Dogs don’t have “periods” exactly like humans, but their heat (estrus) cycle — the time when they bleed and can become pregnant — typically lasts about 2–4 weeks in total, with visible bleeding usually around 1–3 weeks for most dogs.

What “on their period” means

When people say a dog is “on her period,” they’re almost always talking about her being in heat (in season), which is her fertile cycle.

During this time, she may have vaginal swelling, a bloody or pink discharge, and extra interest from male dogs.

How long it usually lasts

Most unspayed female dogs follow this general pattern:

  • Proestrus (early heat, obvious bleeding): about 7–10 days on average, but can be a few days up to about 2 weeks.
  • Estrus (standing heat, may bleed less): about 7–10 days on average, sometimes up to about 2–3 weeks.
  • Altogether, owners often notice “being on her period” for roughly 2–4 weeks before things fully settle down.

How often it happens

  • Most dogs come into heat about every 6–7 months, often twice a year.
  • Smaller breeds may cycle a bit more often; very large breeds may go less often.

Spaying stops these cycles completely and prevents pregnancy and certain health risks like pyometra and some cancers.

When to call a vet

Contact a vet promptly if:

  • Bleeding is extremely heavy or lasts longer than about a month.
  • She seems very tired, in obvious pain, has a bad-smelling discharge, or runs a fever.
  • You are unsure if what you’re seeing is a normal heat or something else.

For your post’s SEO angle, your key phrase “how long are dogs on their period” maps to “how long are dogs in heat,” and a clear answer is: “Most dogs are in heat and may bleed for around 2–4 weeks, with the most noticeable bleeding usually 1–2 weeks.”