serous. Its 



