Is it possible for a spayed female dog and a UN neutered male to mate?

We recently got a new dog. Im not sure how old she is but she is of adult age. The previous owner said she was spayed.. We already have a UN neutered male. Since bringing her home she was acting like she was in heat. She was constantly trying to get my male dogs attention. She would go crazy to be with my male. She even looked to be swollen down there. I caught them stuck together a multiple of times. A week or so later they both have no sexual interest in each other and she looked to not be swollen in her private area anymore. Now three weeks later her nipples appear to be a little swollen. Is this possible for a spayed dog or was I lied to about it?
Asked Apr 26, 2017

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