Enlarged Heart in Dogs: Dilated Cardiomyopathy Explained

A dog fills our hearts with joy and asks for nothing in return. However, we are the ones who should take care of its heart, especially in case there is something wrong with it. Since a dog cannot describe its symptoms, only its owner can observe it and try to identify what is not right or what has changed in its behavior.

When it comes to heart diseases, enlarged heart in dogs is among the most possible conditions that may occur. An informed dog owner can easily learn to recognize the occurrence of dilated cardiomyopathy in his or her dog and act in a timely manner before the affection aggravates or evolves in any way.

As heart is for humans, so is for dogs. It is the most important muscle from their bodies, the core that keeps them alive and which can become life threatening if it starts malfunctioning. Heart diseases in dogs are most often caused by the malfunction of the valve or the heart muscle, also called myocardium.

If your dog suffers from a heart disease, its body retains more salt than needed and more water as well. This affection is also called hydro-saline retention, characterized by situations when fluid can accumulate in a dog’s lungs or abdomen resulting in shortness of breath and abdominal pain. If a pooch’s heart does not work like a well-oiled engine, then its blood circulation is slowed down and leads to fatigue, weakness and other symptoms.

Alike humans, the types of heart diseases in dogs can be hereditary or they can occur at some point in their lives. Most often, a heart disease occurs because of different reasons, affecting older dogs preponderantly. This article on how to take care of senior dogs can help you a lot, so check it out.


There are 2 types of heart diseases in dogs that are most met. The first type is when a dog’s heart valves lose their ability to properly close, causing abnormal blood flow. The second type manifests when a dog’s heart muscles become thin and weak, being unable to sustain its function in a normal way. These are general affections that include the case when a dog’s heart is enlarged.

Dilated cardiomyopathy is a cardiovascular disease, potentially fatal, characterized by the dilatation of the heart, both of its left and right sides. However, the coronary vessels and atrioventricular valves do not show changes, but there is a myocardial dysfunction present mainly in the systole. In other words, if your dog has a big heart in the most literally way possible, that is rather a bad thing than a positive one. A dog with such affection has a bigger heart and as it gets even bigger, its heart muscles get thinner and consequently its heart gets weaker.

Therefore, its heart has a weaker ability to push the blood throughout its body.

According to a study made by specialists, this type of heart disease occurs in dogs aged between 4 and 11 years. They are mostly males than females and they belong to dog breeds such as Doberman, Boxer, German Dog, Afghan, and Cocker, among others. Their respiratory, excretory, and circulatory systems started to malfunction, thus determining veterinarians to take further tests and establish a correct diagnosis, which was dilated cardiomyopathy.

Besides the clinical exam, there are numerous tests that must be done in order to establish for sure the affection that generates the symptoms present in certain dogs that may or may not be predisposed to developing heart diseases.

Symptoms of Dilated Cardiomyopathy

A responsible and informed dog owner can easily observe the symptoms of heart disease in his or her dog. A sick dog should start breathing faster and to coughing heavily. Of course, a proper consultation by a specialist can reveal a lot more, such as pulmonary edema, weight loss, lethargy, tachycardia or fibrillation, hepatomegaly, increased capillary refill time and so on. Out of all the complications that can occur, the most important complication is pulmonary edema, which means there is water in the dog’s lungs.

Edema occurs in a dog’s lungs because its blood stagnates more than usual in a place where it can be absorbed, namely the place where oxygen passes into the blood. When that happens, a dog can barely breathe and it has the feeling of suffocation.


In some cases, heart failure develops suddenly, for example after a viral infection, or progressively. Progressively developed symptoms of heart failure may include weakness, fatigue, dyspnea that means difficulty in breathing, wheezing that refers to the whistling noise made by the passage of air through narrowed airways, shortness of breath, dry and irritating cough, swelling especially in the legs, dizziness, fainting, rapid weight gain caused by water retention, increased urination at night, abdominal swelling, tenderness or pain that can result from fluid retention in the body.

