Dog Heat Cycle Calculator — Track Your Dog's Estrus Cycle
Predict when your female dog will go into heat, understand all four stages of the estrous cycle, and know exactly when she's fertile. Used by 50,000+ dog owners.
Understanding your dog's heat cycle helps you plan and care for her properly
Quick Answer:
Dogs typically go into heat every 6 months, with each cycle lasting 2-4 weeks. The fertile period (estrus) is usually days 10-14 when she'll accept males. Signs include swollen vulva, bloody discharge, and behavior changes.
Predict Next Heat Cycle
The 4 Stages of the Dog Heat Cycle
Proestrus
(7-10 days)Physical Signs
- * Swollen vulva
- * Bloody discharge
- * Frequent urination
- * Tail tucking
Behavior Changes
- * Attracts males but rejects them
- * May seem more clingy
- * Licking genital area
- * Changes in appetite
Estrus (Standing Heat)
(5-14 days)Physical Signs
- * Discharge lightens (pink/straw colored)
- * Vulva softens
- * Flagging tail
- * Standing for males
Behavior Changes
- * Receptive to males
- * May try to escape
- * Presents hindquarters
- * More affectionate
Diestrus
(60-90 days)Physical Signs
- * Discharge stops
- * Vulva returns to normal
- * Hormones stabilize
- * No attraction to males
Behavior Changes
- * Returns to normal
- * May show nesting (false pregnancy)
- * Appetite normalizes
- * Energy returns
Anestrus
(3-4 months)Physical Signs
- * No visible signs
- * Normal vulva
- * Normal behavior
- * Resting phase
Behavior Changes
- * Completely normal
- * No interest from males
- * Regular eating habits
- * Normal activity
Caring for a Dog in Heat
Do's
- * Keep her away from intact males
- * Use doggy diapers to manage discharge
- * Keep her on leash during walks
- * Maintain normal routine as much as possible
- * Provide extra comfort and attention
- * Keep her clean with gentle wiping
Don'ts
- * Don't leave her unsupervised outside
- * Don't take her to dog parks
- * Don't board her with other dogs
- * Don't assume she's safe just because she rejects males early on
- * Don't scold her for messes - it's natural
Frequently Asked Questions
How often do dogs go into heat?▼
Most dogs go into heat every 6 months (twice a year). However, this varies by breed and individual. Small breeds may cycle every 4 months, while giant breeds may only cycle once a year. Young dogs may have irregular cycles until they mature.
How long does a dog stay in heat?▼
A dog's heat cycle lasts 2-4 weeks total. The fertile period (estrus) lasts 5-14 days within this cycle. The entire reproductive cycle, including the resting phase, spans about 6 months before the next heat begins.
What are the signs a dog is going into heat?▼
Early signs include: swollen vulva, bloody vaginal discharge, increased urination, behavior changes (clingy or restless), licking genital area, and males showing interest. These signs appear in the proestrus stage, about 7-10 days before the fertile period.
When is a dog most fertile during heat?▼
Dogs are most fertile during estrus (standing heat), typically days 10-14 of the cycle. Signs she's fertile: discharge becomes lighter/straw-colored, she 'flags' her tail to the side, and she'll stand still when approached by a male. Ovulation usually occurs 2-3 days into estrus.
At what age do dogs first go into heat?▼
Small breeds typically have their first heat at 6-9 months old. Medium breeds at 9-12 months. Large and giant breeds may not have their first heat until 12-24 months old. Early spaying is recommended if you don't plan to breed.
Understanding Your Dog's Heat Cycle: A Complete Guide
The canine estrous cycle — commonly called "going into heat" — is the reproductive cycle that unspayed female dogs experience. Understanding this cycle helps you protect your dog from unwanted pregnancy, manage her comfort, and make informed decisions about breeding or spaying.
When Can a Dog Get Pregnant?
A dog can get pregnant during the estrus (standing heat) phase, which typically lasts 5-14 days and usually begins around day 10 of the heat cycle. This is when ovulation occurs and she'll actively accept male dogs. However, sperm can survive in the reproductive tract for up to 5 days, so the actual window of risk extends beyond just the fertile days.
It's a common myth that dogs can't get pregnant during their first heat — they absolutely can. If you're not planning to breed, keep your dog away from intact males during the entire 2-4 week cycle. Learn more in our guide on when dogs can get pregnant.
Heat Cycle Variations by Breed Size
| Dog Size | First Heat | Cycle Frequency | Example Breeds |
|---|---|---|---|
| Small (under 20 lbs) | 6-9 months | Every 4-6 months | Chihuahua, Yorkie, Maltese |
| Medium (20-50 lbs) | 9-12 months | Every 6 months | Beagle, Cocker Spaniel, Bulldog |
| Large (50-80 lbs) | 12-18 months | Every 6-8 months | Golden Retriever, Lab, GSD |
| Giant (80+ lbs) | 18-24 months | Every 8-12 months | Great Dane, Saint Bernard |
Grooming During Heat
Dogs in heat need extra grooming attention. Keep the genital area clean by gently wiping with unscented pet wipes. Some owners use dog diapers to manage discharge — if you do, change them frequently to prevent irritation. A sanitary trim (trimming the fur around the vulva) can help keep things cleaner. Many professional groomers offer sanitary trims as an add-on service.
Find groomers near you who can help with sanitary trims and maintenance during heat cycles. If you're curious about grooming costs, see our complete dog grooming cost guide.
Spaying: When and Why
Spaying (ovariohysterectomy) permanently prevents heat cycles and pregnancy. Most vets recommend spaying at 6-12 months of age, though the optimal timing varies by breed. Benefits include eliminating the risk of pyometra (a life-threatening uterine infection), reducing mammary cancer risk, and preventing unwanted litters.
If your dog is already pregnant, our dog pregnancy calculator can help you track her 63-day gestation and prepare for puppies. For information on pregnancy stages, read our dog pregnancy stages guide.
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Keep Your Dog Clean & Comfortable
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