
It sounds like it isn't relevant in this case, but thought I would mention it as a thought. My old girl (who we lost last year) started to act strangely, put on weight and then her boobs started to grow. I was concerned, she had been spayed before she came to us, and so off we went to the vets. The vet diagnosed that she was having a mild phantom pregnancy and that they had obviously accidentally left behind some ovarian matter when performing her spay that was causing the hormone changes. I asked if that was something that often happened and he replied not regularly, but it is known to happen.
I don't know if the timing of her spay was anything to do with her problems, she had been dumped having been over bred and having very recently had a litter when she was found. The vets thought from examination she had finished doing her bit with the litter and was then dumped. She was spayed soon after she went into rescue as she needed other surgery so they did it all at once. It seems possibility that she was spayed a bit too soon for ideal timing. I don't know whether this had anything to do with the op not being 100% successful, I never thought to ask that.