By Dr.Sophia Martinez
Understanding Heart Murmurs in Cats: Pathophysiology, Prognosis & the Potential Role of Coenzyme Q10 (CoQ10)
When a veterinarian listens to a cat’s heart and hears an unexpected “whoosh” or “swoosh” beyond the usual “lub-dub,” that sound may represent a heart murmur. But a murmur is not a diagnosis in itself—it is a clinical clue that something may be altering blood flow within the heart or vessels. In this article, we explore the underlying mechanisms of feline heart murmurs, how veterinarians investigate them, prognostic implications, and whether Coenzyme Q10 (CoQ10) supplementation might have a theoretical or adjunctive role in supporting feline cardiac health.
Disclaimer: This article is for informational / educational purposes only. It does not replace veterinary diagnosis or treatment. Always consult your cat’s veterinarian before giving any supplement.
What is a Heart Murmur in Cats?
A heart murmur is an extra sound heard during the heartbeat cycle, generated by turbulent or high-velocity blood flow across cardiac structures (valves, septa, or vessels). 👉 Cornell Feline Health Center Murmurs are classified by timing (systolic, diastolic, continuous) and by intensity (often graded I to VI). 👉 MetLife Pet Insurance
Important caveat: not every murmur indicates a significant disease. Some murmurs are “innocent” or “physiologic” — transient, benign, or secondary to non-cardiac causes (e.g. anemia, hyperdynamic circulation). MetLife Pet Insurance
Causes of Murmurs & Clinical Implications
Murmurs in cats may result from a spectrum of structural or functional perturbations:
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Congenital defects such as ventricular septal defects (VSDs), atrial septal defects, or valvular malformations may cause abnormal shunting or turbulent flow. PetMD
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Acquired heart disease (e.g. hypertrophic cardiomyopathy, valvular degeneration, cardiomyopathies) can alter chamber geometry, pressure gradients, or cause regurgitant flow. PetMD
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Functional / secondary murmur sources: anemia, hyperthyroidism, systemic illness, high cardiac output states, or stress may produce transient murmurs even in structurally normal hearts. MetLife Pet Insurance
The grade of the murmur (I–VI) is a rough indicator of audibility, but not always correlated tightly to the severity of underlying pathology. Some severe lesions may have soft murmurs, while louder murmurs may stem from milder causes. legacyamc.com
Diagnostic Workflow & Prognosis
Once a murmur is detected, veterinarians typically proceed with follow-up investigations:
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Baseline workup: physical exam, complete blood count, chemistry panel, thyroid function, blood pressure.
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Thoracic radiographs (X-rays) to assess heart size, pulmonary vasculature, lung fields.
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Electrocardiogram (ECG) to detect arrhythmias.
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Echocardiography (cardiac ultrasound with Doppler) is the gold standard for visualizing heart structure, chamber dimensions, valve motion, pressure gradients, and evaluating whether the murmur corresponds to a structural abnormality.
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Optional: cardiac biomarkers (e.g. NT-proBNP), further advanced imaging as needed.
Prognosis depends heavily on the underlying cause. Some cats harbor benign murmurs that remain stable for life; others may progress to structural heart disease or heart failure. PetMD In cats with diagnosed heart disease, signs may include lethargy, reduced appetite, changes in breathing pattern, or sudden events like arterial thromboembolism. In cats that progress to congestive heart failure, survival may range from months to a few years depending on severity and response to therapy. PetMD
Coenzyme Q10 (CoQ10): Biology & Evidence
Coenzyme Q10 (ubiquinone / ubiquinol, abbreviated CoQ10) is a vital component of the mitochondrial electron transport chain, essential for ATP generation in cells. It also acts as an antioxidant, helping scavenge free radicals and protect membranes from oxidative damage.
In human cardiovascular medicine, a growing body of literature supports CoQ10 supplementation in conditions such as heart failure, hypertension, and cardiomyopathies to improve functional outcomes, reduce oxidative stress, and enhance endothelial function.
In veterinary medicine, data are far more limited:
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In cats and dogs, CoQ10 is used as a supplemental therapy for heart and neurological conditions, capitalizing on its antioxidant and mitochondrial support roles. Vca
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CoQ10 supplementation in pets is considered generally very safe, and absorption can be improved when given with food (especially fatty meals). Coenzyme Q10 use in pets
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However, no definitive controlled clinical trials currently confirm that CoQ10 significantly alters prognosis or reverses structural heart disease in cats. TUFT
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Some studies in dogs with congestive heart disease (e.g. mitral valve disease) have shown that CoQ10 may reduce oxidative stress and inflammatory markers (neutrophil/lymphocyte shifts) as a supportive adjunct. National Library of Medicine
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A review of dietary supplements in veterinary cardiology notes that while human data are promising, translation to dogs and cats remains speculative. vetspecialists
Potential Role & Limitations of CoQ10 in Cats with Murmurs
Theoretical benefits might include:
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Supporting mitochondrial energy production in myocardial cells, thus helping stressed cardiomyocytes cope with increased workload.
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Reducing oxidative stress in cardiac tissues, which may slow progression of subclinical damage.
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Acting as a complementary (not replacement) support alongside standard veterinary therapies.
Important limitations & cautions:
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Lack of robust clinical outcome studies in cats means benefits are speculative.
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Bioavailability, formulation quality, dose standardization are nontrivial issues in pet supplements.
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Supplementation should not replace vet-recommended medications, imaging follow-ups, or disease-targeted therapies.
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Always monitor for any adverse interactions or side effects and maintain transparent communication with the veterinarian.
Practical Recommendations (Under Veterinary Oversight)
If considering CoQ10 supplementation in a cat with a heart murmur (particularly one without overt heart failure), one might:
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Use a well-formulated, pet-specific CoQ10 soft chew or chewable formulation.
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Administer a fatty meal to enhance absorption.
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Start with a conservative dose, monitor clinical signs (activity, appetite, breathing, weight) and periodically reassess with imaging or biomarkers if available.
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Inform the veterinarian of all supplements being used to avoid interactions.
A heart murmur in cats is an important clinical finding—but it’s not a diagnosis on its own. The cause behind it, whether structural, functional, or temporary, determines how serious it is and what treatment is needed. While CoQ10 isn’t a medical cure for feline heart disease, it has shown promising potential as a mitochondrial and antioxidant support that helps maintain healthy cellular energy and cardiovascular function.
That’s where Pawbio’s CoQ10 Soft Chews for Cats come in. Formulated with bioavailable Coenzyme Q10 and designed for daily wellness, our soft chews offer gentle, vet-approved support for heart health and vitality. When used under veterinary guidance, Pawbio’s CoQ10 may serve as a complementary aid to help your cat stay energetic, balanced, and thriving—one delicious chew at a time.
