Fleas, ticks and worms: staying ahead of the parasites, and the one product mistake that kills cats

Fleas, ticks and worms are the routine background threat of pet ownership, unglamorous and easy to put off.

The reason to stay ahead of them is that prevention is a great deal easier than the cure. A flea problem is invisible until it's an infestation, a tick can pass on disease in the time it stays attached, and worms do their damage quietly.

A modest regular routine handles all three. Which products and how often are questions to settle with your vet, because the right answer depends on where you live and how your pet lives.

The rule that comes first: never use a dog product on a cat

Before anything else, the safety point that matters most.

Some flea treatments made for dogs contain permethrin, which is a useful ingredient for dogs and highly toxic to cats. A dog product applied to a cat, or a cat grooming a recently-treated dog it lives with, can cause severe, sometimes fatal poisoning.

Only ever use a product on the species it's labelled for, keep a treated dog apart from the household cat until it has dried, and if a cat is ever exposed to a dog flea product, treat it as an emergency and phone the vet at once.

This one mistake is common and entirely avoidable. It happens most often in two ways: a household buying one large-dog pipette to split between several animals, and a cat that sleeps pressed against a dog treated that morning. Both are easy to prevent once you know.

Fleas: why you treat before you see them

By the time you spot fleas on the animal or in the house, the visible fleas are a small fraction of the problem — the rest is eggs and larvae worked deep into carpets, bedding and floorboards.

That's why flea control is a prevention routine and not a reaction: regular treatment keeps the animal from seeding the house in the first place.

If an infestation does take hold, clearing it means treating every pet in the home at once, washing bedding hot and vacuuming thoroughly and repeatedly, because the household stages have to be broken along with the ones on the animal.

Clearing an infestation, properly

Worth setting out in order, because the commonest failure is doing most of it and wondering why the fleas came back in a fortnight.

Treat every animal in the house on the same day, with a product suited to each species, including the ones showing no signs. A cat that isn't scratching is still part of the population.

Wash all bedding — the animals' and yours if they sleep on it — at the hottest temperature the fabric allows, and keep doing it weekly for a month.

Vacuum daily for at least a fortnight, paying attention to skirting boards, under furniture, the edges of carpets and any cracks in floorboards, which is where larvae retreat. Empty the vacuum outside each time. The vibration also encourages dormant pupae to hatch, which sounds counterproductive and is exactly what you want — hatched fleas meet the treatment, dormant ones don't.

Expect it to take a month or two rather than a week, and expect to see fleas during it. Pupae can lie dormant in a carpet for months and hatch long after everything else has been dealt with, which is why an infestation that seems to relapse usually hasn't — it's finishing.

A household spray for the environment is worth it in a bad case, and it's the one place to read the label carefully with a cat in the house.

Ticks: the prompt, correct removal

Ticks matter less for the bite than for what they can transmit while attached, and the risk rises the longer one stays on, so the job is to find them early and remove them properly.

Check your dog after walks in long grass, woodland or moorland, running your hands over the body for anything small and firm. The places to check carefully are the ones people miss: inside and behind the ears, around the eyes and muzzle, in the armpits and groin, and between the toes.

Remove a tick with a proper tick-removal tool, twisting it out whole and avoiding any squeezing, pulling or burning — the old folk methods make it worse by causing the tick to regurgitate. If you aren't confident, a vet or nurse will do it.

Afterwards, note the date. If your dog becomes lame, feverish, lethargic or off its food in the following weeks, that date is genuinely useful information for a vet, and it's the sort of thing nobody remembers without writing it down.

In tick country the preventive products earn their place, which is another question for the vet about your specific region.

Worms: the ones you cannot see

Worming is the easiest of the three to neglect because a wormed animal looks exactly like an unwormed one until the burden is heavy.

Different worms arrive by different routes — from the environment, from fleas, from hunting and eating prey, and passed from a mother to her litter — which is why puppies and kittens need worming more often than adults, and why a keen hunter or a dog that scavenges needs more attention than a homebody.

Lungworm in particular, picked up from slugs and snails, is serious and worth asking your vet about specifically if it's present where you live. It isn't covered by every routine wormer, which is precisely the sort of gap that catches people out.

The part that matters for people

Some of these parasites can pass to humans, and it deserves a plain paragraph instead of being left implied.

Roundworm eggs shed in animal faeces can infect people, and children are most at risk because of how they play and what ends up in their mouths. The risk is low and the consequences occasionally serious, and it's the main reason routine worming isn't optional in a household with young children.

The practical measures are dull and effective: pick up faeces from the garden promptly, wash hands after handling animals and before eating, cover sandpits, and keep to the worming interval your vet sets.

Fleas bite people too — usually around the ankles — and some tick-borne diseases affect humans as well as dogs, which is another reason to check yourself after the same walks you check the dog after.

Building the routine so it actually happens

The reason people fall behind isn't disagreement with any of the above; it's that a treatment due every four weeks is exactly the interval a human brain fails to track.

Two things fix it. Put it in a calendar with a repeating reminder, on the same day of the month, for every animal in the house. And consider a practice health plan, which bundles the treatments into a monthly payment and posts or hands them to you on schedule — the administration is most of what you're buying, and for many households it's worth it.

Keep a note of what you gave and when, somewhere you'll find it. A vet asking what your dog was last treated with, and with what, gets a shrug far more often than an answer.

The whole routine is best set up as a plan with your vet instead of assembled from guesswork or whatever is on the shop shelf, because the products, the intervals and which parasites to prioritise all depend on your location and your animal. Fold it into the same early-ownership admin as vaccination — and note that a tapeworm treatment on a fixed schedule is a specific requirement for bringing a pet across some borders, so it connects to travel plans too.