Canine Bacterial Endocarditis: Symptoms and Considerations

Bacterial endocarditis in dogs is a serious infection affecting the inner lining of the heart (endocardium), often involving the heart valves. While the history of the disease is often vague, its manifestations are more akin to a systemic infection rather than a purely cardiac one. The clinical presentation is highly variable, depending on the extent of the infection and the organs involved, often reflecting impaired valve function. Early diagnosis and treatment are crucial for a favorable outcome.

Symptoms:

The symptoms of canine bacterial endocarditis are diverse and non-specific, making diagnosis challenging. They can range from subtle lethargy to severe life-threatening complications. It’s essential to remember that not all dogs will exhibit all symptoms, and the severity of symptoms varies depending on several factors, including the infecting organism, the extent of the valvular damage, and the individual dog’s immune response.

Early Stage Symptoms (Often Subtle):

Lethargy and Anorexia: A decreased energy level and loss of appetite are common early signs. The dog may seem less playful and more inclined to rest.

Weight Loss: Unexplained weight loss, even with a seemingly normal appetite, can be an indicator.

Intermittent Fever: Occasional, low-grade fevers may be present, often going unnoticed until more pronounced symptoms develop.

Subtle Limping or Joint Pain: Mild lameness or joint discomfort, potentially due to microemboli, may be observed. The dog might not show significant limping but could exhibit subtle signs of discomfort when touched in certain areas.

Late Stage Symptoms (More Pronounced):

Cardiac Murmur: A heart murmur, which may vary in intensity and timing (systolic or diastolic), can develop as the infection progresses and affects valve function. This is often a late sign and warrants immediate veterinary attention.

Arrhythmias: Irregular heartbeats (arrhythmias) can occur due to direct damage to the heart muscle or the effects of emboli (blood clots). These arrhythmias can be life-threatening.

Congestive Heart Failure (CHF): As the heart’s function deteriorates, signs of CHF may appear, including coughing (especially at night), difficulty breathing, and fluid accumulation in the lungs or abdomen (ascites).

Neurological Signs: Emboli can travel to the brain, causing neurological signs such as seizures, disorientation, or changes in behavior.

Musculoskeletal Symptoms: Infection can spread to the joints, causing septic polyarthritis (inflammation of multiple joints) with pain, swelling, and lameness. Non-suppurative (non-destructive) immune-mediated polyarthritis can also occur due to immune complex deposition in the joint lining.

Renal Issues: Emboli can affect the kidneys, potentially leading to kidney dysfunction.

Other Systemic Signs: Symptoms such as pallor (pale gums), petechias (small pinpoint hemorrhages under the skin), or other signs of systemic illness can be present. Increased thirst and urination (polydipsia/polyuria) may also be observed.

Differential Diagnoses:

The non-specific nature of the symptoms makes it crucial to consider other conditions that could mimic bacterial endocarditis. These include:

Other Infectious Diseases: Several infections can cause similar symptoms, including viral infections, Lyme disease, ehrlichiosis, and Rocky Mountain spotted fever.

Cardiomyopathy: Diseases of the heart muscle itself can cause similar clinical signs.

Valvular Disease (Non-infectious): Degenerative valvular disease can produce murmurs and lead to heart failure.

Immune-mediated Diseases: Autoimmune disorders can affect the joints and cause lameness.

Diagnostic Testing:

Diagnosis requires a combination of physical examination, blood work (including a complete blood count and blood chemistry profile), electrocardiography (ECG), echocardiography (ultrasound of the heart), and potentially blood cultures to identify the causative bacteria. Imaging techniques may also be necessary to assess the extent of the damage to heart valves and other organs.

Treatment:

Treatment of bacterial endocarditis is crucial and requires long-term administration of appropriate antibiotics. The specific antibiotic regimen depends on the identified pathogen and its susceptibility. Treatment typically involves intravenous antibiotics for several weeks, followed by a period of oral antibiotics. Supportive care, including management of heart failure and pain, may also be necessary. In severe cases, surgical intervention may be considered to repair or replace damaged valves. The prognosis depends on the severity of the disease, the effectiveness of treatment, and the presence of complications. Early diagnosis and prompt treatment significantly improve the chances of a positive outcome. Regular veterinary check-ups are essential for monitoring the dog’s condition and preventing recurrence.