Persistent atrial standstill, a form of cardiomyopathy Overview of Cardiomyopathy in Dogs and Cats Cardiomyopathy is defined as a primary disease of the myocardium. Most of the cardiomyopathies of animals are idiopathic diseases that are not the result of any systemic or other primary cardiac... read more resulting in destruction of the atrial myocardium (which may also affect the ventricular myocardium), has been reported in dogs. Affected breeds include English Springer Spaniels, Old English Sheepdogs, Shih Tzus, German Shorthaired Pointers, and mixed-breed dogs. The disease has also been reported in some cats with concurrent cardiomyopathy. Initially, atrial myocardial destruction leading to atrial standstill (no atrial electrical or mechanical activity) and an atrioventricular nodal escape rhythm is noted. Mitral regurgitation Mitral Valve Dysplasia in Animals Mitral valve dysplasia is a congenital malformation of the mitral valve leaflets or any other component(s) of the mitral valve complex. This condition occurs in dogs and is a common defect of... read more that may be severe often occurs at this stage. Eventually, myocardial failure may ensue. Clinical signs are similar to those in animals with dilated cardiomyopathy Dilated Cardiomyopathy in Dogs and Cats Dilated cardiomyopathy (DCM) is characterized by the progressive loss of myocyte number and/or function, along with a decrease in cardiac contractility. DCM is most prevalent in dogs and is... read more , with right heart failure Right Heart Failure The three primary functions of the cardiovascular system are to maintain 1) normal blood pressure and 2) normal cardiac output, both at a 3) normal venous/capillary pressure. Heart failure is... read more 
or left heart failure Congestive Heart Failure (Left Heart Failure) The three primary functions of the cardiovascular system are to maintain 1) normal blood pressure and 2) normal cardiac output, both at a 3) normal venous/capillary pressure. Heart failure is... read more being noted. Pacemaker implantation may improve heart rate and cardiac output. Other treatment aims to palliate clinical signs of CHF.
