What do you do when your dog gets her period?

When your dog gets her period (commonly called being “in heat”), it can trigger worry, practical questions and urgent decisions. This article walks through what to do now, why the cycle happens, how to spot trouble, and sensible steps you can take to keep your dog safe and comfortable.

Why your dog’s heat cycle matters — for her health and your household

Seeing blood on the bedding or sudden shifts in your dog’s behavior often feels alarming. I typically see owners who are worried about accidental pregnancy, embarrassed about household mess, or unsure whether the signs mean something more serious. Emotionally, owners can feel stressed, protective or out of control; dogs may feel restless, attract persistent male dogs, or change appetite and sleep. Clear, practical guidance helps reduce that stress and prevents outcomes—like unwanted litters or infections—that complicate life for both of you.

Practical concerns are common: keeping the house clean, avoiding mating, managing walks and social time, and deciding whether to spay. Immediate action is usually needed if there is heavy bleeding, a male dog is trying to mate, or the dog shows signs of systemic illness such as fever, vomiting or collapse. Those situations benefit from prompt containment and a veterinary phone call.

Right now: immediate steps to take when she starts bleeding

• Keep your dog indoors or securely leashed; prevent mating at all costs. Even a brief mating can lead to pregnancy.
• Contain mess with dog diapers or washable pads and protect furniture and bedding. Limit unsupervised access to other dogs.
• Watch for warning signs—heavy bleeding, foul smell, pale gums, lethargy—and call your veterinarian if you see them.
• If you are unsure about spaying, note that a discussion with your vet can cover timing, benefits (reduced risk of certain infections and tumors) and risks for your breed and age.

What’s happening biologically during a dog’s period (explained simply)

Dogs don’t menstruate like humans; their cycle is called the estrous cycle and has four main stages. Proestrus is the early phase when the vulva swells and a bloody discharge appears; females usually do not accept males yet. Estrus follows; this is when the female may stand to be mounted and is most likely to become pregnant. Diestrus is the period after estrus when progesterone levels remain elevated whether or not pregnancy occurred, and anestrus is the resting phase.

Hormones drive these stages. Estrogen rises during proestrus and makes the dog attractive to males while causing vulvar swelling and bloody discharge. As estrogen falls and luteinizing hormone spikes, ovulation occurs and progesterone rises around estrus, creating the fertile window. The bleeding you see is from blood-tinged discharge linked to changes in the uterus and vulvar tissues, not a shedding of the uterine lining as in humans.

Behavior can change noticeably: increased scent-marking, more attention-seeking or hiding, frequent licking of the vulva, and a tendency to attract persistent male dogs nearby. I often advise owners to expect some combination of these signs and to treat the timing as variable—each dog’s cycle can look a little different.

Timing and patterns: when her first and regular cycles typically begin

First heats most commonly occur between about six and twelve months of age in many small to medium-breed dogs, and they often happen later—sometimes up to 18–24 months—in many large or giant breeds. After the first cycle, many dogs cycle roughly every six months, but there is real variability: some dogs cycle three times a year, others once a year.

Breed and size matter: smaller breeds tend to reach puberty earlier and may have shorter cycles, while larger breeds may have longer intervals between heats. Seasonal or environmental influences may be less pronounced in companion dogs living indoors than in free-roaming or feral populations, but some owners notice a tendency for cycles to cluster by season in certain breeds.

Know the risks: warning signs that require veterinary attention

Most heats are uncomplicated, but several signs should prompt immediate veterinary attention. Excessive bleeding—so much that it soaks through pads or bedding—or blood that’s bright red and continuous is not normal. A foul-smelling discharge, fever, loss of appetite, vomiting, rapid breathing, or pale gums may suggest infection or blood loss.

Pyometra, a dangerous uterine infection, can develop in the weeks to months after estrus and often presents with thick, sometimes foul discharge, lethargy, increased thirst and a swollen abdomen. If your dog suddenly becomes very quiet, refuses food, or you notice swelling and discharge from the vulva with systemic signs, seek emergency veterinary care. Also treat aggressive mating attempts or injuries from over-zealous males as urgent: bites, torn skin and stress-related injuries can occur.

