Heat in Dogs (Estrus Cycle in Female Dogs)
Is your female dog acting odd, leaving spots, or attracting new suitors? She may be in heat, also called the estrus cycle. At sexual maturity, a bitch can become pregnant, sometimes sooner than you expect.
This guide explains the estrus cycle, the signs to watch for, and simple ways to keep your home tidy. You will also learn how to keep her safe and calm. By the end, you will feel ready for her next heat cycle.
Key Takeaways
- Female dogs usually go into heat twice a year, each cycle lasts two to four weeks, and bleeding often lasts about 7 to 10 days.
- Typical signs include a swollen vulva, changing vaginal discharge, mood shifts, frequent urination, and attention from male dogs.
- Spaying during anoestrus lowers the risk of pyometra, mammary tumours, and other uterine disease, and can extend lifespan by about 26 percent.
- Large and giant breeds often have fewer cycles than toy or small breeds; first heat may start at 5 months, but most reach peak fertility around 12 to 15 months.
- Unspayed bitches can develop false pregnancy, pyometra, or certain cancers, and unexpected litters happen easily without close supervision.
Understanding the Estrus Cycle in Female Dogs
The oestrus cycle, also called the estrus cycle, is your bitch’s natural breeding rhythm. Hormones shift across the cycle and drive changes in behaviour. The ovaries release eggs during ovulation, which makes her receptive to breeding.
What is the estrus cycle?
A bitch is “in heat” during her fertile phase of the cycle. Some start as early as five months, but most are better suited to breed at 12 to 15 months. Unlike human menstruation, bleeding here signals the start of heat, not the end of ovulation.
The cycle has four stages: proestrus, oestrus, diestrus, and anoestrus. Oestrogen and progesterone are the main hormones. They shape mood, appetite, and mating interest. Mounting and restless pacing can appear during these hormone surges.
Most dogs cycle about every six to seven months. As one vet likes to say:
Dogs have no menopause, they keep cycling for life.
The four stages: Proestrus, Estrus, Diestrus, Anestrus
Each stage affects behaviour, fertility, and care needs. Here is a simple breakdown.
- Proestrus starts the heat. It averages 9 days, but 3 to 17 days is possible. The vulva swells and a bloody discharge begins. Oestrogen rises. She may flirt, but most bitches do not accept mating yet.
- Estrus follows, lasting 3 to 21 days. This is the fertile window. Progesterone rises as oestrogen falls. Discharge turns pink or straw coloured. She becomes receptive to males and may stand for mating while ovulating.
- Diestrus ends fertility and runs for about 2 to 3 months. The vulva returns to normal. Progesterone stays high for a time. If she was bred, this is when pregnancy develops.
- Anestrus is the resting stage, often 100 to 150 days. Hormones settle, and the uterus resets before the next cycle.
- Proestrus and estrus together make up the “in heat” period. That phase typically lasts two to four weeks. Bleeding is usually seen for about seven to ten days, often lighter at the start and end.
- Giant breeds like Great Danes may have fewer yearly cycles than terriers or toy breeds. Many large dogs cycle two, sometimes three, times per year.
- Frequent urination is common in proestrus and estrus. Hormones can also change appetite, sleep, and barking. Some try to roam to find mates.
- Vets may use vaginal cytology, a simple swab test, to identify the current stage. This helps plan breeding or decide on spay timing.
- Health risks exist in intact bitches, including pyometra and mammary tumours. Early spay, called an ovariohysterectomy, reduces these risks.
- Missing subtle signs, like mild swelling, can confuse owners. This is true for any breed, from a German Shepherd to a spaniel. When unsure, ask your vet.
Signs of a Dog in Heat
Many bitches act a little off during heat. You may notice mood swings, clingy behaviour, or a sudden interest in roaming. Physical signs from the reproductive tract help confirm what is happening.
