Neutered male trying to mate with spayed female

[furacious]

Ok, so I plead a nice, embarrassed ignorance until I googled a few things tonight. 

We adopted our four cats from March through last week, all from the same shelter. They are really amazing! 

Here's the issue:

Fred (ginger male tabby, approx. 8 mo., neutered, adopted in May) is NONSTOP chasing Lucy (approx. 1 y/o, spayed, adopted in March). They chase, play, pawfight, etc...BUT he also tries to bite her neck and mount her repeatedly. I noticed the behavior in the last 1-2 weeks, more so the past week. He completely ignores any biting/mounting behavior with our other two spayed females and is relaxed around them. 

How do I figure out if this is a failed spay/neuter...and as he is ignoring the other girls should I logically assume it is an issue with Lucy? If so, is that now part of my ownership responsibilities or should the vet who made the mistake fix it? 

Although I had many animals growing up, aside from chickens, and a goat...these sweet cats are our first indoor animals as adults. 

At first I simply thought they were very playful with each other, but the behavior is progressing towards problematic the last few days. He literally won't leave her alone. 

 

[margd]

Has Lucy shown any signs of being in heat?  Although it's rare, sometimes bits of ovarian tissue are left behind during the spay operation and females continue to show signs of going into heat.  This might explain Fred's interest in Lucy.  Some neutered males do attempt to mate with intact females. I've had this happen among my own cats.  The easiest way of determining if Lucy was incompletely spayed is to look for other signs of her being in heat, such as yowling or rubbing against everything in sight.  If she's not doing this, there is a test that your vet can run to test for residual hormones being emitted by left behind ovarian tissue. An ultrasound can also be used to image any remaining ovarian tissue, although it doesn't always show up. 

If Lucy has been incompletely spayed, I personally think the vet who performed the operation should correct the problem free of charge.  Your vet might not agree, however, and sometimes will only offer a reduced price for the second operation.

It is also quite possible that Fred is simply trying to exercise his dominance over Lucy.  For whatever reason, he feels challenged by her.  You need to break it up every time he mounts her. Say NO in a loud voice and get between them.  Some people find it helpful to use a towel while doing this. You can also get some canned air, like Dust-Off and spray it when he's acting up.  Sudden noises will often interrupt the behavior.   .After you've broken them up, put him on a time out for a few minutes.  It might take awhile but he should eventually get the idea. 

You might also purchase some Feliway diffusers .  These can help reduce aggression in cats.  They are fairly expensive, however.  Amazon is said to have the cheapest prices.  Also, remember that one diffuser only covers 700 - 900 square feet. 

I would definitely speak to the vet about this.  For one thing, you might want to have Lucy examined/tested for residual ovarian tissue.  For another, the fact that this is relatively new behavior means it's worth checking out just on general principle.  It's always a good idea to have a cat checked by a vet when (s)he starts behaving differently than before.

 

[furacious]

Thanks for your answer! I observed the behavior a little more and spoke to the shelter also. My kids mentioned a stray had been wandering into the yard recently and Fred and Lucg are both big window watchers. I had the thought it might be redirected aggression. The shelter staff felt it sounds more like a dominance issue or the redirected aggression.

Separating Fred to our lower level with another of our cats he has no problems with has kept the chasing and fighting at bay. I am reintroducing them bit by bit and it seems to slowly be easing with less incidents during supervised times.

 

[margd]

Redirected aggression does make sense.  I'm glad to hear things are going a little more smoothly - reintroducing them was a good idea.  Here's hoping they will all be buddies before too long! 

 

[furacious]

We had an aha moment!!! I walked into the cat room downstairs. It is below ground so window is eye level with ground outside. Guess who was hanging out 1 inch from the open window blinds? A beautiful grey/white stray that we have sighted three times in our yard in the past week. Helloooo redirected aggression! I dropped the blinds and put out food (out of sight) outside. Hope to trap him/her soon and take him to our favorite shelter so s/he can find a furever home.

Too bad I cannot edit the title to get advice on luring the sweet stray!