If your female dog is in heat for the first time, the changes in her behaviour and physical condition can be surprising — particularly if you were not expecting it. Understanding what is happening, how long it lasts, and how to manage it safely makes the experience significantly less stressful for both of you.
What Does “In Heat” Mean?
Being “in heat” (or in season) refers to the fertile phase of a female dog’s reproductive cycle — the period during which she can become pregnant. This is called the oestrus cycle, and it occurs approximately every 6 months in most breeds, though this varies.
Smaller breeds may cycle more frequently (every 4–5 months); larger breeds less so (every 8–12 months). Some giant breeds only cycle once per year.
At What Age Do Dogs First Come Into Heat?
Most female dogs experience their first heat between 6 and 12 months of age, though larger breeds may not cycle until 18–24 months. The first heat can occur earlier than many owners expect — which is one reason early spaying is recommended.
Signs Your Dog Is in Heat
Physical signs:
- Swollen vulva — often the first visible sign
- Bloody or straw-coloured vaginal discharge
- Frequent urination — she is scent-marking to attract males
- Excessive licking of the genital area
Behavioural signs:
- Restlessness and increased activity
- Clinginess or, conversely, unusual aloofness
- Flagging — holding the tail to one side when touched near the hindquarters
- Increased interest from male dogs (and increased interest in them)
- Attempting to escape the home or garden — this instinct can be very strong
How Long Does a Dog Stay in Heat?
The complete oestrus cycle has four stages, but the active heat period during which your dog can become pregnant typically lasts 7–10 days, within an overall cycle of 2–4 weeks.
| Stage | Duration | What Happens |
|---|---|---|
| Proestrus | 7–10 days | Swelling, bloody discharge, males attracted but female not yet receptive |
| Oestrus | 5–10 days | Fertile period, female receptive to mating |
| Dioestrus | 60–90 days | Post-heat, whether pregnant or not |
| Anoestrus | 4–5 months | Resting phase before next cycle |
How to Manage a Dog in Heat
Prevent Unwanted Pregnancy
This is the priority. An intact male dog can smell a female in heat from remarkable distances — up to 3 miles in some cases. During the fertile window:
- Keep your dog on a lead at all times outdoors — even in your own garden if it is not securely fenced
- Check fencing for gaps or weaknesses — a determined male will find them
- Do not leave her unsupervised outside, even briefly
- Avoid dog parks and areas where intact male dogs are likely to be present
- Inform your neighbours if they have intact male dogs
Manage Discharge
Vaginal discharge during heat can stain furniture and bedding. Dog heat pants (a type of sanitary garment) contain the discharge and are widely used by owners of indoor dogs in heat.
Wash bedding regularly during this period. The discharge is normal and does not require any cleaning of the dog beyond normal hygiene.
Manage Behaviour Changes
Restlessness, clinginess, and attempts to escape are all driven by hormonal changes — not defiance. Extra exercise helps burn off some of the restless energy, though always on lead. Mental stimulation through puzzle feeders and training sessions also helps. See our enrichment toys for dogs guide for ideas.
If your dog becomes anxious during heat, our dog anxiety guide covers calming approaches that are safe during this period.
Keep Male Dogs Completely Separated
If you have an intact male dog in the same household, they must be completely separated during the female’s entire heat cycle — not just the visibly fertile days. Male dogs can become highly stressed, stop eating, and injure themselves or others attempting to reach a female in heat. This is not a situation that can be managed by supervision alone — physical separation in different parts of the house is necessary.
Should You Let Your Dog Have One Litter Before Spaying?
No — there is no medical or behavioural benefit to allowing a dog to have a litter before spaying. This is a persistent myth with no veterinary support. Spaying before the first or second heat provides the greatest health benefits, including significant reduction in mammary tumour risk.
Can You Stop a Dog’s Heat With Medication?
Veterinary medications exist that can suppress or delay heat cycles — these are sometimes used in working dogs or show dogs where timing is important. These are prescription-only and carry health risks with long-term use. They are not a substitute for spaying and should only be used under veterinary guidance for specific situations.
The Permanent Solution — Spaying
The most effective way to manage heat cycles permanently is spaying — surgical removal of the ovaries and uterus. This eliminates heat cycles entirely, prevents unwanted pregnancy, and provides significant health benefits including dramatically reduced mammary cancer risk.
Most vets recommend spaying between heat cycles rather than during one, as the increased blood supply to the reproductive organs during heat makes the surgery more complex. Discuss timing with your vet.
How to Control a Dog in Heat — FAQ
Can a dog get pregnant on her first heat? Yes — a dog can become pregnant on her very first heat cycle, even at 6 months of age. This is one of the reasons early spaying is recommended.
How do I know when my dog’s fertile window is? The fertile window is typically during the oestrus stage — when discharge becomes lighter or straw-coloured and your dog actively seeks male attention and flags her tail. However, predicting the exact fertile days without veterinary testing is unreliable. Treat the entire 3–4 week heat period as potentially fertile for safety.
My dog in heat keeps trying to escape — what do I do? This is a strong hormonal drive and should not be underestimated. Double-check all fencing, always use a lead outdoors, and never leave her unsupervised in the garden. This behaviour stops when the heat cycle ends.
Can I walk my dog when she is in heat? Yes — exercise is beneficial and helps manage restlessness. Always keep her on a lead and avoid areas where intact male dogs are present. Choose quieter walking times and routes during her heat period.
How many times a year will my dog come into heat? Most medium-sized breeds cycle twice per year, approximately every 6 months. Smaller breeds may cycle more frequently; giant breeds less so. Individual variation is normal.
Also read: Dog Anxiety — Signs, Causes and Treatments | Enrichment Toys for Dogs | Separation Anxiety in Dogs | How Much Should I Feed My Dog
