Endocarditis in Dogs: What Is It and Is It an Emergency?

Endocarditis in dogs occurs when bacteria attach to the inner lining of the heart, including the valves. It is a relatively uncommon condition, but it can cause serious complications in affected dogs. 

Here we will discuss everything you need to know about endocarditis in dogs, including what causes it, how it’s diagnosed, and what treatment options are available. 

What Is Endocarditis in Dogs?

Endocarditis in dogs refers to infection of the inner lining of the heart, the endocardium, and most commonly involves one or more heart valves.  

Bacteria enter the bloodstream and can attach to the endocardium or heart valves, causing inflammation and damage that interferes with normal heart function. 

Affected dogs may experience fever, weight loss, lethargy, and decreased appetite in the early stages. If left untreated, endocarditis can progress to heart failure and cause signs such as coughing and difficulty breathing. Not all dogs will progress to heart failure. This is dependent on which valve is affected, pre-existing health conditions, and when treatment is initiated. 

Endocarditis can become life-threatening and requires prompt veterinary treatment because it may cause severe valve damage, heart failure, arrhythmias, or infection-related complications in other organs.  

If you notice concerning symptoms in your dog, contact your veterinarian promptly.  

Symptoms of Endocarditis in Dogs

Symptoms of endocarditis in dogs may include:  

• Fever 
• Weight loss 
• Lethargy 
• Decreased appetite 
• Heart murmur 

If endocarditis causes heart failure, you may notice additional symptoms, such as: 

• Shortness of breath 
• Rapid breathing 
• Coughing 
• Blue-tinged gums (cyanosis)  
• Swollen belly 
• Exercise intolerance 
• Generalized weakness 

Causes of Endocarditis in Dogs

The most common cause of endocarditis is a bacterial infection.  

When bacteria enter the bloodstream, they can travel to the heart and attach to the heart valves or other endocardial surfaces.  

This most commonly occurs when heart valves have been previously damaged, such as due to a congenital heart defect or prior surgery. However, endocarditis can also affect normal heart valves.  

Bacteria causing endocarditis may originate from infections elsewhere in the body, including the urinary or reproductive tracts, skin, or mouth.   

Endocarditis is relatively uncommon in dogs overall; however, some types of dogs have an increased risk for the condition, including:  

• Dogs with certain pre-existing heart conditions, such as subaortic stenosis 
• Middle-aged, large-breed dogs  
• Males 
• Dogs with weakened immune systems  

How Veterinarians Diagnose Endocarditis in Dogs

To diagnose endocarditis, a veterinarian will do a physical exam, take a thorough history, and order testing. They will want to know what symptoms are present, when symptoms began, and what medications, if any, your dog is currently taking.  

To start, your vet will perform a complete physical exam, paying close attention to your dog’s breathing, gum color, and heart rate and rhythm. If an underlying heart issue is suspected, testing may include:  

• Blood work: A small sample of blood is used to check blood cell counts, organ function, and electrolyte status.  
• Urinalysis: A sample of urine can be used to identify infection, inflammation, and protein loss.  
• Blood culture: Blood samples are sent to a laboratory to identify bacteria in the bloodstream and determine which antibiotics are likely to be effective. Multiple samples may be collected because blood cultures can sometimes be negative even when endocarditis is present. 
• X-rays: Images of the chest and abdomen can show heart enlargement and signs of heart failure, such as fluid in the lungs or belly.  
• Electrocardiogram: An ECG may be done to check for heart rhythm abnormalities.   
• Echocardiogram: Echocardiography is the diagnostic test of choice because it allows the veterinarian to evaluate the valves for characteristic thickening while assessing heart function in real time.  

Treatment of Endocarditis in Dogs

Treatment of endocarditis focuses on controlling symptoms, treating the infection, and reducing inflammation. Treatments that may be prescribed include:  

• Antibiotics: Dogs are typically started on broad-spectrum antibiotics while blood-culture results are pending. Depending on the suspected bacteria and culture results, antibiotics such as enrofloxacin or ampicillin may be prescribed. 

• Diuretics, such as furosemide: These may be prescribed if congestive heart failure causes fluid buildup. 

• ACE inhibitors, such as enalapril: These may be used in some dogs with heart failure to improve heart function and lower blood pressure.

• Inodilators, such as pimobendan: These may be used to help support heart function in dogs who develop heart failure.  

• Hospitalization and supportive care: Dogs with severe illness may require hospitalization, oxygen therapy, intravenous fluids, treatment of arrhythmias, and other supportive care.  

Endocarditis in dogs is not curable in every case. 

 It can cause irreversible valve damage and secondary complications such as heart failure. Prompt diagnosis and treatment are important for the best possible outcome. 

Recovery and Management of Endocarditis in Dogs

Prognosis depends on the severity of symptoms and how advanced the disease is at the time of diagnosis. Dogs in a severe condition with multiple affected heart valves have a poor prognosis despite treatment. If symptoms are mild, especially if only one heart valve is affected, treatment is much more effective and there is a more favorable outcome.   

Antibiotic treatment is typically prolonged. Dogs may initially receive injectable antibiotics for one to two weeks, followed by oral antibiotics for at least six to eight weeks, depending on the infection and response to treatment.  

Lifelong medical management may be needed if irreversible damage to the heart has occurred or if a dog develops chronic heart failure.  

Prevention of Endocarditis in Dogs

Not all cases of endocarditis are preventable, but pet parents can take steps to support overall health and reduce some risk factors:  

• Ensure your dog receives regular veterinary care to identify and manage health concerns early.  
• Effectively manage any underlying health conditions by following your veterinarian’s recommendations. 
• Maintain good dental health with regular at-home dental care and professional cleanings as recommended by your veterinarian.