Dog Heat Cycle: Stages, Signs, Length and Care

By Tailwisp Editorial TeamUpdated October 17, 20263 min read

The heat cycle can surprise first-time owners, and a bit of preparation makes it easier.

When it starts

Most dogs have their first heat between about six and twelve months of age, with small breeds often earlier and giant breeds as late as 18 to 24 months. After that, cycles usually come about every six months, though some breeds, such as the Basenji, cycle once a year.

The four stages

1. Proestrus, about 7 to 10 days: vulva swells, bloody discharge begins, males are attracted but she usually refuses them.
2. Estrus, about 5 to 10 days: discharge often becomes lighter or straw-colored, she is receptive and fertile.
3. Diestrus, about 60 to 90 days: hormone levels change, she is no longer receptive, and pregnancy or false pregnancy can occur. See false pregnancy in dogs.
4. Anestrus: the resting phase before the next cycle.

Timing varies between dogs.

Signs of heat

• Swollen vulva
• Bloody or straw-colored discharge
• Frequent urination and marking
• Excessive licking of the area
• Restlessness or clinginess
• Flagging, moving her tail aside
• Attracting male dogs
• Mood and appetite changes

Preventing pregnancy

• Supervise closely, including in the yard
• Leash walks only, away from unneutered males
• Avoid dog parks, daycare and boarding
• Keep her inside when you cannot supervise
• Consider spaying after the heat or according to your vet's advice. See spay and neuter pros and cons

Dogs can conceive even when she appears to refuse males, and males can detect heat from a long distance.

Managing the mess

Use washable dog pants or diapers, towels on furniture and regular cleaning. Provide a crate or tiled room. Frequent short, gentle wipes keep her comfortable. See how to bathe a dog at home.

Behavior during heat

Some dogs become irritable, clingy or anxious, others more wandering. Provide extra exercise and mental activity. See dog behavior during heat.

Health and heat

• Pyometra is a serious uterine infection that can occur weeks after a heat. See pyometra in dogs
• False pregnancy is common after heat. See false pregnancy in dogs
• Excessive bleeding or a heat lasting beyond a month needs a vet check

Breeding and heat

Responsible breeders time breeding with progesterone testing and veterinary advice. See dog pregnancy signs and dog whelping guide.

Heat and spaying

Spaying during heat carries higher bleeding risk, so vets often wait until after the cycle. Ask your vet about timing. See dog spay recovery.

When to call your vet

Call if she has a foul-smelling discharge, lethargy, increased thirst, vomiting, fever or a swollen belly after her heat, or if the heat is abnormally long or heavy.

Questions to ask your vet

Ask when to expect the next heat, how to prevent accidental mating, whether spaying makes sense and what signs of pyometra to watch. Ask about timing for your breed.

Common mistakes

• Leaving her alone in the yard
• Assuming she is safe after the bleeding stops
• Skipping leashes
• Ignoring signs of infection

Troubleshooting

• My dog is bleeding for over a month: book an exam.
• Males keep appearing: keep her indoors.
• She seems unwell after her heat: call your vet.

A simple plan

1. Learn the stages.
2. Supervise closely.
3. Manage the mess.
4. Plan spaying or breeding with your vet.

Real-life examples

A spaniel's first heat is managed with diapers and leash walks. A terrier becomes pregnant after a brief unsupervised yard visit. A retriever develops pyometra weeks after a heat. Preparation helps.

Be prepared

A calm plan for the heat cycle makes life easier for everyone.

The takeaway

Heat lasts a few weeks every six months or so. Supervise carefully and talk to your vet about spaying.

This article is general educational information, not veterinary advice. Every dog is different. If your dog is unwell, or you are unsure about a symptom, diet change or medication, contact your veterinarian.