Heart Disease in Cats (HCM): Signs You Should Not Ignore

The hard part for owners is that HCM is often silent. A cat can carry it for years with no cough, no obvious slowdown, nothing you would notice at home, and then show signs suddenly once the disease is advanced. That is very different from the picture in dogs, and it is exactly why knowing the quiet warning signs matters so much.

Worried about your cat's breathing or energy? You can check the symptoms free in the Omelo app in about 30 seconds and get a plain read on whether they point to a vet visit and how urgently.

• Fast breathing at rest. A resting or sleeping cat that breathes more than about 30 times a minute is a real warning sign. This is the single most useful thing you can check at home.
• Labored or open-mouth breathing. Cats almost never breathe through an open mouth or pant like dogs. If yours does, treat it as an emergency.
• Hiding and withdrawal. A cat that suddenly retreats under the bed or stops greeting you may be telling you something is wrong.
• Low energy and less play. Sleeping more, reluctance to jump, or general dullness.
• Reduced appetite or weight loss over weeks.
• Fainting or collapse, sometimes after exertion or a stressful moment.
• Sudden hind-leg paralysis. A cat that cries out and cannot use one or both back legs, with cold or pale paw pads, may have thrown a blood clot. This is covered below and is an emergency.

One thing to note: cats with heart disease rarely cough. Coughing in a cat points more often to feline asthma than to the heart. So with the heart, breathing effort and breathing rate are the more reliable clues, not a cough.

A healthy resting cat usually breathes fewer than 30 times a minute, and often between 15 and 25. A resting rate that is consistently above 30 deserves a vet visit soon. A rate above 40 with visible effort, belly heaving, or an open mouth is an emergency. If your vet has already diagnosed heart disease, keeping a simple log of the sleeping breathing rate is one of the best ways to catch fluid building up early.

• Labored breathing or open-mouth breathing. This often means fluid around or in the lungs. Cats work hard to hide this, so by the time it shows, it is serious.
• Sudden paralysis of the back legs. A clot lodging where the main artery splits to the hind limbs, called a saddle thrombus or aortic thromboembolism, causes sudden, very painful weakness or paralysis of one or both back legs, often with cold paws and pale or bluish pads. Affected cats cry out. This is an emergency and it is genuinely painful, so handle your cat gently and get to a clinic fast.
• Collapse or fainting. Any loss of consciousness needs immediate assessment.

In these moments, do not spend time on an app or a video call. Get to a physical emergency clinic. Keep your cat warm, quiet, and as still as possible on the way, and call ahead if you can so the team is ready.

Heart muscle changes can also be secondary to another problem. Two are worth knowing because they are common and treatable. An overactive thyroid gland (hyperthyroidism) in older cats drives the heart to work too hard and can thicken the muscle. High blood pressure, often linked to kidney disease or thyroid disease, does the same. This is why a vet checking a cat's heart will usually also check blood pressure and run a thyroid blood test. Treating the underlying cause can sometimes improve the heart.

The test that confirms HCM is an echocardiogram, an ultrasound of the heart that lets the vet measure the thickness of the heart walls and see how the chambers move. Supporting tests include chest X-rays to look for fluid, blood pressure measurement, a thyroid blood test in older cats, and sometimes a blood test called NT-proBNP that can flag heart strain. Together these tell the vet whether the heart is the problem, how advanced it is, and what is driving it.

• For a cat in heart failure with fluid in the lungs, a vet uses medicines such as diuretics to clear that fluid and ease breathing.
• For cats judged to be at risk of clots, a vet may prescribe an anti-clotting medicine such as clopidogrel to lower the chance of a saddle thrombus.
• Other heart medicines may be added depending on the exact findings on the echocardiogram.
• If an overactive thyroid or high blood pressure is part of the picture, treating that is a core part of care.

Please do not start, stop, or share heart medicine on your own. Doses are precise and the wrong choice can do harm. Follow-up matters too. Your vet may recheck the heart and ask you to monitor the sleeping breathing rate at home so that a change is caught before it becomes a crisis.

Omelo does not diagnose, treat, or prescribe, and it cannot confirm heart disease. Only a vet with an echocardiogram can do that. And if your cat is struggling to breathe, has collapsed, or has sudden hind-leg paralysis, skip the app and go straight to an emergency vet.

In India, if you would like a licensed vet to weigh in on non-emergency signs before you decide on an in-person visit, you can book a 15-minute video consultation for ₹349 at vet.beomelo.com. A vet can talk through what you are seeing and help you plan the next step, including in-person testing when it is needed.

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