Heart problems in dogs and cats rarely announce themselves. What owners notice is a dog slowing down on the same walk, a cough that starts at night, or a cat breathing faster while asleep. None of those look dramatic, and all of them are worth mentioning, because the earlier this is picked up the more can be done about it.
Autumn is when it tends to show
Walks get longer and cooler in the autumn after a hot summer, so dogs do more. That is exactly when reduced exercise tolerance becomes visible: the dog who used to lead the walk now lags on the way home, or stops and sits halfway up the hill.
It is easy to file that under getting older. Sometimes it is. Often it is something we can identify at an examination, and the difference matters because early changes are far more manageable than late ones.
What a murmur is, and what it is not
A murmur is a sound, not a diagnosis. Normally a stethoscope picks up two clean sounds as the valves close. When blood becomes turbulent, usually because a valve is leaking or a chamber has changed shape, that turbulence makes an extra whooshing noise.
Murmurs are graded by loudness, and loudness alone does not tell you how serious things are. A soft murmur can matter a great deal and a louder one can be trivial. Some puppies and kittens have innocent murmurs that disappear as they grow. Some cats with significant heart change have no murmur at all, which is why what you see at home carries real weight.
What a murmur does mean is that it is worth looking further. That usually involves imaging of the chest, sometimes an ultrasound of the heart, and often blood pressure and blood work, all of which our urgent care and regular appointments can arrange depending on how your pet presents.
The signs worth reporting
In dogs:
- Reduced stamina: lagging, stopping, or wanting shorter walks
- A cough, particularly at night, on lying down, or after excitement
- Faster breathing at rest, or more effort with each breath
- A swollen or firm abdomen
- Restlessness at night, or an inability to settle
- Fainting or collapse, especially during exercise or excitement, which is always urgent
- Pale or bluish gums
In cats:
- Faster breathing while sleeping or resting, often the only sign
- Open-mouth breathing, which in a cat is an emergency at any time
- Hiding, reduced appetite, or general withdrawal
- Sudden pain, crying out, or dragging a back leg, which needs immediate care
Cats conceal heart problems more completely than any other species we see, and that last sign is the one every cat owner should know. Sudden weakness or paralysis of the back legs with obvious pain can be a clot, and it needs help within minutes rather than hours. The affected legs usually feel cold to the touch and the pads or nail beds look pale or bluish.
The most useful thing you can do at home
Count the sleeping breathing rate. It takes thirty seconds, needs no equipment, and is one of the most useful things you can measure at home, because it picks up fluid building in the chest before anything else does.
With your pet properly asleep and settled, not dreaming or panting, count each rise and fall of the chest for thirty seconds and double it. Most healthy dogs and cats sit comfortably under about thirty breaths a minute while asleep, and many are well below that.
Do it a few times over a week to learn your own pet’s normal, and note it somewhere. A rate that climbs above that range, or a steady upward trend over several days in a pet already known to have a heart condition, is a reason to phone rather than wait for the next appointment. It is often the earliest sign that fluid is building.
Who is more likely to be affected
- Small breed dogs such as cavaliers, chihuahuas, dachshunds, poodles and terriers, where valve changes are the usual pattern and become more common with age
- Large and giant breeds including dobermans, great danes, boxers and wolfhounds, where the muscle itself is more often involved
- Older pets generally
- Cats of any age, including young adults, since the common feline heart condition can be present in an outwardly healthy cat
- Overweight pets, not because the weight itself causes the condition, but because it masks the early exercise intolerance that would otherwise give it away
Weight is the part owners have most control over. Our guide to autumn weight gain in dogs and cats covers how to check body condition at home, and it links directly to how hard the heart has to work.
Older pets benefit from an examination twice a year rather than once, because six months is a long time at that stage and a murmur that was not there in spring can be obvious by autumn. Our senior care service is built around exactly that rhythm.
Frequently asked questions
My vet heard a murmur but said not to worry. Should I?
Not necessarily worry, but do follow it up as advised. Murmurs are graded and monitored, and many pets live for years with one that never causes a problem. What matters is knowing which kind you are dealing with, which usually means imaging through our diagnostics service at some point rather than listening alone.
My dog coughs only at night. Is that the heart?
It might be, and it might be an airway problem, which is common in small breeds and looks similar. A night-time or lying-down cough is worth an examination either way. Count the sleeping breathing rate for a few days beforehand and bring the numbers with you.
Can heart problems be reversed?
Most are managed rather than reversed, and management can be very effective. Pets diagnosed early and monitored properly often do well for a long time, which is the whole argument for mentioning the small changes rather than waiting.
How do I count breathing if my dog pants constantly?
Wait until they are genuinely asleep, since panting makes the count meaningless. If your dog pants at rest and cannot settle, that itself is worth reporting.
Do cats get murmurs too?
Yes, and the relationship is less predictable than in dogs. Some cats with a loud murmur have a structurally normal heart, and some with significant change have no murmur. That is why a resting breathing rate at home is so useful in cats.
Is exercise bad for a pet with a heart condition?
Usually not, within limits set for your individual pet. Gentle, regular activity generally suits them more than doing nothing, while hard bursts of exercise are what we tend to advise against. Ask us specifically rather than guessing, because it depends on the stage.
Speak to the team at Tynehead Animal Hospital
If your pet is slowing down, coughing at night, or breathing faster in their sleep, phone us and book an examination. A cat breathing with an open mouth, or a pet who suddenly cannot use their back legs, should not wait: come straight in, or go to the nearest open emergency hospital if we are closed.
Published by the team at Tynehead Animal Hospital.
This article is for general educational purposes only and is not a substitute for an in-person veterinary examination or advice about your individual pet. If you have an urgent concern about your pet, contact Tynehead Animal Hospital or your nearest emergency veterinary hospital right away.
Tynehead Animal Hospital
8645 160 St Unit 112, Surrey, BC V4N 1G4
Phone: (604) 547-2227
Email: info@tyneheadanimalhospital.ca
Hours: Monday to Friday 9:00 AM to 7:00 PM; Saturday and Sunday 9:30 AM to 4:00 PM