Dilated Cardiomyopathy
- veterinaryvoicesuk
- 2 days ago
- 7 min read
ABSTRACT:
Dilated cardiomyopathy (DCM) is the most common cardiac disease in large breed dogs and is inherited in Doberman Pinschers with a high prevalence. This article looks at DCM clinical signs, diagnosis, treatment and specifically looks into monitoring and screening, particularly for the Doberman Pinscher breed.
Introduction
Dilated cardiomyopathy (DCM) is the most common cardiac disease in large breed dogs and is inherited in Doberman Pinschers with a high prevalence (58%), in a European study, 1.1% of the dog population seen at veterinary hospitals were diagnosed with DCM. Historically, DCM has been considered to be primarily an inherited disease, with higher prevalence in specific dog breeds, however there are occasionally other causes of DCM including specific nutrient deficiencies and concurrent diseases, such as endocrine, myocarditis, and chronic tachycardia.
Breeds Predisposed to Dilated Cardiomyopathy (DCM)
DCM has traditionally been recognised as a genetic, inherited heart disease, with some breeds at significantly higher risk than others.
Breeds with an increased incidence include:
Doberman Pinschers
Irish Wolfhounds
Great Danes
Boxers
American & English Cocker Spaniels
Bulldogs
Golden Retrievers
Saint Bernards
Airedale Terriers
Newfoundlands
Scottish Deerhounds
Key Points
30–50% of DCM cases are thought to have a hereditary basis.
Male dogs are generally affected more frequently than females.
Doberman Pinschers are among the highest-risk breeds, with studies reporting DCM in approximately 50% of males and 33% of females.
Irish Wolfhounds have an estimated breed incidence of around 25%.
DCM most commonly affects middle-aged to older dogs, although rare juvenile forms have been reported, particularly in Portuguese Water Dogs.
What causes Dilated Cardiomyopathy (DCM)?
Dilated cardiomyopathy is not a single disease with a single cause. Around 30–50% of cases are thought to be inherited, meaning they are caused by changes (mutations) in genes that are passed from parents to their offspring. Scientists have now identified many different genes that can increase a dog's risk of developing DCM, particularly in predisposed breeds such as Doberman Pinschers.
These genes are responsible for producing proteins that allow the heart muscle to contract, maintain its structure, generate energy, and coordinate its electrical activity. When these proteins do not function correctly, the heart gradually becomes enlarged, weaker, and less able to pump blood effectively.
Interestingly, one paper discusses how different dog breeds tend to develop distinct forms of DCM, making them valuable naturally occurring models for studying the disease. Because many breeds have relatively limited genetic variation, researchers can more easily identify the genes involved and investigate how they affect the heart. This research not only helps improve breeding decisions, diagnosis, and treatment in dogs, but may also provide valuable insights into human heart disease. Likewise, advances made in human cardiology continue to improve the care available for dogs with DCM.
Not all cases are genetic, however. DCM can also develop secondary to other conditions, including nutritional deficiencies, certain heart rhythm disorders, inflammation of the heart muscle (myocarditis), endocrine diseases, and, in some cases, diet-associated factors.
Although researchers have identified many genes involved in DCM, they have also found that different genetic mutations often lead to the same final result: progressive weakening and enlargement of the heart muscle. This has shifted research towards developing treatments that target the common disease processes, rather than focusing on individual genes alone. Scientists are also exploring gene therapies and new medications that may help slow or prevent disease progression in the future.
Clinical manifestation and signs
The heart is incredibly good at compensating, and due to these incredible compensatory mechanisms, DCM can initially manifest in a subclinical phase, otherwise known as the occult phase, when we don't see any changes to our pets health or behaviour at all! Occasionally the patient may experience decreased systolic function and arrhythmias in the occult phase.
As the disease progresses, cardiac contractile function (its ability to contract effectively) diminishes, resulting in decreased cardiac output. Furthermore, continued myocardial remodelling may result in dangerous arrhythmias. When the heart is no longer able to compensate for the disease, for example by trying to pump harder, the tipping point in the disease process is when clinical signs, such as exercise intolerance, congestive heart failure (CHF), syncopal episodes, and sudden cardiac death (SCD), occur. Often, SCD may be the first manifestation of this disease and can occur in up to 40% of Dobermans.
Diagnosis
There are a number of ways we may check for DCM in dogs.
Thoracic radiographs (X-Rays): can reveal generalised enlargement of the cardiac silhouette or more specifically enlargement in the area of the left atrium and left ventricle, this gives the heart a big, round globoid appearance.
Ultrasound: Echocardiography is necessary to definitively differentiate DCM from other cardiovascular diseases
Electrocardiogram (ECG) evaluation can reveal supraventricular and ventricular arrhythmias in addition to other abnormalities, It is important to note that a normal ECG does not rule out the presence of DCM, as most arrhythmias are intermittent and have high day-to-day variability which is why holters may be needed in more involved cases.
