Hypertrophic cardiomyopathy (HCM) is the most common feline heart condition, with around 15% of cats, and nearly 1 in 3 cats over 9 years of age, being affected¹. The disease is characterised by thickening of the left ventricular myocardium, resulting in impaired relaxation, diastolic dysfunction and, eventually, congestive heart failure or thromboembolic events.

Despite its prevalence and decades of research, feline HCM remains a challenging disease to diagnose and predicting how it will manifest in any individual cat can feel like educated guesswork at best.

The silent disease

Cats are, without doubt, masters of disguise. HCM often has a long subclinical phase, during which affected cats appear clinically well. For many, the first or only sign of disease may be a sudden onset of heart failure or aortic thromboembolism.

Even on clinical examination, HCM can be elusive. Some cats have a systolic murmur, gallop rhythm, or arrhythmia—but many do not. And to complicate matters further, not all murmurs in cats indicate structural heart disease.²

Diagnostic challenges

So how do we diagnose feline HCM with confidence?

Echocardiography remains the gold standard, but it’s far from perfect. Interobserver reliability of cardiac measurements remains a challenge, and both cost and specialist availability may limit how accessible echocardiography is for some owners.

Several “copy-cats” (such as hypertension, hyperthyroidism, and transient myocardial thickening) can mimic HCM on echo, and even minor technical deviations—like including moderator bands, or the endocardium in measurements, or obtaining slightly oblique imaging planes —can lead to overdiagnosis.

Then there’s the “cats will be cats” factor: tachycardia and hypertension, and movement artefacts caused by feline wriggliness and their reluctance to be examined, all affect reliability. For both feline and human participants, the process is rarely stress-free, and for affected cats, especially, is not without risk.

When we consider that 60–70% of cats with HCM will remain asymptomatic for life³, the benefits of investigation and frequency of follow-up must be carefully balanced against the cost, stress, and risks involved, and care taken not to over-diagnose.

Wouldn’t it be great if we had an easier test?

That’s exactly why there’s growing interest in biomarkers for HCM.

A biomarker capable of identifying disease before clinical signs or advanced structural change occur, could transform feline cardiology. A simple, accessible and cost-effective blood test to identify at-risk or affected cats would enhance screening programmes, refine case selection for referral, and support more confident diagnoses.

Commercially available markers such as NT-proBNP and cardiac troponin I (cTnI) are already in use and are valuable in distinguishing cardiac from non-cardiac causes of respiratory distress^4-8. However, since they only rise after cardiac stretch, pressure overload, or myocyte injury has occurred, they are best applied to those with moderate to severe clinical disease, and their ability to detect subclinical HCM, is limited.

Enter microRNAs?

MicroRNAs (miRNAs) are tiny, non-coding RNA molecules that regulate gene expression – acting like molecular “project managers”, switching cellular pathways on and off. Many of these pathways are central to cardiac hypertrophy, fibrosis, and remodelling.

Changes in microRNA expression are associated with disease. Since these changes are seen before tissue damage has even occurred, miRNAs have fantastic potential as markers of early or subclinical disease.

It’s no surprise, therefore, that miRNAs are receiving a lot of attention in the scientific community. In human cardiology, miRNAs have already shown great promise as diagnostic and prognostic biomarkers for cardiomyopathies, including HCM. And now, thanks to pioneering team of veterinarians and scientists at MI:RNA, the same is now true for cats.

Cutting edge science

MI:RNA have combined the power of cutting-edge molecular science with AI-driven analysis to reveal distinct miRNA expression patterns in cats with HCM compared to healthy controls.

This raises an exciting possibility: a simple blood test capable of identifying cats with HCM—and perhaps even detecting disease in its earliest, subclinical phase, before myocyte damage occurs.

So, while we won’t be putting down our stethoscopes or scanners any time soon, miRNA technology could soon add a powerful new tool to our diagnostic toolbox—offering molecular-level insight into what’s happening inside the feline heart.

If microRNAs can reveal what echocardiography and current biomarkers miss, they could transform how we detect, monitor, and manage feline heart disease. From the consultation room to the laboratory, these tiny molecules may well have a huge impact on feline health—and on how we care for our patients.

Excited to find out more?

Join us and the MI:RNA team at the London Vet Show to learn more about how this groundbreaking technology could change the future of feline cardiology. Stop by our stand (P45), meet the team behind the research, and discover how big a difference these tiny molecules might make.

References:

1. Payne JR, Brodbelt DC, Luis Fuentes V. Cardiomyopathy prevalence in 780 apparently healthy cats in rehoming centres (the CatScan study). J Vet Cardiol 2015; 17 Suppl 1: 5244-5257.
2. Paige CF, Abbott JA, Elvinger F, Pyle RL. Prevalence of cardiomyopathy in apparently healthy cats. J Am Vet Med Assoc. 2009 Jun 1;234(11):1398-403. doi: 10.2460/javma.234.11.1398. PMID: 19480619.
3. Fox PR, Keene BW, Lamb K,et al. International collaborative study to assess cardiovascular risk and evaluate long-term health in cats with preclinical hypertrophic cardiomyopathy and apparently healthy cats: The REVEAL Study. J Vet Intern Med. 2018 May;32(3):930-943. doi: 10.1111/jvim.15122. Epub 2018 Apr 16. Erratum in: J Vet Intern Med. 2018 Nov;32(6):2310. doi: 10.1111/jvim.15285. PMID: 29660848; PMCID: PMC5980443.
4. Ward JL, Lisciandro GR, Ware WA, et al. Evaluation of point-of-care thoracic ultrasound and NT-proBNP for the diagnosis of congestive heart failure in cats with respiratory distress. J Vet Intern Med 2018; 32: 1530-1540
5. Wurtinger G, Henrich E, Hildebrandt D, et al. Assessment of a bedside test for N-terminal pro B-type natriuretic peptide (NT-proBNP) to differentiate cardiac from non-cardiac causes of pleural effusion in cats. BMC Vet Res 2017; 13:394.
6. Connolly DJ, Soares Magalhaes RJ, Fuentes VL, et al. Assessment of the diagnostic accuracy of circulating natriuretic peptide concentrations to distinguish between cats with cardiac non-cardiac causes of respiratory distress. J Vet Cardiol 2009; 11: S41-S50.
7. Wells SM, Shofer FS, Walters PC, et al. Evaluation of blood cardiac troponin I concentrations obtained with cage-side analyzer to differentiate cats with cardiac and noncardiac causes of dyspnea. J AM Vet Med Assoc 2014; 244: 425-430.
8. Connolly DJ, Brodbelt DC, Copeland H, Collins S, Fuentes VL. Assessment of the diagnostic accuracy of cardiac troponin I concentration to distinguish between cats with cardiac non-cardiac causes of respiratory distress. J Vet Cardiol 2009; 11: 71-78.