Count their breathing

When a heart starts to fail, fluid can build up in or around the lungs, and the first thing that changes is how fast a pet breathes at rest. That is why vets ask owners of dogs and cats with heart disease to count the sleeping breathing rate at home, often every day.

Count only when your pet is asleep or completely relaxed, in a room that is not hot. Panting, purring, dreaming and sniffing all spoil the count. One rise and one fall of the chest is one breath.

Most resting dogs and cats take 30 breaths a minute or fewer. One high reading after exercise or in a warm room means little. A sleeping rate that is above 30 on repeat counts, or that is creeping up over several days, is the signal to call your vet. Your vet may give you a different target for your own pet; use theirs.

Breathing that looks like hard work, with the belly heaving, the neck stretched out, the mouth open in a cat, or gums that are pale, grey or blue, is an emergency whatever the count says.