CHRONIC ENDOCARDITIS: VALVULAR ALTERATIONS, 471 



CHRONIC ENDOCARDITIS: VALVULAR 

 ALTERATIONS. 



Etiology. Valvular diseases are extremely common in our 

 domestic animals, especially in the horse and dog. In the majority 

 of cases they are characterized by alterations which are developed 

 in the course of chronic endocarditis, which most often succeeds 

 acute endocarditis. In the ox they are ordinarily preceded by acute 

 articular rheumatism, which is complicated by cardiac accidents 

 (Hering, Joyeux). In the horse they have been observed after 

 influenza (Percival), and in some other acute infectious diseases. 

 Chronic endocarditis recognizes another pathology in which colds, 

 repeated excitements, and violent exertions play the principal rôle. 

 Processes of arterio-sclerosis which develop at the origin of the 

 large bloodvessels (Boisy) also give rise in old animals to valvular 

 alterations. These may also be produced during intra-uterine life; 

 in cases of this kind and in a certain number of others, we must 

 admit a congenital predisposition. 



They are exceptionally related to anomalies of development and 

 to neoformations. Johne and Eisenblatter have described con- 

 genital alterations of the inter-ventricular wall in the cow. In a 

 dog affected by epileptiform attacks and cyanosis, Franck has found 

 an incomplete obstruction of BotaPs canal. Neoplasms of the heart 

 and those which are developed in its neighborhood (carcinoma, sar- 

 coma, myxoma), hypertrophy or tumors of the bronchial ganglions 

 (Johne, Koch, Wolff) may produce contractions of the cardiac 

 orifices. But recorded facts of this kind are very rare ; we shall 

 therefore limit ourselves to the study of valvular affections produced 

 by chronic endocarditis. 



Patholog-ical anatomy. The alterations of the auriculo- ven- 

 tricular and sigmoid valves determine the insufficiency or the con- 

 traction of the corresponding opening.^ 



Insufficiency of the valves is due to their contraction or shortening 



^ Valvular endocarditis as a first effect produces a want of coaptation of the valvu- 

 lar blades — that is to say, an insufficiency. As the process never rétrocèdes, the valves 

 undergo a double retraction : first, along the vertical axis— that is to say, the free edge 

 toward the investing line ; secondly, along the transversal axis or in the direction of 

 the loose edge. This progressive retraction of the valves increases little by little the 

 insufficiency, and ends by leading to the contraction of the corresponding orifice. 

 Valvular insufficiency is thus the first term of a lesion the last stage of which is con- 

 traction (Peter). — n. d. t. 



