Canine Heat Cycle
The canine heat cycle—sometimes labelled as the oestrus cycle or simply “season”—is the natural reproductive rhythm in female dogs. It’s the body’s way of signalling that a dog is biologically ready to breed, but it’s far more than just a matter of timing. For breeders and pet owners alike, grasping the ebb and flow of this cycle is a vital piece of the puzzle when it comes to making responsible decisions.
The Four Stages of the Canine Heat Cycle
The canine heat cycle unfolds across four distinct phases, each carrying its own signs, shifts, and implications. Whether you’re gearing up to breed or just trying to dodge a surprise litter, knowing what happens in each stage makes all the difference.
1. Proestrus
This is the starting bell. Hormones begin to stir, and the body gets to work. You might spot swelling around the vulva or notice a pinkish discharge. Behaviour also takes a turn—your dog might stick closer to you, act more distracted, or growl off male dogs who come sniffing around. She’s not ready to mate just yet, but her body is clearly getting into gear. Proestrus lasts about 7 to 10 days.
2. Estrus
This is the window when breeding can occur. The discharge usually darkens or tapers off, and the female may start standing still for males—a clear sign she’s receptive. Hormones peak, and ovulation takes place. If you’re planning a litter, this is the phase that needs your full attention. Many breeders lean on progesterone tests or cytology smears during this time to nail the right moment. Estrus lasts for 5 to 9 days.
3. Diestrus
The fireworks fade. Whether or not a mating has taken place, hormone levels shift and the female moves into a more settled stage. She’ll stop being receptive to males, and any discharge will likely clear up. If she’s pregnant, this is when the embryo implants and develops. If not, it’s simply her body winding down. Diestrus lasts about 60 days.
4. Anestrus
This is the off-season—the quiet period between cycles. Her body recovers, hormones stabilise, and there’s little to no visible activity. It’s a good time for health check-ups, dietary adjustments, or training that might have taken a back seat during the hormonal rollercoaster. Anestrus lasts 4 to 5 months in average dogs.
Most female dogs will experience their first cycle anywhere between six and sixteen months of age, depending largely on their breed and size. Smaller breeds often kick off their cycles sooner, while larger dogs may wait a little longer to get going. Once that first cycle begins, it tends to roll around every six to eight months, though again, some dogs might run on a slightly different internal clock.
The key here isn’t just knowing when a cycle starts—it’s knowing how each phase shapes your dog’s behaviour, body, and needs. Whether you’re thinking of breeding or simply want to keep your dog safe and healthy, understanding this cycle gives you a leg up in making smarter, more compassionate choices.
Signs a Dog Is in Heat
Spotting the signs of a dog in heat doesn’t take a microscope, but it does require a bit of attention. Each dog marches to the beat of her own drum, but most females follow a pattern you can spot once you know what to watch for.
Physical Clues
You’ll likely notice swelling around the vulva—that’s often the first tip-off that her cycle is kicking off. A bloody or straw-coloured discharge usually follows. Some dogs keep themselves squeaky clean, while others leave a little trail behind on floors or bedding. You might also catch her licking more than usual to stay tidy.
Her scent also changes. It’s not something you’ll pick up, but male dogs sure will. Even from a block away, they’ll catch wind and start making their presence known.
Behavioural Shifts
Hormones don’t just affect the body—they stir up behaviour too. Your dog might turn clingy or extra affectionate, shadowing you around the house. Some get testy or seem distracted, while others go full diva, striking flirty poses and lifting their tail when approached by male dogs.
A sudden interest in escaping the yard can also be a red flag. Dogs in heat have been known to scale fences, slip collars, or plot Houdini-level escapes just to find a mate.
What Breeders Should Know
If you’re breeding dogs—or even considering it—skipping over the finer points of the canine heat cycle is like baking without checking the oven temp. Timing matters, preparation counts, and doing things right makes all the difference.
Spotting the Right Moment
For those planning to mate their dog, Estrus is the narrow window you need to hit. This fertile stretch may last less than a week, so breeders often lean on tools like progesterone testing or cytology swabs to zero in on the best days. Guesswork won’t cut it here—if you miss the mark, you could miss the season.
Sidestepping Accidents
If breeding isn’t the plan, things can get dicey fast. Female dogs in heat give off a scent that can whip nearby males into a frenzy. Unplanned litters often happen because someone underestimated how determined an intact male can be. Avoid dog parks, tighten your fencing, and be vigilant—because one slip-up is all it takes.
Breeding With Intention
Responsible breeders don’t chase numbers. They wait until their dog is physically and emotionally mature—often around two years old—and they space out litters to allow proper recovery. They health test both parents, research pedigrees, and plan pairings with care, aiming to better the breed, not just grow their count.
This sort of commitment takes patience, time, and support, which is exactly where RPBA steps in.
Understanding the canine heat cycle isn’t trivia—it’s foundational. It affects health, timing, litter planning, and long-term welfare. Whether you’re managing your pet’s first season or fine-tuning your breeding program, knowing the phases and their impact puts you in the driver’s seat.
At RPBA, we don’t just promote responsible breeding—we help you live it. Gain access to tools, templates, and support designed to help you raise the bar with every litter by becoming a member today.
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