Female dogs are usually in heat (the fertile part of their cycle) for about 2–3 weeks, with most staying in heat around 14–21 days.

Quick Scoop: How long does dogs stay in heat?

The short answer

For most female dogs, a heat (also called “season” or “estrus”) lasts about 2–4 weeks , with the most common range being 12–21 days.

During this time, she can attract males and, for part of it, can become pregnant.

Mini breakdown of the heat timeline

Think of your dog’s heat as a short, dramatic “season” that moves through phases:

  1. Early heat (proestrus) – about 7–10 days
    • Swollen vulva, bloody discharge, lots of licking, more peeing/marking.
 * Most males are very interested, but many females are not ready to mate yet.
  1. Fertile heat (estrus) – about 5–10 days
    • Discharge becomes lighter or more watery, often pink or straw-colored.
 * This is when she is most fertile and may stand and “flag” (move her tail aside) for male dogs.
  1. After heat (diestrus) – up to ~2–3 months
    • Bleeding and swelling resolve, she stops accepting males, but hormones are still shifting.
 * If she was bred, this is when pregnancy continues; if not, her body just winds down.
  1. Resting phase (anestrus) – about 4 months on average
    • Her body is “off-season” between heats, often about 4–6 months for many dogs, sometimes longer.

Most female dogs come into heat about twice a year , but small breeds may cycle three times a year, and some large breeds only once a year.

Simple example timeline

If your dog’s heat seemed to start on March 1 (you first notice swelling or spotting):

  • March 1–8: Early heat, more bleeding, swelling, behavior changes.
  • March 8–18: Fertile window; bleeding usually lighter, she may accept males.
  • Around March 18–22: Signs calm down; she’s effectively out of heat, but you still treat her as fertile for the full 3–4 weeks to be safe.

Key signs she’s in heat

  • Swollen vulva.
  • Bloody or pinkish discharge that later becomes lighter/watery.
  • More frequent urination and marking.
  • Attracting male dogs, even from far away.
  • Possible behavior shifts: clingy, restless, distracted, sometimes cranky.

Safety tips during heat

  • Keep her away from intact male dogs for at least 3–4 weeks from the first sign of heat to avoid an accidental pregnancy.
  • Use a leash outdoors, even in fenced areas; determined males can find ways in.
  • Consider doggy diapers or washable covers if bleeding is messy at home.
  • Call your vet if:
    • Bleeding is extremely heavy or lasts much longer than 3–4 weeks.
    • She seems very unwell (fever, extreme lethargy, foul-smelling discharge).

“Latest news” & forum chatter angle

Recent pet-health articles and vet Q&As in early 2026 still say roughly the same thing: plan on around three weeks of heat , but don’t be surprised if your dog is slightly shorter (about 10–12 days) or longer (close to 4 weeks).

On dog forums and AskVet-style communities, owners often talk about planning vacations or daycare around that 2–3 week window and usually play it safe by treating their dogs as fertile for the full 21 days from the first spotting.

TL;DR: Most dogs stay in heat about 2–3 weeks , sometimes up to 4 weeks , and they usually go through this about twice a year.

Information gathered from public forums or data available on the internet and portrayed here.