Dilated Cardiomyopathy in Dogs
Causes
Symptoms
Risk
Diagnosis
Vet treatment
Home treatment
Prevention
what to expect
When to worry
Dilated Cardiomyopathy in Dogs
Dilated Cardiomyopathy (DCM) is the second most common form of heart disease in dogs, and the most common in large breeds. Some breeds, like the Dobermann and Great Dane, are at much higher risk. There are different types of DCM, but in most cases this is a very serious condition. Speak to a vet straight away if your dog seems overly tired, is breathing abnormally or faints.
DCM causes a dog’s heart muscle to become thinner and weaker over time. This causes poor blood flow and congestion. The heart needs to work harder to move the blood, creating a vicious cycle that leads to congestive heart failure. This is when the symptoms suddenly appear. In DCM, the changes to the heart muscle may additionally cause problems with the heart rhythm (arrhythmias).
When DCM is detected early, treatment may slow down the progression of the disease and reduce complications. Even if the disease is already established, medication can greatly improve the quality of life and manage the symptoms for some time.
What causes Dilated Cardiomyopathy in Dogs?
The exact mechanisms of DCM haven’t been fully understood. In most cases, a combination of factors results in the disease. These include genetics, nutrition, infections and drugs/medications.
Genetics are thought to be a big factor in the development of DCM, especially in high-risk breeds like Dobermann, Irish Wolfhound and Great Dane. So far, no specific gene mutation has been found, and it seems that multiple genes contribute to the problem at the same time.
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The heart muscle is very special and has specific nutrient requirements. Nutrition may play a key role in a minority of cases of DCM, especially in dogs that don’t belong to a high-risk breed. Possible nutritional issues include:
Diets containing large proportions of peas, lentils, beans or chickpeas. This is still being debated and investigated, but some dogs with DCM seem to improve when changed from foods like this to a more traditional dog food.
Low levels of the amino acid taurine and its predecessors (methionine and cysteine). This may be due to unbalanced diets or because some dogs have problems using these amino acids. Breeds at higher risk of developing taurine deficiency include Golden Retrievers, American and English Cocker Spaniels, and Newfoundlands.
Boxers and Bulldogs may develop a special type of arrhythmia-associated DCM called Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC). In Boxers with DCM, some studies have shown low levels of L-carnitine in the heart muscle.
Puppies exposed to the virus that causes Parvovirosis at a very young age (before 4 weeks old) may develop a severe and often fatal form of DCM. There is also a parasite in some parts of North and Central America that can affect the heart muscle (Trypanosoma, causing Chagas disease).
Some drugs can also cause heart disease as a side effect. In dogs, the most relevant example is Doxorubicin. This is a medication used for chemotherapy against some types of cancer. It rarely causes heart problems when used according to protocol, but in rare cases, it may cause a form of DCM.
Symptoms of Dilated Cardiomyopathy in Dogs
Early (and sometimes even intermediate) stages of DCM may not cause any obvious symptoms. When symptoms appear, we may see:
Low energy
Struggling to exercise
Weakness
Sudden death
Dogs at higher risk of developing Dilated Cardiomyopathy
DCM is much more common in large dogs. Mid-size dogs can sometimes be affected, especially Spaniels. DCM is very rare in small dogs.
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Breeds more commonly affected include:
Dobermann pinscher (very common in this breed, may affect more than half of Dobermanns)
Boxer
Great Dane
German Shepherd
Irish Wolfhound
Newfoundland
Saint Bernard
Labrador and Golden Retrievers
American and English Cocker Spaniels
Dogs eating diets containing large proportions of peas, lentils, beans or chickpeas may be at higher risk of DCM. However, studies haven’t been clear regarding this possibility. This matter is still being investigated. For now, the only thing that seems clear is that some dogs that have been eating such diets and are diagnosed with DCM may benefit from changing to a more traditional complete diet for dogs.
Diagnosis of Dilated Cardiomyopathy in Dogs
Dilated cardiomyopathy is difficult to detect in the early stages, even during a physical examination. This is because the disease may not initially cause any obvious symptoms.
Given the high levels of disease in some breeds, and that disease may cause damage for a long time before the symptoms develop, screening tests are advisable for some dogs (particularly Dobermanns). Your vet can advise on the best approach for your dog.
Sometimes the first symptom of DCM is detected during a routine physical examination, such as a heart murmur or an abnormal heart rhythm. The vet will likely recommend further tests to check the cause and severity of the problem.
Echocardiography (a heart scan) is the key test to confirm DCM in dogs. It allows assessment of the heart muscle, blood flow and heart valves.
Electrocardiography (ECG) is a test to assess the heart rhythm. This test is very important in breeds that have a tendency to develop arrhythmia, such as Boxers and Dobermanns. The arrhythmia may be just as much (or more) of an issue than heart failure. Sometimes the arrhythmia develops before any other changes, and the ECG can also be used to detect early disease. In such cases, the ECG may need to be done over 24 hours or more (Holter or portable ECG).
Chest x-rays may be recommended, especially if the vet is worried about fluid build-up in the lungs.
Blood pressure readings can be useful to assess the quality of blood flow throughout the body.
