Following your dog's heat cycle she begins to show signs of impending pregnancy. But you are positive she hasn't been bred. Your female may be experiencing a normal physiological phenomenon known as a pseudopregnancy or false pregnancy. The female is basically receiving mixed signals following her heat cycle. False pregnancies are well recognized by breeders and veterinarians.
False pregnancies can occur in both young and older dogs and can recur with subsequent heat cycles.
She notes that no one is really sure why some non-pregnant dogs exhibit signs of a false pregnancy and others do not. The signs of false pregnancy usually begin 6 to 12 weeks after standing heat. The female may appear bloated, develop enlarged mammary glands and lactate. She also may act restless, nervous or excitable. The dog may also vomit, refuse to eat, have diarrhea or nurse herself.