Dark Blood At End Of Dog Season

A pyometra is a bacterial infection in the uterus of a female dog. The condition occurs when there is bacterial invasion of the endometrium of the uterus. This usually occurs a few weeks after the dog has been ‘on heat’, but the time frame is variable relative to the heat cycle. When the uterus is exposed to high concentrations of hormones (estrogens and progesterone) without pregnancy, it can lead to a cystic lining of the uterus which provides an excellent environment for bacteria to colonise. The infection usually results from ascending bacteria through a partially open cervix during the ‘heat’ part of the dog’s cycle.

Pyometra most commonly occurs in females >6 years of age, however we have also seen the condition in younger dogs, and occasionally in very young female dogs. It is most commonly diagnosed 1-12 weeks following the dog being ‘on heat’. 1 in 4 undesexed female dogs will develop a pyometra during their lifespan.

Signs of a pyometra are generally that of a very unwell dog, such as lethargy, inappetance, vomiting, depression, and sometimes a visibly enlarged abdomen can be seen. A pyometra can be ‘open’ or ‘closed’. In an open pyometra the pus discharges out of the vagina – as seen by a yellow, green or red/brown copious discharge from the vulva of the dog. The diagnosis of an open pyometra is therefore easier if there is a visible discharge.

A closed pyometra is when the cervix is closed and there is no discharge. This can result in a severely distended uterus which is at risk of rupturing. Sometimes we use other diagnostic tests such as blood tests, ultrasound or x-ray to make the diagnosis of a pyometra.

In any case a pyometra is a serious life threatening condition in a female dog. It can rapidly lead to bacterial septicaemia and then death if left untreated. The treatment involves rapid intravenous fluid therapy and antibiotics, followed by surgery once the patient is stable for a general anaesthetic. The surgery required is an emergency ovario-hysterectomy (spey) to remove the uterus. Antibiotics alone are not successful in the treatment of a pyometra.

Pyometra is easily prevented by desexing your female dog, which we recommend doing at 4-6months of age.

Dog in heat dark brown blood

Your dog may have any color of the discharge. It may start off clear to pink, then turn red and eventually a dark brown. This is usually seen at the end of their cycle. If your dog continues producing dark brown to black color blood, it would be best for your vet to examine your dog.

Silent Heats

In this case, the heat is silent, meaning that there are hardly any outward signs to suggest that the heat has occurred.

Split Heat

In this case, the dogs heat is interrupted and then continued at a later time. Basically, a female dog will exhibit signs of proestrus (including the typical bleeding), but then once estrus approaches the symptoms disappear for some time.


This phase concludes the mating process, as most females at this point will no longer be interested in males. Males, however, may still stick around. This phase if the dog has been impregnated lasts generally from the end of the estrus until the birth of the puppies, averaging therefore 60 days. If the dog has not been impregnated, the diestrus phase will not be any different from the anaestrus stage.


What color should my dogs period blood be?

Question: My female dog discharged dark red blood once or twice a day after mating. Does this mean she is not pregnant? Answer: It is normal for a dog in heat to continue to have some bleeding even after they’ve been bred.

Do dogs bleed at the end of their heat?

At first, the discharge is very bloody, but as the days pass, it thins to become watery and pinkish-red in color. A female dog that is in heat will often urinate more frequently than normal, or may develop marking behavior, in which she urinates small amounts on various objects either in the home or when out on a walk.

Why is my dog bleeding brown blood?

You may also observe that her vulva is large, red, or swollen with some bleeding or blood-tinted discharge. Your dog will only bleed for around half of the total cycle, usually 7 to 10 days. Generally, bigger dogs bleed more than smaller dogs, but it varies between dogs. Some dogs bleed very little.