Canine Endocarditis - What Is It?

Endocarditis is a heart condition that comes about as the result of a fungal or bacterial infection that affects the heart’s valves. Endocarditis is not one of the most common of all canine heart conditions, but it does tend to affect certain types of dogs more than others, and because it is less commonly identified than other heart problems such as murmurs, it is frequently misdiagnosed or not properly diagnosed until it is quite advanced.

The ultimate fatality rate of endocarditis is high in the advanced stages of the condition, and this, accompanied by the fact that it is often overlooked or misdiagnosed in general practice veterinary clinics, means that it is wise for all dog owners to gain a basic understanding of the condition, its symptoms, and how it occurs.

Read on to learn more about canine endocarditis.

What causes endocarditis in dogs?

Endocarditis may develop as a secondary issue accompanying either a bacterial or fungal infection, although not many dogs that develop a minor form of such an infection will go on to develop endocarditis.

Endocarditis itself develops when the infection present becomes systemic after entering the bloodstream. As the blood carries the infection around the body, it deposits inside the heart’s valves, which leads to inflammation of the valves themselves and a decrease in the natural functions of the heart. The mitral and aortic valves of the heart are both generally affected, while the tricuspid valve is rarely involved, for reasons that are currently unclear.

It is not always obvious when a cat has a systemic fungal or bacterial infection, and sometimes, the underlying infection itself will only be diagnosed as a result of the dog being checked over and tested due to their decreased heart function. Due to the fact that the heart’s valves are of course responsible for circulating blood around the entire body, the infection will also pass to the other major organs too, potentially affecting how well they function as well.

When an infection such as a bacterial or fungal infection enters the dog’s body, the body’s immune system will attack the infection itself, and try to eliminate it. However, the immune system of very young dogs, older dogs and those whose immune systems are compromised may be weaker than most, and this can make infections easier to catch and harder to manage.

Endocarditis is more likely to occur in dogs of this type than others, and is most common in male dogs over the age of four, although female dogs and younger dogs can also be affected. Large breeds are more prone to the condition than others, with three breeds that tend to fall into the higher risk bracket including the Golden retriever, Labrador retriever, and German shepherd.

The symptoms of endocarditis in dogs

Once endocarditis develops, it becomes symptomatic fairly fast, as a heart dysfunction of course affects many of the other bodily systems as well. Some of the main symptoms to watch out for include:

• Lack of tolerance for exercise and loss of usual stamina.


• Shortness of breath.


• Fatigue and general weakness.


• Rapid, pronounced weight loss.


• A dry, unproductive cough.

Diagnosing endocarditis in dogs

The underlying infection that leads to endocarditis causes the heart itself to become enlarged, and so an ultrasound examination and x-ray will usually reveal the enlargement. Prior to this stage, routine blood tests may be used to identify the elevated white blood cell count that indicates an infection, and a combination of the symptoms presented and diagnostic testing will generally narrow down the potential problems to either confirm or rule out endocarditis.

An electrocardiogram or cardiac ultrasound examination may be performed as well.

Can endocarditis be treated?

If endocarditis is diagnosed early enough, it may be treatable with antibiotics, prior to a significant enlargement of the heart’s valves and damage to other organs occurring. If the condition has also lead to an abnormal heart rhythm, anti-arrhythmic medications may be used as well to correct this.

However, if the progression of endocarditis is already quite pronounced by the time it is formally diagnosed, the chances of successful treatment become much smaller. The involvement of other bodily organs greatly complicate the successful treatment of and recovery from endocarditis, and if congestive heart failure has begun, the prognosis for affected dogs is very poor.

If you know or suspect that your dog has developed a fungal or bacterial infection, or is showing any minor signs of ill health that might indicate this, get the checked out by a vet as soon as possible, as early intervention and treatment of the infection can prevent endocarditis from developing.

It is important to remember that bacterial or fungal infections rarely lead to endocarditis in dogs, and so this is a worst case scenario type of situation, but if your dog has a compromised immune system or is mature or very young, or if they are one of the at-risk breeds, you should be particularly vigilant.