A physical examination by the veterinarian along with a history of known breeding attempts and last heat cycle can identify whether the dog has become pregnant or not. (texaswestveterinarian.com)
Females who were in heat when the spay was performed should be kept inside for at least a week to minimize the chance of breeding attempts by males which can result in serious injury. (cattime.com)
The female deserts her mate and brood about the time the chicks hatch and initiates a new breeding attempt with a different male. (nps.gov)