Ovarian remnant syndrome - Why a spayed dog might appear to be in season

Ovarian remnant syndrome - Why a spayed dog might appear to be in season

Health & Safety

The vast majority of female dogs within the UK are spayed, in order to reduce unwanted pregnancies and avoid contributing to the surplus of dogs without homes all over the UK. The actual spay operation itself, while a major surgery, is relatively straightforward, and most vets perform hundreds of spay procedures every year without incident. However, in some rare cases, owners of spayed bitches may run into problems some time after spaying, and find that their bitch begins behaving as if she is in heat, when she is not.

This behaviour is of course undesirable and unusual, and may manifest in a variety of different ways. If your bitch seems to behave as if she is in heat at times when this is not possible, read on to learn more about the potential reasons behind it.

In what ways might this behaviour manifest itself?

A bitch having a false season or behaving as if they are in season might display a range of both physical and behavioural changes. Behavioural changes might include nesting behaviour, overt sexual displays, becoming clingy, going off her food, appearing bad tempered and seeking out un-neutered male dogs. These changes are usually psychological rather than physical.

In some cases, the bitch will also display physical indicators that she is genuinely in season, such as a swollen vulva and even bleeding. If this is the case, it is important to verify with your vet that your bitch was actually genuinely spayed; and that there was not a mix-up in the practice, or possibly, if you took on an adult bitch and was told that she was spayed, that this was the truth.

Behavioural reasons

If your dog displays behavioural but not physical indications of being in season, it is important to keep a track of when they occur. If your bitch’s behaviour changes for just two to three weeks at a time, this is likely to be a false season, but if she behaves in that way for the vast majority of the time, it is likely a behavioural issue in general, which may require the help of a behaviourist to correct.

If a bitch was spayed after around two years old and particularly if she had already had at least one litter, she might display nesting behaviour at times, which can be accompanied by the signs of being in season. Again, this behavioural problem can be corrected, but you will probably need professional help.

Ovarian remnant syndrome

If your bitch’s false or seemingly impossible season comes accompanied by the physical symptoms outlined earlier on, it is possible that your dog has ovarian remnant syndrome.

The spaying procedure works by removing the ovaries in their entirety, so that there are no eggs left to form and be released, which triggers the season and readiness to breed. However, in some rare cases, a tiny amount of the ovarian tissue from one or both ovaries might not be fully removed, remaining intact within the bitch’s body after the operation has been completed.

Even a very small particle of ovarian tissue can be sufficient to trigger the hormonal changes that bring a bitch into season, causing them to behave to all intents and purposes as if they are an unspayed bitch that is ready to breed. This is what is known as ovarian remnant syndrome.

While bitches with ovarian remnant syndrome are not capable of breeding, and cannot conceive and carry a litter even if they mate, the condition can of course be problematic, and should be corrected.


If your bitch is displaying the physical signs of ovarian remnant syndrome and both you and your vet are confident that she has in fact been spayed- perhaps by shaving the stomach fur to see the surgical scar, or performing exploratory tests such as an ultrasound examination- the next step is to test for ovarian remnant syndrome.

This means that ovarian remnant syndrome must be positively diagnosed, usually by means of an exploratory laparotomy or ex-lap, which involves placing the bitch under general anaesthetic, and making an incision into the abdomen to get inside and investigate what is really going on!

If remnant ovarian tissue is indeed found as part of the procedure, the small amount of tissue causing the problem will usually be removed as part of the same operation.

While surgical exploration and treatment is generally thought to be the best way of dealing with ovarian remnant syndrome, it is not the only way. For some bitches, surgery is not an option, possibly due to their age or general health, and in this case the condition can be managed by means of medication. However, the medication is only effective for as long as it is taken, and so the bitch will need to remain on medication to present future false seasons for the rest of her life.



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