Why Home Monitoring is the Heart of Cardiology

How do you really monitor a patient’s heart disease once they leave the consult room? And how do we compensate for the fact that pain, stress or anxiety can make many baseline markers (such as blood pressure, heart rate and respiratory rate) look so different in the clinic?

This is something many of us struggle with. We need to move beyond the clinical examination and identify markers that better reflect a patient’s normal state at home. It is in the home environment that some of the most valuable clinical data originates. Often, the most useful measures are the baseline or resting values.

When pets develop heart failure, the earliest warning signs of relapse or deterioration often appear at home days before overt clinical distress becomes obvious. Patients are remarkably stoic, and because they are naturally efficient athletes, subtle reductions in exercise tolerance can go unrecognised until disease is advanced. Currently, we rely on owners performing manual sleeping respiratory rate (SRR) counts. Monitoring SRR is arguably the most reliable home-monitoring tool for detecting congestive heart failure (CHF). Published data shows that breathing rates recorded at home during deep sleep are nearly as effective as thoracic radiography and echocardiography for detecting CHF.

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There is now growing evidence that monitoring heart rate at home may also prove similarly useful, although presents more challenges to achieve reliably without training or disturbing the patient.

But is it as easy to do in practice?

This gold standard only works if the patient is truly relaxed, ideally in a deep, non-dreaming sleep, in a cool environment and free from stressors. We have all tried to creep up on a sleeping inpatient to record an accurate respiratory rate – and often with little success! Remarkably acute hearing and instinctive reactions mean that many animals shift position or wake up the moment they sense they are being observed. If owners are counting while the pet is simply resting rather than genuinely asleep, the data becomes less reliable – particularly if the patient becomes aware of the process and stressed by it.

Seasonal and diurnal variation can also complicate interpretation. Evidence shows that SRR is naturally higher in the summer than in winter, and higher during the daytime than overnight. Thankfully, species, size and breed do not appear to have a major influence. Age, however, certainly does – it is entirely normal for puppies and kittens to breathe considerably faster than adults. (Reference: AI-COLLAR study, Chetboul et al. 2025) Chetboul, V., Humbert, E., Dougoud, L., & Lorre, G. (2025). Resting heArt and respIratory rates in dogs in their natural environment: new insights from a long-term, international, prospective study in a COhort of 703 dogs using a biometric device for LongitudinaL non-invasive cARdiorespiratory monitoring (the AI-COLLAR study). Frontiers in veterinary science, 12, 1667355.  

It is also important to remember that diseases affecting the lungs or pleural space — not just cardiac disease – can also increase SRR. If you’re not sure and want to discuss a case with us, check out our case reviews.

Finally, humans are generally poor at recognising slow, gradual trends. If a patient becomes slightly less active over several weeks, it often goes unnoticed because normal day-to-day variation masks the drift. In veterinary cardiology, however, these subtle changes are frequently the earliest indication that a patient may be approaching a tipping point.

As it turns out, some of the most valuable cardiology data comes from a sleeping pet, a quiet room…and an owner trying not to breathe too loudly.

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