Behavioural changes
Mounting can start early. She may mount other dogs, cushions, or a leg. Many bitches become friendlier with male dogs and ignore familiar cues. The goal shifts to finding a mate, not listening to you.
Anxiety can spike. Some shadow you from room to room or stash toys like they are setting up a nest. Appetite may wobble. Urine marking spreads pheromones, which attract local males like a magnet.
Some girls “flag” by moving the tail aside near a male. Others guard their rear from curious noses.
My little Rosie gathered socks and slippers before every season, her own odd nesting ritual, says Julie from Dogs Trust.
Next, look for the physical symptoms that confirm she is in estrus.
Physical symptoms
One early sign is a swollen, reddened vulva. A bloody discharge usually appears in proestrus, then turns watery and lighter in colour. It may look pink, yellowish, or brown as days pass.
Most bitches lick their genitals more because of the swelling and discharge. Urination often increases, which creates dog hygiene issues indoors. Bleeding commonly lasts 7 to 10 days, though some spot for a bit longer. Discomfort is common, pain is less so.
As the cycle advances, discharge becomes lighter. Some females get agitated or snappy. Think cranky teen meets muddy winger after extra time.
Duration and Frequency of Heat Cycles
Puberty timing varies between breeds and even littermates. The first heat cycle can catch new owners off guard. It often lasts long enough to feel never ending.
How long does a heat cycle last?
A typical heat cycle runs about three weeks, with a normal range of two to four weeks. Bleeding usually shows for seven to ten days. Some girls spot for eight to thirteen days, lighter at the start and end.
Proestrus can last 3 to 17 days. Estrus may last 3 to 21 days. These stages together are the fertile period if she ovulates. Diestrus then runs for two to three months. Anoestrus follows, resting the body for 100 to 150 days before the next cycle.
As Dr Ryder at PetVet Clinic says, dogs do not keep calendars, but their bodies do.
How often do dogs go into heat?
Most bitches cycle about every 6 to 7 months after the first season. That gives two heat cycles per year for many breeds. Small breeds, like Chihuahuas, can start earlier and may cycle more often. Giant breeds, like Great Danes, may wait over a year for the first season.
Older bitches often cycle less often with age, yet pregnancy is still possible. Each dog is different. Breed, size, and health history all matter. Unless spayed, a female dog will continue to have seasons for most of her life.
Managing a Dog in Heat
Housekeeping and comfort make this phase easier. A calm space, soft bedding, and a steady routine help her relax. Gentle cleaning keeps smells down and supports good dog hygiene.
Hygiene and cleanliness
Heat can be messy for a couple of weeks. These steps reduce cleaning and keep your girl comfortable.
- Use dog period pants to catch blood spots. They do not prevent mating or stop male interest.
- Introduce period pants before heat starts so she gets used to wearing them.
- Cover sofas, beds, and chairs with towels or old sheets to protect fabric.
- Limit access to carpeted rooms. Hard floors are easier to clean if accidents happen.
- Most bitches self-groom. Spot clean with warm damp cloths or pet-safe wipes if needed.
- Use a fresh cloth each time, then pat dry for comfort. This helps prevent infection.
- Bleeding varies by dog. Some need more frequent freshening up.
- Dog nappies or restricting her to one easy-clean area can cut down the laundry pile.
- Use bleach-free cleaners for urine or blood marks to protect sensitive noses and paws.
- Clean spills quickly by hand on wood or tile to prevent stains.
Keeping things tidy protects surfaces and helps her feel settled.
Providing comfort and care
Offer a quiet corner with cosy bedding and extra affection. Many bitches want to cuddle. Others prefer space. Follow her lead.
Use food puzzles to burn mental energy indoors. Keep walks short and away from areas with off-lead males. Expect more toilet breaks due to frequent urination. Have quick access outside or use puppy pads inside.
Appetite may rise or fall across the cycle. Adjust portions as needed. Keep play gentle if she seems sore or irritable.
A bit of kindness can make a cloudy day easier for both of you.