Holter monitoring: Holter monitoring is the gold standard screening tool to detect arrhythmias in dogs, allowing for detection of over a 24-h window. The presence of greater than 50 ventricular premature complexes of a Holter monitor is indicative of DCM in Doberman Pinschers
Cardiac Biomarkers: Diagnostic tools are commonly coupled with assessing cardiac biomarkers, such as NT-proBNP and cardiac troponin, for a more comprehensive picture of the DCM stage being evaluated
Treatment
Early screening and detection of DCM may positively impact the longevity of dogs. Once diagnosed with DCM, the administration of pimobendan, a positive inodilator, may significantly delay the onset of congestive heart failure in Doberman Pinschers and other breeds. Therefore, pimobendan has become a standard therapy in dogs with decreased systolic function and left ventricle dilation.
Recommendations for Dobermans
As Dobermans are particularly prone to this, and up to 40% may only manifest as sudden cardiac death, screening may help to monitor Dobermans (and other 'at risk' breeds) and ensure that any animals wanted for breeding purposes aren't bred if they are showing any signs of DCM, which they could pass onto their young.
The European Society for Veterinary Cardiology stated that screening for occult DCM in Dobermans should start at three years of age and use both Holter monitoring and echocardiography.
They state that yearly screening over the life of the dog is recommended, as a one-time screening is not sufficient to rule out future development of DCM - it may develop later on in life.
What are we looking for?
The preferred echocardiographic method is the measurement of the left ventricular volume by Simpson's method of discs (SMOD). Less than 50 single ventricular premature complexes (VPCs) in 24 h are considered to be normal in Dobermans, although detection of any number of VPCs is cause for concern. Greater than 300 VPCs in 24 h or two subsequent recordings within a year showing between 50 and 300 VPCs in 24 h is considered diagnostic of occult DCM in Dobermans regardless of the concurrent echocardiographic findings.
The guidelines also provide recommendations concerning ancillary tests, that are not included in the standard screening protocol, but which may have some utility when recommended tests are not available or financially untenable on an annual basis. These tests include assay of cardiac biomarkers (Troponin I and N-Terminal pro-B-type Natriuretic Peptide) as well as a 5-min resting electrocardiogram (ECG).
Non-hereditary (Diet-Associated) Dilated Cardiomyopathy
Although dilated cardiomyopathy has traditionally been considered an inherited disease affecting predisposed breeds, research over the past decade has identified a form of non-hereditary (diet-associated) DCM in dogs without a known genetic predisposition.
Interest in this condition grew in 2018 when the US Food and Drug Administration (FDA) began investigating reports of DCM in dogs eating certain "non-traditional" diets, many of which were marketed as grain-free or contained high levels of pulses and legumes, such as peas and lentils. Importantly, the FDA has not concluded that grain-free diets alone cause DCM. Rather, current evidence suggests that diet-associated DCM is likely a complex condition involving interactions between diet formulation, nutrient bioavailability, ingredient composition, genetics, and underlying health conditions. Research into the exact mechanism remains ongoing.
Since the FDA's investigation began, a growing body of scientific literature has strengthened the evidence that diet can play a role in some cases of DCM. Studies have identified subtle changes in heart structure and rhythm in apparently healthy dogs consuming high-pulse diets, while several clinical studies and case reports have demonstrated that some affected dogs experience significant improvement in cardiac function following a change to a more traditional diet alongside appropriate veterinary treatment. Unlike inherited DCM, which is typically progressive, this suggests that diet-associated DCM may be partially reversible if recognised and treated early.
Recent research has also proposed several potential mechanisms, including alterations in nutrient absorption, changes to the gut microbiome, phospholipid metabolism, and the effects of high concentrations of pulse ingredients. However, no single ingredient or nutrient has yet been identified as the sole cause, and further research is needed before definitive conclusions can be drawn.
For pet owners, the key message is not that grains are inherently beneficial or that grain-free diets are universally harmful. Rather, current evidence supports feeding a nutritionally complete and balanced diet formulated by appropriately qualified veterinary nutrition experts and, where possible, supported by feeding trials. Owners considering grain-free or boutique diets should discuss their choice with their veterinary surgeon, particularly if their dog belongs to a breed already predisposed to DCM or has existing cardiac disease.
As our understanding of diet-associated DCM continues to evolve, veterinarians, researchers, and regulatory agencies continue to recommend a cautious, evidence-based approach. The FDA has emphasised that investigations into non-hereditary DCM are ongoing and continues to encourage collaboration between veterinary cardiologists, nutritionists, academia, and the pet food industry to better understand the condition.
Citations:
Robyn Lowe
BSc Hons, Dip AVN (Surgery, Medicine, Anaesthesia) DipHE CVN, RVN
Clinical Information Relevant as of 2026 - progression in new treatment in veterinary medicine is fast paced so if you note something where new information is present please let us know and we can update before our normal review dates
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