Understanding Dilated Cardiomyopathy (DCM) in Dogs

Dilated cardiomyopathy, or DCM, is a serious heart condition where the heart muscle weakens and enlarges, making it harder for the heart to pump blood effectively. It’s the second most common heart disease in dogs, and one of the most challenging to catch early because it often develops without obvious symptoms. If your dog has just been diagnosed, or you’re trying to understand what to watch for, this article covers what you need to know.

What is dilated cardiomyopathy (DCM)?

DCM is a disease of the heart muscle that causes the heart to enlarge and makes it progressively harder to pump blood through the body. Over time, the heart’s ability to distribute oxygen-rich blood decreases, which can lead to symptoms like fatigue, breathing difficulties, or even sudden collapse.

One of the trickiest aspects of DCM is its silent phase, called the occult stage. During this phase, the heart is already under strain, but your dog might not seem sick at all. When symptoms finally appear, the condition has often progressed significantly, which is why early screening for at-risk breeds is so important. Catching it early can be lifesaving.

Symptoms of dilated cardiomyopathy

The signs of DCM can vary, but here’s what to keep an eye on:

• Low energy levels or exercise intolerance, your dog tires easily during play or walks.
• Coughing or labored breathing, often caused by fluid buildup around the lungs.
• A bloated abdomen due to fluid accumulation.
• Sporadic fainting or sudden collapse, which might indicate heart arrhythmias.
• In advanced cases, rapid or heavy breathing, a blue tongue, or excessive drooling

DCM may have a sudden onset of clinical signs, and some dogs may develop severe congestive heart failure in only a few hours. Rapid, heavy breathing, a blue tongue, excessive drooling, or collapse may be the first signs. If you notice any of these, get to a vet immediately.

What causes DCM in dogs?

Several factors can play into why a dog develops DCM, and in many cases, the exact cause is unknown. Some of the most common links include:

• Genetics: Breeds like Dobermans, Great Danes, Boxers, and Golden Retrievers are more prone to DCM.
• Taurine deficiency: Linked to grain-free diets, though research is ongoing. Taurine is essential for heart health.
• Infections or inflammation: Certain infections or autoimmune conditions may impact the heart muscle.
• Hypothyroidism: Low thyroid hormone levels can weaken the heart.
• Medications: Some chemotherapy drugs may contribute to DCM progression.

If your dog’s breed is at higher risk or has been on a grain-free diet, it’s a good idea to bring it up with your vet to discuss screening and dietary adjustments.

How is DCM diagnosed?

Diagnosing DCM typically involves several tests aimed at understanding your dog’s heart function. Here’s what the diagnostic process might include:

• Chest X-rays: These can show signs of enlarged heart or fluid buildup in the lungs.
• Echocardiogram: A detailed ultrasound of your dog’s heart that provides a clear image of how it’s functioning – often the definitive test for DCM.
• Holter monitor: This wearable device records your dog’s heart rhythm over a 24–48-hour period, especially useful for arrhythmias.
• Blood tests: Checking overall health and taurine levels if a deficiency is suspected.

For breeds with a higher genetic risk, screening is often recommended before symptoms ever appear. Veterinarians may recommend screening tests for predisposed breeds to detect DCM sooner, which can improve their prognosis. It’s worth asking your vet about screening if your dog is one of the breeds listed above.

How is DCM treated?

There’s no cure for DCM, but treatment focuses on improving your dog’s quality of life and slowing disease progression. Your vet may recommend:

• Pimobendan: A medication that strengthens the heart’s ability to pump blood effectively.
• ACE inhibitors: Help relax blood vessels, reducing the heart’s workload.
• Diuretics: These manage fluid buildup in the chest or abdomen.
• Antiarrhythmics: Help regulate abnormal heart rhythms.
• Taurine supplements: If your dog has low taurine levels.
• Dietary changes: if diet-associated DCM is suspected, switching away from a high-legume diet is usually one of the first recommendations, and in some cases dogs have shown improvement after dietary changes

In some cases, lifestyle changes, like moderate exercise and a heart-friendly diet, may also be recommended. Treatment plans depend on your dog’s specific condition, so tailored care is key.

Does pet insurance cover DCM?

The short answer is yes. If your dog develops DCM after your Lemonade Pet policy is active and your waiting periods have passed, it can be covered under illness coverage. Managing DCM isn’t a one-time cost: regular echocardiograms, specialist visits, and long-term medications all add up, and a base accident and illness policy covers the diagnostics, treatments, and medications involved. You can also build out your coverage to match your dog’s needs. The Visit Fee add-on means exam fees from follow-up and specialist visits are covered alongside everything else.

For breeds with a genetic predisposition to DCM, the earlier you get coverage in place, the better. Once a condition is on your dog’s medical record, it’s usually considered pre-existing and can’t be covered. Don’t wait for symptoms to appear.

Before we go

A DCM diagnosis is serious, and it’s okay to feel overwhelmed by it. But staying informed and working closely with your vet puts you in the best possible position to help your dog. If your dog is showing any of the symptoms mentioned, or if they’re a breed with a known predisposition, don’t wait to bring it up with your vet. Early detection can make a meaningful difference, and having the right support in place, including pet insurance, means one less thing to worry about when it counts.

Frequently Asked Questions

A few quick words, because we <3 our lawyers: This post is general in nature, and any statement in it doesn’t alter the terms, conditions, exclusions, or limitations of the policies issued, which differ according to your state of residence. You’re encouraged to discuss your specific circumstances with your own professional advisors. The purpose of this post is merely to provide you with info and insights you can use to make such discussions more productive! Naturally, all comments by, or references to, third parties represent their own views, and Lemonade assumes no responsibility for them. Coverage may not be available in all states. Please note that statements about coverages, policy management, claims processes, Giveback, and customer support apply to policies underwritten by Lemonade Insurance Company or Metromile Insurance Company, a Lemonade company, sold by Lemonade Insurance Agency, LLC.  The statements do not apply to policies underwritten by other carriers.