In addition, the symptoms present in case of a sudden heart failure are severe shortness of breath, fast or irregular heartbeat, mucous expectoration that can be pink. If a dog is not getting treatment, things can get complicated and generate pulmonary edema, hypoxia, cardiogenic shock, death, infective endocarditis, thromboembolism, venous thrombosis, cardiac cirrhosis, supraventricular and ventricular arrhythmias, which are abnormal heart rhythms that can cause loss of consciousness or sudden death.

Diagnosing Dilated Cardiomyopathy in Dogs

The detection of this disease is made by a veterinarian with the help of a chest radiographic examination, an electrocardiogram, and a Doppler echocardiogram or a simple one. The latter technique helps the doctor examine a dog’s heart from the morphological point of view, but also to determine the speed and direction of its blood flow. These tests are mandatory to rule out other diseases and determine the impact of the current one on the canine patient in question.

Tests may also include a complete medical history and a physical examination of the dog’s heart and lungs with a stethoscope. Heart murmurs, abnormal heart sounds, and irregular heart rhythms may indicate an existing problem in the heart.


Among the other possible tests are measuring a dog’s blood pressure, verifying the hematocrit levels or asking for a complete blood count. These tests may be needed in order to identify a possible state of anemia or other diseases such as infections or inflammations. In addition, the vet may request biochemical tests, which are particularly important in case of thromboembolism or other complications in other organs. Testing the thyroid hormone to exclude hyperthyroidism might also be necessary, just as a urinalysis to assess kidney function.

The coronary angiogram and coronary catheterization assumes the insertion of a thin tube through a flexible artery or vein to the heart, to measure the pressure in the heart chambers and to take blood samples. A dye can be injected to see if the arteries that supply the heart, called the coronary arteries, are blocked as the heart pumps blood or not.

As a last option, the specialist can ask for a myocardial biopsy, which involves taking a sample of the heart tissue and examine it for signs of infection, metabolic diseases or tumor. This procedure is usually reserved for patients with acute heart failure that are unresponsive to treatment.

Treatment for Dilated Cardiomyopathy in Dogs

A treatment for heart diseases in dogs may include a diet low in sodium, moderate exercising and the administration of drugs. Medications are used to strengthen heart contractions, eliminate fluid retention and dilate the blood vessels so blood can flow more easily through a pooch’s veins.

With the supervision of a veterinarian, some dogs can fully recover and resume their old habits, being as cheerful and as playful as they were before getting sick. However, these are rare cases and they might only apply for when heart enlargement is detected right after it starts and things don’t get complicated.

Besides salt retention and water retention in the body of a dog, another cause of heart disease can be obesity. The solution for that situation consists in a low fat diet recommended by a veterinarian, not taken from other sources. It is important for a dog’s food to taste good, because otherwise it will not eat it and it will lose weight by making itself starve, fact which can lead to the development of other nutritional diseases. Those problems might not be as serious as heart diseases are, but they cause trouble and they are unwanted in every imaginable way.

In general, the doctor prescribes medications that contain combinations of drugs, which help in the process of eliminating fluids, pumping blood better throughout the body and dilating blood vessels as well. Patients also receive salt restriction, certain inhibitors, diuretics and digitalis. In some situations, vets might also prescribe anticoagulants.

You should never give more or less drugs to your dog unless the vet recommends it. Taking a decision regarding your dog’s health should be limited to its lifestyle, not to its medication. Try not to overlook its dietary needs and give it treats thinking that makes it happy because it will not.

Treatment for Dilated Cardiomyopathy in Dogs

As soon as you bring your dog back home from the veterinary clinic, you should keep stress factors at minimum. A stressed dog will have to breathe faster and that will make its heart pump faster. Also, you should avoid strenuous activities and exercises in order to not overburden its heart.

Be extra careful to aspects like increased respiratory rate, shortness of breath, increased respiratory effort, profound anemia, lethargy and collapse. The medication recommended by the veterinarian should be given exactly. In case you notice something going wrong, take your doggy back to the vet before it is too late.

