Dog heat cycle: stages, signs and timing
The four stages of a dog’s heat cycle, how long each lasts, how often a female cycles, and when she ovulates, with the numbers from the Merck Veterinary Manual.
Littero is made by Lucernel.
On this page
Short answer
A female dog usually comes into heat about twice a year, with 4 to 13 months between cycles (7 on average). The visible heat has two parts of about nine days each: proestrus, with bloody discharge and no interest in mating, then estrus, when she accepts the male and ovulates two to three days after the LH peak.
Choose this if
A calendar note is enough to see when a pet female is due into heat again.
Choose the other option if
Littero helps breeders who track several females, progesterone results and breeding dates.
At a glance
| Feature | Calendar notes | Littero |
|---|---|---|
| Records the start of each heat | Yes | Yeson a cycle calendar |
| Shows the interval between cycles | Partlyyou count it | Yes |
| Progesterone results on a chart | No | Yes |
| Whelping window from the mating dates | No | Yesa range, never a single date |
| Several females and their litters | Partly | Yes |
| Works offline | Yes | Yesstored on the device |
The four stages
The Merck Veterinary Manual describes the canine estrous cycle in four stages.
- Proestrus: about 9 days on average (from 2 days to 3 weeks). The vulva swells and there is a bloody discharge; males are attracted but she does not accept mating.
- Estrus: about 9 days on average (from 3 days to 3 weeks). She accepts the male. The discharge often lightens to straw color and the vulva softens. Ovulation happens in this stage, about 2 to 3 days after the LH peak.
- Diestrus: she refuses the male again, the discharge fades and the vulva slowly shrinks. Progesterone stays high, whether or not she is pregnant.
- Anestrus: the resting stage between cycles, usually 1 to 6 months.
How often dogs come into heat
Most females cycle about twice a year. The interval between cycles can range from 4 to 13 months, with an average of 7. Some large breeds, such as Great Danes, normally cycle only every 9 to 12 months.
Recording the first day of each heat shows your own dog’s rhythm, which is more useful than any average when you plan a breeding or a vet visit.
Signs she is in heat
- A swollen vulva and a bloody discharge at the start (proestrus).
- Interest from male dogs, even at a distance.
- Later, standing for the male and moving her tail aside (estrus).
- More frequent urination and changes in mood or appetite in some dogs.
Timing a breeding
Because heat length varies so much, counting days from the first sign of bleeding is unreliable. Breeders and veterinarians time mating with blood progesterone tests, which rise around the LH peak and ovulation, sometimes together with vaginal cytology.
Dogs ovulate even when they are not bred. If you do not plan a litter, keep her away from intact males for the whole heat, and talk to your veterinarian about spaying.
Frequently asked questions
How long is a dog in heat?
The visible heat (proestrus plus estrus) usually lasts about two to three weeks, but each stage can range from a few days to three weeks.
How often do dogs go into heat?
Usually about twice a year. The interval ranges from 4 to 13 months, 7 on average; some giant breeds cycle every 9 to 12 months.
When is a dog most fertile?
During estrus, around ovulation, which comes about two to three days after the LH peak. Progesterone testing tells you when that is.
Can a dog get pregnant while bleeding?
Yes. Discharge can continue into estrus, when she is fertile, so bleeding is not a sign that she cannot conceive.
Is Littero available?
Littero is in development for iPhone.
Our pick
Littero, the kennel book for dog breeders
Littero keeps each female’s heat cycles and progesterone results on a calendar and a chart, and turns the mating dates into a whelping window, never a single fake date.
- Heat cycles and progesterone charts
- Mating-to-whelping date ranges
- Litters and puppy weigh-ins
