How Often Do Dogs Go Into Heat?
'When is her next heat?' is one of those questions where the textbook answer (every 6 months) is technically true and practically often useless. The real range is wide. Small breeds may cycle every 4 months, giant breeds sometimes only once a year, and the first cycles of a young dog are often irregular. Your dog has her own rhythm, and the best way to know it is to track it.
The four stages of the canine heat cycle
Proestrus (7-10 days): Vulvar swelling and bloody discharge. Males are interested, she is usually not.
Estrus (5-10 days): The discharge lightens, and she is fertile and receptive. This is the stage that matters for breeding, and for avoiding unwanted breeding.
Diestrus (about 2 months): The cycle winds down hormonally, whether she is pregnant or not.
Anestrus (3-5 months or more): The quiet phase before it starts again.
The visible heat, meaning the part you notice at home, typically lasts 2-4 weeks in total.
NOTE: The weeks to months after a heat are the highest-risk window for pyometra, a life-threatening disease of the uterus. Pyometra is a bacterial infection that takes hold after the hormonal changes of the cycle alter the environment inside the uterus. If your intact female drinks noticeably more, seems lethargic, has discharge or a swollen belly following a heat, she should see a vet the same day. I would rather examine ten healthy dogs than miss one pyometra
Why I ask owners to track heats
Prediction. Once you have two or more logged heats, the next one becomes roughly forecastable. That matters for planning holidays, shows, training courses and boarding.
Breeding. If a litter is the plan, timing matters down to days, and knowing her normal cycle length is step one before any progesterone testing.
Health. A cycle that suddenly shortens, lengthens or becomes irregular is worth mentioning to your vet. "When was her last heat?" is a question I ask at almost every consultation. Owners rarely remember precisely.
How the prediction works in practice
The math is simple: average the intervals between her previous heats and project forward. The complication is that dogs are not perfectly regular, so a prediction is a window, not a date. In PetVitality you log each heat with the start date (duration and notes are optional), and after two heats the app calculates her regularity and shows the expected next heat as a date window with a countdown. When the window opens, it tells you to keep an extra eye out, and you can put the whole thing in the app's calendar with one tap.
A few practical tips
Log the first day you notice swelling or discharge, even if you are unsure. You can adjust later.
Note anything unusual: heavier bleeding, longer cycle, strong behaviour changes. Patterns in these notes are useful to your vet.
If you have decided not to breed her, talk to your vet about spaying. It removes both the heats and the pyometra risk, and the timing of the surgery is usually planned relative to her cycle.
