endocardium

Canine Heart Problems

HEART problems can arise as part of the ageing process. A heart is a muscular organ and just as in humans, the dog's heart can start to weaken with age.

Endocarditis

This is where the endocardium of the heart becomes inflamed and also there is damage caused to the heart valves. Luckily it's not a very common cause of heart disease in the dog. It is not necessarily a disease of ageing as the cause is usually a bacterial infection.

The symptoms of endocarditis are shortness of breath, poor appetite and apparent depression as well as a slight fluctuating temperature. The dog usually seems listless, easily puffed and disinterested.

Bacteraemia is probably the most common source of cardiac infection, arising from dental disease and dental work, infections of the urogenital tract, prostate, skin, bone, lung and intestine. The more commonly reported organisms causing endocarditis in dogs are: Staphylococcus spp, Escherichia coli, Corynebacterium spp and Pseudomonas aeruginosa

Treatment requires identification of the infective organism an control of the symptons of heart failure. The use of antibiotics while waiting for bacterial culture is recommended. It is important to remember to treat any other extra-cardiac infection.

Prognosis is poor, with most cases dying from congestive heart failure, dysrhythmias, sepsis or renal failure.

Myocarditis

Poisoning by certain metals or certain infections can cause disease to the myocardium or heart muscle itself. The myocardium can become enlarged. Inflammation of the myocardium is called myocarditis and is usually caused by an infection. Definitive diagnosis of myocarditis is rarely made in animals as it requires myocardial biopsy or post-mortem examination. The symptoms of this disease are exhaustion and difficulty breathing during even small amounts of exercise.
There are, however, some recognised causes of myocarditis in dogs.

Lyme carditis
Lyme disease is caused by the tick-borne agent Borrelia burgdorferi (borreliosis) resulting in fever, lethargy, anorexia;
acute lameness, swollen painful joints; skin lesions associated with the tick bite; lymphadenopathy; heart block and endocarditis. Diagnosis is based on identifying a rising antibody titre and can be effectively treated with tetracyclines or penicillins.

Canine parvovirus
Usually found in young puppies (3-10 weeks old). The symptoms can resemble DCM, and the prognosis is poor, usually being fatal.

Trypanosomiasis (Chagas' disease)
Chagas' disease is a protozoal infection (Trypanosoma cruzi) occurring in the southeastern USA, Central and South America and Africa. It is primarily a disease of dogs under two years old, and can present in both an acute and a chronic form. Clinical signs are referable to an infectious process and CHF. Diagnosis requires demonstration of parasitaemia by culture, xenodiagnosis or serodiagnosis.

Ischaemic heart disease
Whereas coronary atherosclerosis is the most common form of heart disease it is very rare in dogs and cats. However, coronary embolism may occur secondary to infective endocarditis or the aortic valve, septicaemia or pulmonary neoplasms.

Physical injury
Physical injury to the heart may arise from trauma (traumatic myocarditis), e.g. road traffic accident, heat stroke or electric shock. Although other lesions may be more obvious, undetected cardiac trauma may result in death 12-24 hours after the trauma.

Pericarditis

The pericardium is a fibrous sac which surrounds the heart, separating it from the lungs, and its function is mechanical. The heart can function normally in the absence of the pericardium, but operates more efficiently if it is present. It acts as a barrier to infection and allows free movement of the heart within the thoracic cavity.

Pericarditis is where the heart sac becomes inflamed because of an infection like influenza or pleurisy. The dog will be weak and the vet will notice a change in her/his pulse.

Mitral valve dysplasia

This is a deformity of the valve which causes blood to regurgitate at each beat into the left atrium from the valve cusps.
There are certain breeds which have a tendency for this - German shepherds, great Danes, cavalier King Charles spaniels and bull terriers.

Diseases affecting the mitral valve complex include Endocardiosis and rupture of the chordae tendineae. Congenital mitral valve dysplasia. bacterial endocarditis.

Incompetence secondary to: cardiomyopathy; congenital shunts leading to left atrial dilation and volume overload, e.g. VSD or PDA.

Diseases of the tricuspid valve complex include Endocardiosis. Congenital tricuspid valve dysplasia. Bacterial endocarditis (very rare). Heartworm disease Very rare congenital anomalies - Epstein's anomaly, ventricular canal defect.

Incompetence secondary to: cardiomyopathy; pulmonic stenosis advanced patent ductus arteriosus (PDA) or a ventricular septal defect (\/SD). tricuspid atresia, atrioventricular

The above information is simply informational. It's intent is not to replace the advice of a veterinarian nor to assist you in making a diagnosis of your pet. Please consult with your own veterinarian for confirmation of any diagnosis. Your pets life may depend on it.