464 HEALTH AND DISEASE 



MYOCARDITIS, OR INFLAMMATION OF THE MUSCULAR 

 STRUCTURE OF THE HEART 



This disease occurs very rarely in the lower animals, and most probably 

 when it does happen it is connected with other diseases which have been 

 described, i.e. pericarditis and endocarditis, in both of which the inflamma- 

 tion may extend to the muscular structure. 



Continental writers refer to myocarditis as an infectious disease associ- 

 ated with aphthous fever, septicaemia, tuberculosis, and contagious pneumonia 

 of the horse. 



The alterations which are occasioned in the muscular structure will 

 depend upon the activity of the inflammatory condition. Among them 

 may be mentioned softening, and different degrees of degeneration, which 

 weaken and impair the functions of the organ. 



In its chronic form the disease tends to the development of hypertrophy 

 or enlargement, hardening of the muscular structure, and diff'erent forms 

 of fatty and fibroid degeneration, and in some instances small abscesses are 

 formed in the muscular walls. 



Symptoms of myocarditis are not of a sufficiently definite character to 

 lead to a correct diagnosis. In the majority of cases the pulse is weak, 

 sometimes hardly detectable, generally increased in frequency, and the 

 respiration is rapid and carried on with difficulty. Sometimes, when caused 

 to turn, the animal grunts, and deep pressure over the region of the heart 

 causes pain. There is also weakness, incapacity for work, a fastidious 

 appetite, and occasional attacks of vertigo, especially in the advanced forms 

 of the disease. There is an absence of the morbid sounds which are 

 observed in cases of pericarditis and endocarditis, and in valvular disease. 



DISEASES OF THE VALVES OF THE HEART 



Endocarditis in the chronic form may be expected to lead to a certain 

 alteration in the valves which guard the openings leading to and from the 

 different cavities of the heart. The alterations of structure may consist of 

 thickening of the valves, adhesion of one to the other at their edges in 

 particular, and to the walls of the cavities. In some cases they develop 

 large excrescences, or, as they are sometimes called, cauliflower growths, 

 which occupy a considerable space in the cavities of the auricles or 

 ventricles. (See Coloured Plate.) Among the domestic animals the pig 

 appears to be most subject to these growths, which have been constantly 

 found in the post-mortem examinations of animals which have died or been 

 slaughtered in consequence of swine fever. 



