
Well she should not have had the opportunity to get caught in kennels, uless she was kenneled or excersised with other dogs. This can be checked by contacting the Kennel.
It is possible for a bitch to have a silent season, and to be mated, and have pups, but you should have noticed any resident male showing more than usual interest, and the same on walks.
She could be having a phantome preganancy, have qa womb infection, or have just got fat from overeating (possibly fed too much in kennels).
I would get the vet to look at her if she is behaving listlessly, drinking more than usual,or just to put your mind at rest.