Do I really need flea, tick and worm treatment all year round — and can I split the dog's tube for the cat?

Take the cat out of that plan first, because this part is genuinely life and death: never put a dog's flea product on a cat, not even half of it. Several compounds used in dog treatments — permethrin is the notorious one — are severely toxic to cats. Cats have died after being given a well-meant share of the dog's spot-on, and some have been poisoned simply by grooming or sleeping against a dog treated hours earlier. If it ever happens by accident, that is an emergency: go to your vet or your nearest emergency clinic straight away and take the packaging with you. These products are licensed by species and by weight band, and that choice belongs to your vet, not to a spare tube.

Whether you treat year-round depends on your climate, your heating, and what those two actually do. Fleas breed happily indoors in a heated home right through the cold months, so seasonal versus year-round is a decision you make with your vet for your region, not a universal rule. And not seeing a flea means very little — the animal carries only a small fraction of the population.

Two things change the outcome more than the brand does. First, treat every pet in the household, because the untreated one keeps the cycle running, and treat the house too: the eggs and larvae are in the carpet, the bedding and the sofa. Hot-wash bedding and vacuum thoroughly and repeatedly, right into the edges.

Second, ticks. After walks, run your hands over the dog — armpits, groin, ears, between the toes, under the collar. Lift any tick out whole with a proper tick hook. Don't burn it, don't smother it in oil, don't squeeze the body.

Worming frequency is risk-based: a hunting cat, raw feeding, small children in the house all push it up, and your vet sets it. Some worms pass to people, so pick faeces up promptly and wash your hands.