What time of year should I start flea and tick prevention?

Ticks in particular become active once temperatures rise consistently above roughly 4 degrees Celsius (39 degrees Fahrenheit), which in many temperate regions means late winter or early spring, though a run of unusually mild days even in the middle of winter can trigger brief activity.

Fleas that find their way indoors can continue their life cycle in the warm, stable environment of a heated home regardless of the outdoor season, which is a major reason many vets now recommend continuous prevention rather than a seasonal on and off approach.

Regional climate differences are significant enough that a schedule sensible in one location may not fit another, so asking your vet directly about the typical parasite season where you live, and whether your dog's specific circumstances call for year round coverage, gives a far more reliable answer than a generic rule.

Taking a trip to a region with a different climate or a known higher parasite risk, even briefly, can mean your dog needs prevention outside of what would normally apply at home, so mentioning any planned travel to your vet ahead of time lets them adjust the recommendation accordingly rather than assuming your usual local schedule still applies.

Local veterinary clinics often track regional parasite trends through the season and can give more specific, current guidance than a general seasonal rule, particularly useful if your area has seen an unusually warm winter or a known local outbreak.