Flea and tick protection in a temperate climate runs from March to November, dosed every 28 days rather than once a month, with the house treated in 2 rounds 14 days apart. The 24-hour line matters most: a tick removed within 24 hours of attaching has very little chance of passing on the bacteria behind Lyme disease, and most cats are bitten on the head or neck where the owner never looks.
The 3–11 Calendar
Flea eggs hatch when the floor temperature holds above about 15 °C, and ticks start questing at 4–5 °C, so the season opens earlier than the first warm weekend. Write 12 dose dates on the calendar — March 1, then every 28 days through mid-November — and treat November as part of the season, not the end of it. A single missed dose in May costs 3 weeks of catching up, because the product has to be present before the flea bites, not after.
Every 28 Days, Not Every Month
Dose on day 0, 28, 56 and so on. Twelve doses at 28-day spacing covers 336 days, which is 29 days short of a year — the reason a monthly habit drifts and leaves a 4–7 day gap by autumn. Put the date in the phone with a 2-day early reminder, and dose on the same weekday each cycle. Never split a dose to stretch it, and never re-dose early to make up for a late one: wait out the interval, then resume the 28-day clock.
| Cat weight | Spot-on volume | Dose day | Next dose | House round |
|---|---|---|---|---|
| 1–2.5 kg | 0.25 ml | Mar 1 | Mar 29 | Mar 1 and Mar 15 |
| 2.5–5 kg | 0.5 ml | Mar 1 | Mar 29 | Mar 1 and Mar 15 |
| 5–7.5 kg | 0.8 ml | Mar 1 | Mar 29 | Mar 1 and Mar 15 |
| Over 7.5 kg | 1.0 ml, vet-checked | Mar 1 | Mar 29 | Mar 1 and Mar 15 |
| Kitten under 8 weeks | Vet only, no OTC product | Per vet | Per vet | Mar 1 and Mar 15 |
The volumes above show how weight bands work, they are not a prescription: read the tube that matches your cat's band, and weigh the cat in February, because a 300 g gain can cross a boundary and under-dosing is how resistance starts.
The 24-Hour Tick Line
Check the cat every evening during the season, 5 minutes with your fingers: ears, the fold at the base of the ear, under the chin, armpits, between the toes, and around the tail base. A tick starts as a 2 mm speck and grows over 3–7 days, so a 2 mm find is a fresh bite and a 10 mm find is a week old. Remove with fine tweezers held flat against the skin, pull straight up without twisting, then clean with an alcohol wipe and photograph the site. Write the date down. A red ring or a scab that spreads over the next 14 days is a vet call; so is any cat that goes off food for 2 days after a bite.
Two Environment Rounds, 14 Days Apart
Roughly 5% of a flea problem is the adult fleas on the cat and the rest is eggs, larvae and pupae in the carpet, under the sofa and in the cracks of a wooden floor. That is why one treatment never works: the pupae survive a spray and hatch 7–14 days later. Round 1 on day 0, round 2 on day 14, both after a full vacuum. Vacuum daily for 7 days after each round and empty the canister outside; wash all bedding at 60 °C, and throw out the vacuum bag rather than leaving it in a cupboard. A third round at day 28 is worth it in a multi-cat home. If the carpet is older than 5 years, add a 4th round at day 42, because dense pile holds pupae longer than a smooth floor and the vacuum only reaches the top 3 mm.
Why Spring Is the Gap
The cat has been indoors since November, the last dose was sometime in October, and nothing has bitten for 5 months, so the March dose feels optional. It is not: a single female flea can lay around 40–50 eggs a day, and a cat that picks up 2 fleas at a March window ledge seeds the carpet with several thousand eggs before the first itch shows. Cats rarely scratch the way dogs do, so the first sign is often a fine black grit on the sleeping spot rather than a scratching cat.
The 6-Point Spring Check
- Weigh the cat in February and re-read the weight band on the box.
- Dose on day 0 and write the next 11 dates on a calendar before the first tube is open.
- Vacuum and wash bedding on the same day as round 1, then vacuum daily for 7 days.
- Run round 2 at day 14 and a third at day 28 in a 2-cat home.
- Comb the cat with a fine flea comb over a white sheet once a week; grit means live fleas.
- Check the ears and neck by hand every evening, 5 minutes, and log any tick with the date.
When the Calendar Is Not Enough
Three signals mean the plan has failed and a vet should see the cat: live fleas on the comb for 14 days after round 2, a bald patch with broken hairs at the tail base, or a tick found on a cat that has been dosed on schedule. Do not double the dose or stack 2 products — permethrin, a common dog spot-on, is toxic to cats and is the classic poisoning case in a multi-pet home, so check every tube against the toxicity list. The summer peak, when tick numbers run 2–4 times the spring level, is covered in summer tick season.
Terms mentioned in this article
Frequently asked
How often should cats be treated for fleas and ticks?
Every 28 days from March to November in a temperate climate, which is 12 doses and 336 days of coverage. Monthly dosing drifts by 4–7 days a year, and that gap is enough for a flea to lay 40–50 eggs a day on the cat.
How fast must a tick be removed from a cat?
Within 24 hours of attaching. The risk of passing on Lyme bacteria rises sharply after that window, so check the ears, chin, armpits and toes by hand every evening for 5 minutes, and log the date of any tick you find.
Why do I need two rounds of house treatment?
About 95% of the flea problem is eggs, larvae and pupae in carpet and floor cracks, and pupae survive a spray and hatch 7–14 days later. Treat on day 0 and day 14, vacuum daily for 7 days after each round, and wash bedding at 60 °C.