Flea and Tick Treatment Timing Calculator
Work out when the next flea and tick dose is due, and whether you should be treating year-round in your climate.
Next dose due
Sun, 20 Sept 2026 in 10 days
| Dose | Date |
|---|---|
| Dose 1 | Sun, 20 Sept 2026 |
| Dose 2 | Tue, 20 Oct 2026 |
| Dose 3 | Thu, 19 Nov 2026 |
| Dose 4 | Sat, 19 Dec 2026 |
| Dose 5 | Mon, 18 Jan 2027 |
| Dose 6 | Wed, 17 Feb 2027 |
Treat all year. Fleas survive indoors in any climate, and ticks are active whenever the ground is above about 4 degrees Celsius.
How this is calculated
The next dose is simply the last treatment date plus the product's protection interval. What matters is using the interval for the product you actually bought, because they vary by nearly a factor of eight.
next dose = last treated + product interval in days Protection intervals by product
| Product | Interval | Doses per year |
|---|---|---|
| Monthly spot-on | 30 days | 12.2 |
| Monthly oral tablet | 30 days | 12.2 |
| 12-week oral tablet | 84 days | 4.3 |
| 8-month collar | 243 days | 1.5 |
| 6-month injection | 182 days | 2 |
Climate guidance
| Climate | Recommendation |
|---|---|
| Mild or warm year-round | Treat all year. Fleas survive indoors in any climate, and ticks are active whenever the ground is above about 4 degrees Celsius. |
| Cold winters, warm summers | CAPC still advises year-round treatment. Indoor heating keeps flea populations alive through winter, and ticks emerge on any mild day. If you do stop, restart well before the first spring thaw. |
| Tropical or subtropical | Year-round treatment is essential, and the pressure is constant. Consider a product that also covers ticks and mosquitoes if heartworm is present locally. |
Sources
Why the house matters more than the dog
An adult flea you can see represents roughly twenty more you cannot, sitting in the carpet as eggs, larvae or pupae. Pupae are effectively armoured; no product reaches them, and they can wait months for vibration and warmth before hatching. That is why an infestation appears to come back after treatment, and why clearing one takes about three months of consistent effort rather than one application.
Wash all bedding at 60 degrees, vacuum daily including under furniture and along skirting boards, empty the vacuum outside, and treat every cat and dog in the household on the same day. Missing one pet keeps the cycle running.
Ticks
Check your dog by hand after every walk in long grass or woodland, paying attention to the head, ears, neck, armpits and between the toes. Remove any tick promptly with a hook, twisting it free rather than pulling, and never with fingers, tweezers alone, or by burning it. Prompt removal matters because several tick-borne infections need the tick attached for a day or more before they transmit.
Common questions
How often should I treat my dog for fleas and ticks?
It depends entirely on the product. Monthly spot-ons and tablets last 30 days, some oral tablets last 12 weeks, collars up to 8 months, and injections around 6 months. Set a reminder from the date you last treated rather than trying to remember.
Do I need flea treatment in winter?
Yes, in almost every climate. Fleas complete their life cycle indoors on central heating and do not care what the weather is doing. Ticks become active whenever the ground temperature rises above about 4 degrees Celsius, which happens on mild winter days in most temperate regions.
I treated my dog and still see fleas. Why?
Only about 5% of a flea population lives on the dog. The rest is eggs, larvae and pupae in carpets, bedding and floorboards. Treatment on the dog kills adults as they jump on, so you keep seeing new ones for up to three months while the environmental stages hatch out. Wash bedding hot, vacuum daily and treat every pet in the house.
What happens if I am late with a dose?
Protection lapses at the end of the stated interval, not gradually. A few days late usually causes no harm; a few weeks late is long enough for a household infestation to establish, which then takes about three months to clear.
Can I use a cat product on my dog, or the other way round?
Never use a dog product on a cat. Many contain permethrin, which is severely toxic and often fatal to cats. If you have both species, check the label of anything you apply and keep treated dogs away from cats until it dries.
How quickly do ticks transmit disease?
Transmission risk rises the longer a tick stays attached, and for several tick-borne diseases it takes 24 to 48 hours. Check your dog daily in tick season and remove any you find with a proper tick hook, twisting rather than pulling.