Preventing Pregnancy During Heat
Preventing an unwanted litter takes planning. Supervision is your first defence. Spaying, done at the right time, provides long term protection against pregnancy and several diseases.
Supervision and isolation
Walk a bitch in heat at quiet times and keep her on a lead. Pick calm routes to avoid unneutered males. At home, check gates and fences because determined males get creative.
Supervise garden time, even for a quick loo break. Sperm can survive for days inside a bitch. If you have an entire male at home, use solid doors, not baby gates. If an accidental mating occurs, call your vet within 72 hours to discuss options.
Spaying and its benefits
Spaying stops pregnancy and heat cycles. Vets often plan it during anoestrus, the resting phase. Timing can vary by breed and age, so ask your vet surgeon for advice.
Health benefits are significant. Spaying cuts the risk of mammary cancers and prevents uterine and ovarian disease, including pyometra, a life threatening womb infection. Studies suggest spayed bitches may live about 26 percent longer.
Behaviour often settles. Many stop urine marking, restless pacing, and loud calling. Shelters and rehoming centres also benefit, as fewer surprise puppies need homes. Surgery during heat is trickier and riskier, so most vets wait two to three months after bleeding stops.
Complications Related to Heat
Heat can lead to health problems or surprise puppies. Spotting issues early makes treatment safer and cheaper. When worried, speak to your vet promptly.
Common health risks
False pregnancy is common in intact bitches after a season. Hormones can make her act pregnant or even produce milk. This state can raise the chance of pyometra, a dangerous womb infection.
Warning signs include poor appetite, low energy, vomiting, drinking more, heavy licking of the vulva, smelly discharge, or bleeding that is heavier or lasts beyond ten days. These are urgent signs. Contact your vet straight away.
Unspayed bitches face higher risks of mammary gland tumours and cancers in the womb or ovaries. Diestrus hormone swings can also trigger stress or medical issues. Timely care lowers these dangers.
Unplanned pregnancies
Accidents happen. If a bitch mates while in heat, pregnancy can follow. Sperm can live for several days inside the reproductive tract. Responsible breeders wait until full maturity, usually after a few seasons, before planned mating.
If pregnancy occurs, your vet will advise on care. Pregnant bitches need balanced nutrition and measured exercise. Set up a clean whelping area before the due date. Arrange vet checks for mum and puppies after birth.
If you need help finding homes, groups like Dogs Trust or Blue Cross can support rehoming. Tests such as vaginal cytology and progesterone blood sampling can confirm timing and pregnancy status when litters are suspected.
Each dog handles heat differently, but small comforts make a big difference. Something as simple as a carrot dog toy plush can provide distraction and relief while you manage the cycle with care.
Conclusion
Heat in dogs can feel like a lot, for both of you. From mood swings to messy floors, the estrus cycle tests patience. With early spotting of signs, smart cleaning, and strict supervision, most homes cope well.
Spaying during anoestrus prevents pregnancy and lowers serious health risks, including pyometra and mammary cancers. If your female dog is in heat now, keep her on a lead, control access at home, and plan the next steps with your vet. This information is general guidance, not a substitute for veterinary advice.
Stay calm, stay consistent, and you will handle each heat cycle with confidence.
FAQs
1. What does it mean when a female dog is in heat, and can she fertilise during this time?
When a female dog is in heat, her body prepares to mate. She can fertilise if she mates with a male at the right moment in her cycle.
2. How long does the estrus cycle last for most dogs?
The whole process usually takes about three weeks from start to finish. During this window, your pet may be able to fertilise eggs if mating happens.
3. Are there signs that show my dog is ready to fertilise?
Yes, you might notice swelling or discharge and changes in behaviour like restlessness or seeking attention from males; these are clues she's ready to fertilise.
4. Can I prevent my dog from being able to fertilise while she's on heat?
You can keep her indoors and away from male dogs during this period; spaying before her first season also stops any chance of future cycles where she could fertilise eggs.