A dog that is still bleeding after four weeks has exceeded the normal duration of a heat cycle and likely needs veterinary attention. The bleeding phase of heat (proestrus) typically lasts six to eleven days, and the full heat cycle, including the stage where a dog is receptive to mating, usually wraps up within three weeks at most. Four weeks of continuous or recurring vaginal bleeding points to something beyond a routine cycle.
Several conditions can explain prolonged bleeding, ranging from a heat cycle that’s running long to serious infections. The cause depends partly on whether your dog is spayed or intact, and whether she recently had puppies.
A Prolonged Heat Cycle
If your intact (unspayed) dog started bleeding around four weeks ago and never seemed to stop, she may simply be experiencing an unusually long heat. The estrus stage alone can last anywhere from one to twenty days, according to Cornell University’s College of Veterinary Medicine, and when you add that to a proestrus phase on the longer end, some dogs can bleed or discharge for close to three weeks before things taper off. Four weeks pushes past that range, though, and warrants investigation.
One of the most common medical reasons for a heat that won’t end is follicular ovarian cysts. These develop when a follicle on the ovary fails to release an egg and instead keeps producing estrogen. That sustained estrogen keeps your dog’s body locked in a state that mimics heat: the vulva stays swollen, the bloody or pinkish discharge continues, and over time you may notice hair thinning along the neck, trunk, or rear end. A vet can check estrogen levels and use ultrasound to look for cysts on the ovaries.
Pyometra: A Uterine Infection
Pyometra is a bacterial infection of the uterus that typically develops in the weeks following a heat cycle. It’s one of the more dangerous possibilities when an intact dog keeps having discharge well past the expected timeline. The discharge can be cream-colored, bloody, or a mix of both, and it sometimes has a foul smell.
What makes pyometra especially concerning is that it can progress to a life-threatening situation quickly. Beyond the vaginal discharge, watch for these signs:
- Lethargy or unusual tiredness
- Loss of appetite
- Increased thirst and urination
- A swollen or painful belly
- Vomiting
- Fever
- Pale gums
- Weakness or collapse
In some cases, the cervix stays closed, meaning the infected fluid builds up inside the uterus with little or no visible discharge. These “closed” pyometras tend to cause more severe illness because the infection has no way to drain. If your dog is showing any combination of the symptoms above, even without heavy discharge, this is an emergency.
Bleeding After Having Puppies
If your dog gave birth roughly four weeks ago and is still bleeding, the most likely explanation is a condition called subinvolution of placental sites (SIPS). After a dog delivers puppies, the spots where each placenta attached to the uterine wall normally heal and shrink. In SIPS, that healing process stalls, and the sites continue to ooze blood.
SIPS is the leading cause of persistent bloody vaginal discharge after whelping. In many dogs it resolves on its own, but “on its own” can mean months. In one documented case, an untreated dog continued bleeding until roughly 120 days after giving birth. Another bled for even longer, not stopping until 270 days postpartum. The good news is that affected dogs are generally healthy otherwise, and effective treatment exists. A short course of oral medication can stop the discharge within about two weeks without affecting future fertility.
Bleeding in a Spayed Dog
If your dog has been spayed and is bleeding from the vulva four weeks later, the situation is different. Spayed dogs shouldn’t have heat cycles at all, so any vaginal bleeding is abnormal.
Possible causes after a spay include surgical complications like infection at the internal surgical site, which can produce redness, swelling, and discharge. If the spay was performed while your dog was in heat or very close to it, residual hormonal activity can briefly mimic a cycle. In rare cases, a small piece of ovarian tissue is left behind during surgery (ovarian remnant syndrome), and that tissue can produce enough hormones to trigger heat-like bleeding months or even years later.
Vaginal tumors or polyps are another possibility in spayed dogs, particularly older ones. The most common sign is a discharge from the vulva or a visible mass protruding from it. The majority of vaginal tumors in dogs are benign, typically arising from smooth muscle or fibrous tissue. In a large retrospective study, roughly 73% of vaginal tumors were benign, about 17% were malignant, and the remainder were transmissible venereal tumors. Even benign growths can cause persistent bleeding and discomfort, so they generally need to be removed.
Clotting Disorders
Less commonly, prolonged bleeding from the reproductive tract can stem from a problem with blood clotting itself rather than a problem with the reproductive organs. Von Willebrand disease is the most widespread inherited bleeding disorder in dogs. In its severe form, it causes spontaneous bleeding from the nose, mouth, urinary tract, reproductive tract, or intestines. If your dog has a history of bleeding excessively from minor wounds, bruising easily, or prolonged bleeding after any procedure, a clotting disorder may be compounding whatever else is going on. Certain breeds, including Doberman Pinschers, German Shepherds, and Golden Retrievers, carry higher risk.
What Your Vet Will Check
A vet evaluating a dog with four weeks of bleeding will typically start with a physical exam and a vaginal cytology, which involves looking at cells from the vaginal lining under a microscope. This can reveal whether your dog is still under the influence of estrogen (suggesting cysts or a prolonged heat), whether infection is present, or whether abnormal cells point to a growth. Blood work helps assess overall health, check for anemia from ongoing blood loss, and evaluate organ function. An abdominal ultrasound is often the most revealing test, as it can identify ovarian cysts, a fluid-filled uterus consistent with pyometra, retained placental tissue, or masses.
The specific combination of your dog’s reproductive status (intact, spayed, or recently postpartum), the color and consistency of the discharge, and her overall behavior will guide which of these possibilities the vet pursues first. Bright red, active bleeding is a different clinical picture than dark, foul-smelling discharge, and each points in a different diagnostic direction.