A practical owner checklist: what to do, day by day

When you first spot blood: calmly move your dog to a safe indoor area, keep her confined to a room that’s easy to clean, and put on a dog diaper or lay down washable pads. Avoid crating for long periods if your dog is restless; instead provide a quiet, supervised rest area. Change bedding and diaper frequently and wash hands after cleaning.

For outings, always use a secure, fixed-length leash and a well-fitting harness. Take short, direct walks in low-traffic areas to reduce encounters with male dogs. Never allow off-leash time in parks or dog runs; one moment of inattention can result in mating. If a male dog approaches, step between them, call your dog back, and move away together. If an encounter looks like it might escalate, pick up your dog if she is small and safe to lift, or retreat to your car or home.

Monitor the cycle by noting the first day of bleeding and tracking behavior daily. Typical proestrus lasts roughly a week, followed by estrus for several days, but timing can vary—recording dates will help you anticipate the next cycle. If you do not intend to breed, discuss spaying with your veterinarian; the timing of surgery and health considerations depend on your dog’s age, breed and medical history. If pregnancy is a concern after an accidental mating, contact your vet quickly to discuss options and possible diagnostics.

Adjusting home life, walks and training while she’s in heat

Change routines to reduce stress and the chance of mating. Walk at quieter times, use routes with fewer off-leash dogs, and bring high-value treats to reinforce recall and attention. I often recommend practicing a strong emergency recall cue during non-heat periods so it’s reliable when you need it. Teach and reward “leave it” and “come” in distraction-rich environments, starting with short, controlled sessions.

At home, limit access to front doors or yards where males can congregate near your property. Provide enrichment—chew toys, puzzle feeders, scent games—to keep attention directed away from the stress of surrounding males. If you live with another intact male dog, supervise interactions closely or separate the dogs during the heat to avoid forced matings and injury.

Helpful gear: pads, doggy diapers and other supplies that make life easier

• Dog diapers (reusable or disposable) sized for a snug fit; washable belly bands for males if needed. Use breathable materials and change often to prevent skin irritation.
• Washable pads or puppy training pads for bedding and furniture; mattress protectors for crates and sofas; designate a washable blanket for the dog’s resting spot.
• Sturdy harnesses and fixed-length leashes (3–6 ft) to maintain control. Consider a car crate or a crash-tested car harness for safe travel. Also keep enzymatic cleaners and odor-neutralizing solutions for accidents.

Spaying or breeding? Key questions and timing to consider

If you’re thinking about spaying, talk with your veterinarian about timing and breed-specific recommendations. Spaying before the first heat may reduce the risk of mammary tumors and eliminates the risk of pyometra; however, timing can be adjusted for young large-breed dogs to consider growth plate and orthopedic health. I usually recommend a tailored discussion that weighs your dog’s breed, age, and lifestyle.

If you intend to breed, work with a veterinarian or a reputable breeder to plan health screening, timing of mating and prenatal care. Breeding responsibly includes screening for genetic diseases, ensuring vaccinations and parasite control are current, and having a plan for whelping and puppy placement.

Final tips and reminders to keep you calm and prepared

A few small habits make a big difference: keep a calendar of cycle dates, prepare a “heat kit” with diapers, pads and cleaners ahead of time, and practice leash and recall skills regularly. If you notice anything unexpected—persistent bleeding, discharge with odor, fever, extreme behavioral change, or suspected mating—call your veterinarian promptly. With calm management and a sensible plan, most heats pass without major problems and your dog can stay safe and comfortable.

Sources, vet guidance and further reading

• Merck Veterinary Manual: “Canine Estrous Cycle” and “Pyometra in Dogs” (Merck Vet Manual Online, sections on reproductive disorders)
• American Veterinary Medical Association (AVMA): “Spaying and Neutering” guidance and resources on reproductive decisions
• American Kennel Club (AKC): “How to Tell When Your Dog Is in Heat” and practical owner advice
• Johnston SD, Root Kustritz MV, Olson P. Canine and Feline Theriogenology. 2nd ed. (Textbook covering reproductive physiology and clinical management)
• Spain CV, Scarlett JM, Houpt KA. “Long-term risks and benefits of spay-neuter in dogs” J Am Vet Med Assoc. 2004;224(10):1542–1551 (discussion of population-level outcomes and health considerations)