Preventing Dilated Cardiomyopathy in Dogs

Many types of heart diseases can be prevented or detected early in case of most dogs. There are certain things you can do for your dog in order to avoid heart diseases. Regular checkups at the vet and exercises are just some examples, as well as paying attention to it, feeding it properly and so on. There are many essential aspects that ensure a long and happy life for your dog. Moreover, some of the advices might work on you as well.

The principles of living a healthy life are not so different from man to dog or the other way around:

  1. The first step you can take in order to prevent heart diseases is to learn more about all the health issues present in dogs belonging to the same dog breed as the one you own. All dog breeds have cases of specimens that got sick during their lives or that were born with a congenital heart disease. Certain dog breeds may be more predisposed to certain types of heart diseases, abnormalities such as muscle diseases or cardiomyopathies or those related to the enlargement of the heart chambers because of a weak muscle.
    Electrical irregularities found on electrocardiograms or congestive heart failures can be treated if they are detected early. Dog breeds such as Cockers, Boxers and Doberman Pinschers are more prone to getting a heart disease.
  2. Feed your dog with foods rich in the following 2 important nutrients: L-carnitine and taurine. Taurine is an amino acid that can prevent a possible calcium overload and that is found in the heart muscle. L-carnitine is a kind of protein that feeds the heart. A diet poor in these nutrients could lead to heart disease. L-carnitine is found in red meat in high concentrations and in lower concentrations in vegetables and cereals. In addition, Omega-3 oils, cheese, eggs and meat contain large amounts of taurine. Find out more in our piece regarding the best nutrition for your dog.
  3. Use natural supplements to prevent heart disease in behalf of your dog. The Hawthorn plant can lower cholesterol, strengthens the heart and regulates blood pressure and heart rate. Gingko biloba, dandelion, parsley, ginseng, ginger and chili are very good for the heart and can be added to foods or given as supplements.
  4. Make sure to prevent Lyme disease, which can cause heart problems, by removing ticks and fleas. The Lyme disease is transmitted directly from ticks. Check to see if your dog has ticks on the surface of its body. There are collars, pills and ointments available to prevent ticks.
  5. Exercise with your canine pet for the health of its heart, but also for the health of your heart. Keep your dog in an ideal shape by exercising diversely, such as walking, running, playing and swimming.
  6. Carefully and closely watch your dog in order to notice a possible shortness of breath or other breathing problems during exercising sessions and during sleep as well. If it starts to cough, note how often it does that and what is it doing while and after coughing. Dogs that cough during the night may have congestive heart problems.
    Coughing during meals may be a sign of esophageal obstruction. Heart disease can cause coughing during exercise or excitement. Take your dog for a routine examination whenever you think it is necessary and keep accurate records that can help the veterinarian in the process of setting a diagnosis.
  7. Administer medication in order to prevent heartworm. A monthly supplement or an ointment that can be applied would be great. Heartworm, which is transmitted to dogs by mosquitoes, is debilitating and fatal if it is left undiagnosed. An annual blood test should also be performed for early detection and treatment if necessary.

Constructive Conclusions for Healthy Dogs

As seen, the administration of a successful treatment in case of heart disease depends on many factors. However, the early detection of dilated cardiomyopathy and other heart diseases in dogs is by far the most important one of them. Following strict indications, you can help your dog live longer and have a more comfortable life if it happens to get sick.

Besides watching your dog’s health, you can do plenty of other things that will keep your dog happy and in top shape. For example, make sure your canine friend is exercising enough and it follows a balanced diet. An obese dog may have various difficulties when it comes to staying healthy. If you want to know how much exercise your dog needs, read our article on the subject. You being concerned for your dog’s health and it being under veterinary supervision can prevent the occurrence of heart diseases throughout its life.


Unfortunately, there are cases when dogs are simply born with a certain type of heart disease and you cannot do anything to prevent it. Those cases should not upset you because you can still do plenty for your dog to feel comfortable and live happily without putting too much pressure on it.

Usually, the cases when a dog’s heart gets bigger are not innate, but you never know what disease could affect your beloved animal. Regardless of what it really is, try to stay as informed as possible and avoid making mistakes. Spare your dog from noise, agitation, stressful situations, and other factors that might disturb its day-by-day routine.