Spayed (Desexed) Cat in Heat

Why is my spayed cat calling?

When a cat is spayed (ovariohysterectomy), the ovaries, oviducts, and uterus are removed. The ovaries produce hormones that are responsible for the heat cycle in cats. Therefore when the cat is spayed, the heat cycle should stop. So how can a spayed cat come into heat?

In some cases, a small portion of the ovary is left behind and continues to produce hormones that trigger the heat cycle. When this occurs, she will continue to go into heat, but can not become pregnant. This is known as ovarian remnant syndrome (ORS).

Is the veterinarian at fault?

Not necessarily, some females may have additional ovarian tissue underneath the ovary, which can be easy to miss at the time of surgery.

Symptoms can occur days or years after surgery, there appears to be no breed predisposition.

  • Calling (loudly)
  • Being extra affectionate
  • Restlessness
  • Rolling
  • Lordosis in which the cat lowers her front half and raises the rear

A cat will mate at this time if given the chance. Although she will not be able to fall pregnant, she is at risk of infectious disease, in particular, feline leukemia virus.


  • Vaginal smear, a sample of cells from the vaginal wall is examined under a microscope. This must be performed at the time of estrus and a positive result will show the presence of cornified vaginal epithelial cells.
  • Testing for elevated estrogen and progesterone levels in blood serum.
  • Ultrasound may reveal the presence of ovarian tissue, however, this may not always be visible on ultrasound.


Surgical exploration to locate and remove the ovarian tissue will be carried out when the cat is in heat when the tissue is more visible.


  • Julia Wilson, 'Cat World' Founder

    Julia Wilson is the founder of Cat-World, and has researched and written over 1,000 articles about cats. She is a cat expert with over 20 years of experience writing about a wide range of cat topics, with a special interest in cat health, welfare and preventative care. Julia lives in Sydney with her family, four cats and two dogs. Full author bio

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