My in-laws had a little 4lb malti-poo that never acted interested when she was in heat so they never worried about her. When she was 8 she started gaining weight but they never suspected a pregnancy until they found her under the bed trying to deliver a huge puppy. The vet figured that a lab had got a hold of her. My in-laws were lucky she didn't die so if you are going to spay her it is better late then never plus they say it reduces the risk of certain kinds of cancer.
