The myths and truths of owner observations
20th October 2025
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Owner observations that can make all the difference in spotting cardiac disease.
Owners often ask us what signs to look out for that might indicate heart disease. While breathlessness or collapse are the obvious clues, owners often have more information than they realise. Dogs and cats can present with very different (often subtle) signs.
When trying to decide if symptoms are cardiac, you may end up with more evidence from information initially perceived to be insignificant. Here are some of the myths we hear most often, and the truths behind them which might make you think twice when you’re taking a patient history. If there are complicating factors and you aren’t sure, our Cardiology team at HeartVets can help.
“He’s slowing down, but he is getting on a bit now so that’s expected, I suppose.”
Reduced exercise tolerance is often blamed on age or arthritis, but many older dogs maintain good cardiovascular fitness if they’re still exercising regularly. Unlike arthritic dogs (who often improve once they get moving), cardiac patients may tire quickly, stop on walks, or struggle to keep pace. Conditions such as degenerative mitral valve disease (DMVD), dilated cardiomyopathy (DCM), or even intermittent arrhythmias can all reduce stamina without causing overt collapse.
“It’s just the odd cough in the evening, but he never brings anything up, so I don’t think it’s anything to worry about.”
Cough timing and context are key. While airway disease often triggers coughing with excitement or exercise, an evening or nocturnal cough is more suspicious of cardiac disease. An enlarged left atrium compressing the left mainstem bronchus and recumbent positions during rest can both provoke a cough after prolonged periods of lying down.
“She’s coughing a lot, it’s like she’s got something stuck in her throat.”
A cardiac cough is typically harsh, dry, or hacking, often with a “terminal retch.” Small breeds with DMVD show this more commonly, whereas larger breeds with DCM may present with a softer, subtler cough.
“They’re panting more at home, but I put this down to the hot weather / the heating being on.”
It could be the temperature – but increased panting, especially if resting or sleeping respiratory rates are elevated, may indicate early pulmonary oedema. Many cardiac patients struggle in warmer months due to reduced cardiovascular adaptability. Owners often dismiss these signs as environmental, so it’s worth probing further if you hear this in a history.
“He’s lost a bit of weight, but he’s eating well – we probably just need to feed him a bit more.”
Cardiac cachexia can be subtle initially, particularly in patients who started out overweight or well-conditioned. Over time, loss of muscle mass becomes more obvious, with prominence of the spine and hips. Owners living with their pet day to day often fail to spot these gradual changes. In cats, thyroid assessment is key, but don’t forget to consider the heart even if hyperthyroidism is discovered.
“She’s sleeping more, but that happens with age, doesn’t it?”
It might – but lethargy and reduced engagement can also signal underlying structural disease or bradyarrhythmias, alongside other systemic or orthopaedic conditions.
“His belly seems bigger – I think he’s getting fat.”
Abdominal distension should always raise concern for cardiac disease. Venous congestion from left-sided congestive heart failure (CHF) can cause hepatomegaly, and right-sided CHF can lead to ascites. Right-sided failure can be due to congenital defects (e.g. tricuspid dysplasia, pulmonic stenosis) or secondary to pulmonary hypertension or tachycardia-induced myocardial failure.
“She still plays a lot – sometimes she pants a bit while playing, but then she goes straight back to it, so I think her exercise tolerance is fine.”
Unlike dogs, panting during exertion is rarely normal in cats. It can be an important sign of dynamic left ventricular outflow tract obstruction associated with hypertrophic cardiomyopathy (HCM), which worsens at higher heart rates. We know from human studies that this causes angina (chest pain) during exercise or exertion, and this is likely to be happening in our feline patients. Cats can also experience arrhythmias or myocardial hypoxia during exertion which may cause acute, transient respiratory signs. Feline patients may also self-limit after a negative experience of chest pain or breathlessness, becoming less playful over time. Asking about any past history of exertional panting, even if transient, can be revealing.
“There’s no collapse, but his back legs go a bit weak from time to time – I think it’s probably arthritis.”
It could be arthritis, but ataxia or transient limb weakness is also common in cats with arrhythmias. Myocardial diseases like hypertrophic cardiomyopathy (HCM) or arrhythmogenic right ventricular cardiomyopathy (ARVC) can cause haemodynamically significant arrhythmias without a full collapse episode.
“We don’t see a lot of her – she mostly stays upstairs and sleeps all day now. I guess that’s just age.”
Cats are experts at masking illness. Withdrawal, lethargy, and increased sleep may reflect an attempt to conserve energy in the face of significant underlying cardiac disease. Owners often miss this sign until other symptoms become more obvious.
Asking more targeted questions or listening closer to conversational responses from owners may well give you more information than you first thought. It also might be useful to use these ‘myths’ as prompts for owner education, to empower them to notice the more subtle signs of cardiac disease in their pet. More owner information can be found on our website.
Owner observations that can make all the difference in spotting cardiac disease.
In this article, we share the subtle findings that might change your approach to cardiac patients.