As bizarre as this may sound…it can and does occasionally happen! If someone had told me that it was possible, I would have looked at them like they were crazy… until it happened to our Lilly.
We adopted, Lilly, from a local Rescue Group at which point Lilly had not yet been spayed due to age. We were given a voucher to have her spay done at a local vet clinic. After booking her spay, Miss Lilly was taken in and not happy about it at all…she hated to ride in the car and was not fond of the vet. Little did we know that this traumatic experience would get even worse.
After all the testing and prepping her for her spay she was put under anesthesia…Lilly as we found out was very sensitive to things including the anesthesia. Lilly had an adverse reaction to the anesthesia…she spiked a fever and her condition took a turn for the worst. Her spay could not be performed and Lilly had a very hard time pulling out of the anesthetic state and she was not herself for days.
You can imagine how scared we were for her and then to find out she would have to go back in a couple of weeks to attempt her spay again. Yes, she went back (we were nervous wrecks) and a different anesthesia (induction with isoflurane gas) was used…she still did not handle it well but they were able to get her spayed. Needless to say, we were relieved to get her back home.
After about a month or so, we noticed Lilly acting rather odd…she was doing all the symptoms of a cat in heat. She was rolling on the floor and rubbing her head and body against objects. Along with the rolling, she was flexing her claws and stretching and adopting the posture suggestive of a desire to mate - tail raised, rear end elevated. Fortunately, we did not have the excessive howling; the spraying of urine or the desire to escape the house that often times accompanies a cat in heat.
When we talked with the vet, we were assured that her spay had indeed been done and that there was no way possible for her to ever get pregnant. The vet mentioned that it is common for a pet to experience a false heat shortly (usually within a 30 or so day period) after spaying. So, at this point, we decided to wait and see if this was the case. Well… Lilly had several more heat episodes thereafter and has them a couple of times a year. The vet stated that they could do exploratory surgery on her as there may be some residual ovarian tissue. Obviously, we were not thrilled to hear that suggestion.
We were told that not having the surgery done would not be an issue but that we would have to deal with her behaviors periodically. After doing some research, I found a few other people who had cats do this very same thing although it is rather rare. One in particular, had the exploratory surgery done twice and yielded no results.
Sometimes there is ovarian tissue in locations other than the expected ones but more often a small portion of the ovary is left in the abdomen during surgery. This must be reasonably easy to do because there is a lot of attention paid to this problem in books dealing with surgery and reproductive disorders. If you do have a cat experiencing the signs of estrus after being spayed, the advice is to have the exploratory surgery done when the cat is exhibiting signs of estrus, if possible. The ovarian tissue will be easier to find then because the developing egg makes it larger. It is also reasonable to do it shortly after estrus when the remains of the egg are present since they are sometimes easier to feel and see due to their consistency and coloring. Finding it and removing it should resolve the symptoms.
If there is any question about whether or not a real estrus period is occurring, examination of vaginal smears and hormonal testing may help to confirm what is going on. Vaginal smears are easy for most veterinary practitioners to do and to interpret fairly reliably. Hormonal testing is less likely to be a routine procedure for your vet (at least in cats) and it may be a good idea to ask about a referral to a veterinary reproduction specialist, if you get to this point. Even though this is a much more involved process it may be warranted.
Due to the fact that she is too sensitive to anesthesia, hates to ride especially to see the vet and her heat symptoms are mild… we have opted to let it be.