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Blood tests may be recommended in cases of suspected DCM for two reasons:
NT-proBNP and Troponin blood tests can be used to detect and monitor heart disease. These parameters go up when the heart muscle is struggling and can be used to confirm that the primary issue is heart disease.
Blood tests may be useful to rule out other diseases, especially if an arrhythmia is the only symptom present.
As our knowledge of the genetic causes of DCM improves, genetic tests may become available to detect dogs at risk of developing the disease.
Veterinary Treatment of Dilated Cardiomyopathy in Dogs
There is no cure for DCM, but treatments may improve quality of life and delay the development of disease or serious complications.
A study performed in Dobermanns has shown that Pimobendan may delay disease progression in early stages, thus delaying the symptoms and extending quality of life. This has not been confirmed in other breeds, but it is thought to also work for them.
In all breeds, Pimobendan is recommended when symptoms start. This medication improves heart strength and blood flow, and is one of the most effective supportive treatments for heart disease in dogs.
Dogs that have developed sudden complications of DCM, such as trouble breathing, will need to be hospitalised to receive oxygen treatment and emergency care.
Diuretics, like Furosemide, are also an important part of the treatment. Especially if there are signs of congestion, like coughing or tummy swelling. As the disease worsens, stronger diuretics (Torasemide) or combinations of diuretics (spironolactone, hydrochlorothiazide) may be prescribed.
Angiotensin converting enzyme (ACE) inhibitors are another type of medication commonly used for heart failure in dogs. Examples include Benazepril and Enalapril. They improve blood flow and counteract some of the negative effects of the vicious cycle the heart is in.
Anti-arrhythmia medications are a crucial part of the treatment when arrhythmias are present. Arrhythmias are likely behind most cases of sudden death in dogs with DCM, and can also worsen the disease in other ways. The type of arrhythmias that affect dogs with DCM are treated with medication (a pacemaker won’t help). There are different types of arrhythmia, and each type has its own class of medication for treatment. Examples of anti-arrhythmics include diltiazem, digoxin, sotalol and mexiletine.
Home Treatment of Dilated Cardiomyopathy in Dogs
In high-risk breeds like the Dobermann and Boxer, it may be advisable to discuss a screening and monitoring plan with your vet. If the disease is detected early on (well before symptoms start), it may be possible to prevent some life-threatening complications. Medication may also be more effective if started early, when the heart muscle starts to change.
For dogs at lower risk, vet checks 1-2 times per year may be sufficient for monitoring.
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It may also be useful to monitor the resting breathing rate.
Count how many times your dog’s chest moves in a minute, while they’re relaxing. The normal rate is 15-30 breaths per minute. If you count more than 30 breaths multiple times, speak to a vet for further advice.
If heart disease has been diagnosed, avoid stressful situations when possible. This can be things like sudden changes to their routines or forcing them into a situation they find unpleasant (vet visits can’t be completely avoided, unfortunately).
In cases where nutrition is thought to be a factor in the development of disease, a change in diet may reduce the progression of disease, or even reverse some of the changes if the problem was caught early.
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Dogs that are eating a good quality, age-appropriate and complete diet that doesn’t contain high levels of pulses (peas, lentils, beans, chickpeas), will probably not benefit from a diet change in the early stages of heart disease.
This may change when the disease becomes more severe, especially if they are having a lot of issues with fluid build-up. Your vet can provide further advice for your dog’s specific situation.
Prevention of Dilated Cardiomyopathy in Dogs
In most cases there isn’t much that can be done to prevent the development of DCM.
Feeding a high-quality, complete diet, maintaining a healthy body condition (weight) and being active are always good ways to improve health.
Pre-emptive screening tests should be considered in the Dobermann and other high-risk breeds. Early detection may significantly improve the outcome.
Regular vet checks also help with early detection.
What to expect for my dog with Dilated Cardiomyopathy
DCM is a serious and complex disease. Every dog is different, and how well they respond to treatment will also affect how they progress.
In cases where nutrition is part of the problem, correcting this may reduce or even reverse the disease, but unfortunately, this doesn’t happen often.
As previously mentioned, treatment is usually more effective if the disease is detected early, especially before showing any obvious symptoms. The form of disease seen in Cocker Spaniels tends to progress more slowly as well. In some dogs, the disease can be managed for a year or two.
When symptoms develop, these are often very serious, and the disease usually progresses quickly. Most dogs survive less than 6-12 months. This is especially the case for Dobermanns.
Severe arrhythmias that don’t respond to treatment usually lead to fatal complications quite quickly.
When to worry about Dilated Cardiomyopathy in Dogs
Seek help from an emergency vet if your dog:
Is struggling to breathe or gasping for air
Has blue or grey gums
Is very tired and you are struggling to wake them up
Is struggling to stand up
Call a vet as soon as possible if your dog:
Faints
Has a resting respiratory rate consistently above 30 breaths per minute
Is losing weight or has less appetite
Is spending a lot of time sleeping
Joii can help if:
You need help looking after your dog with heart disease
You need guidance on how to take your dog’s resting respiratory rate
You need advice on feeding your dog with heart disease
You need tips on how to give medication to your dog
