Dog Heat Cycle Tracker
Predict your dog's next heat cycle and plan ahead. Get clear proestrus and estrus windows so you're never caught off guard.
Planning Tool Only Heat cycles vary significantly between individual dogs. This tool provides estimates based on averages and should not be used for breeding decisions. Consult your veterinarian for accurate fertility timing.
Why track your dog's heat cycle?
Tracking the heat cycle helps you anticipate behavioural changes, prevent unwanted pregnancies, and spot abnormal cycles that could indicate a health problem. It is also essential for any responsible breeding plan, although a vet should always confirm the fertile window for breeding.
How long is a dog's heat cycle?
Most dogs cycle every 6 months (180 days), but the range is wide — anywhere from 4 to 12 months between cycles. Small breeds tend to cycle more frequently, while giant breeds can go a full year between heats. The heat itself usually lasts 2 to 4 weeks (about 21 days on average).
The two main phases
- Proestrus (≈ first 9 days): Vulva swelling and bloody discharge. The female attracts males but is not receptive yet.
- Estrus (≈ days 10–21): The fertile window. Discharge lightens, and the female actively accepts males. Ovulation usually happens 2–3 days after estrus begins.
After estrus comes diestrus (around 60 days, whether or not she is pregnant) and then anestrus, the long resting phase before the next heat.
How accurate is this tracker?
Heat cycles vary significantly between individual dogs, so this tool gives an estimate based on averages. It is not precise enough for breeding decisions — for accurate fertility timing, your veterinarian can run progesterone tests to identify ovulation within 24–48 hours.
When to worry
Contact your vet if your dog's heat lasts more than 4 weeks, if you see pus-like or foul-smelling discharge (a sign of pyometra, which is a life-threatening uterine infection), or if cycles become very irregular. Pyometra typically occurs 4–8 weeks after a heat and is a medical emergency.
FAQs
A full cycle (heat to heat) usually lasts about 6 months, but it can range from 4 to 12 months depending on the breed and individual dog. The heat itself lasts 2–4 weeks, with most dogs averaging around 21 days.
Common signs include a swollen vulva, bloody or pinkish discharge, more frequent urination, increased attention from male dogs, mood swings, and tail-flagging when touched near the back. Some dogs also become more clingy or irritable.
Most female dogs have their first heat between 6 and 12 months of age, but small breeds can start as early as 4 months and large or giant breeds may not cycle until 18–24 months. The first cycle is often irregular.
The fertile window is the estrus phase, typically days 10 through 21 of the heat. Ovulation usually happens 2–3 days after estrus begins, and the egg remains viable for about 2 days. For accurate breeding timing, ask your vet for a progesterone test.
Yes. The first one or two cycles after a dog reaches maturity are often irregular. Older dogs may also have longer intervals. If cycles become very erratic, are skipped for more than a year, or are accompanied by abnormal discharge, contact your vet to rule out hormonal or uterine problems.
Pyometra is a life-threatening infection of the uterus that typically appears 4–8 weeks after a heat in unspayed females. Signs include pus-like vaginal discharge, lethargy, fever, excessive thirst, and a swollen abdomen. It is an emergency — go to a vet immediately.
