Heart failure and heart disease in dogs

What is heart disease in the dog?

Heart disease in dogs has two main forms. Myxomatous mitral valve degeneration (MMVD) is by far the most common and affects particularly small breeds such as the Cavalier King Charles Spaniel and the Dachshund. In large breeds, including the Dobermann and Irish Wolfhound, dilated cardiomyopathy (DCM) occurs more frequently. Both conditions can lead to congestive heart failure, where the heart no longer pumps enough blood around the body.

Conventional treatment is essential. Agents such as pimobendan, ACE inhibitors and furosemide are the proven, life-extending pillars of heart failure treatment in dogs. No supplement replaces this medication. Additional options can at most play a supportive role, and always in consultation with a veterinary surgeon or cardiologist.

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Additional options: what does the evidence say?

Taurine — evidence present in specific cases

A prospective observational study in golden retrievers with DCM and low taurine levels showed that dietary adjustment combined with taurine supplementation led to demonstrable improvement of heart function and normalisation of taurine levels [3]. The association proved strong in dogs that received grain-free or legume-rich feed.

Taurine measurement is useful in golden retrievers with DCM, certainly with this dietary pattern. Whether this effect also applies to other breeds or other causes of DCM has not been demonstrated.

Omega-3 fatty acids (fish oil) — one RCT with positive result

In a randomised controlled study in Boxer dogs with arrhythmogenic right ventricular cardiomyopathy (ARVC), omega-3 fatty acids from fish oil significantly reduced the number of ventricular extrasystoles [2]. Linseed oil showed no effect in that same study — the source of the fatty acids thus appears relevant.

This is the strongest evidence base in this domain, but the research concerns one breed with a specific cardiac arrhythmia. Translation to other breeds or heart diseases requires caution.

CoQ10 — promising signal, no clinical evidence

Heart muscle tissue of Cavalier King Charles Spaniels with congestive heart failure contains significantly lower CoQ10 levels than in healthy dogs [1]. This is a relevant biological signal, but whether oral CoQ10 supplementation restores those levels AND has a clinical effect has not been investigated in dogs in controlled studies. It is too early to recommend CoQ10 based on the current evidence.

Salt restriction — nuanced

Salt restriction is common in advanced heart failure, but extreme sodium restriction in early stages is not proven beneficial and can activate the renin-angiotensin-aldosterone system, which is detrimental. Dietary advice depends strongly on the stage of the disease and must be assessed individually by a veterinary surgeon.

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Additional is not the same as replacing

Always discuss with a (veterinary) cardiologist which supplements are useful for the specific condition, the breed and the stage of heart disease of your dog.