It is not difficult to diagnose false pregnancy in dogs. If the animal went through a heat cycle 6 to 12 weeks before the onset of clinical signs of pregnancy, whether or not she was known to be bred during that time, a veterinarian will take a thorough history of her recent physical and behavioral conduct and will perform a complete physical examination. Radiographs and ultrasound can be used to conclusively confirm the presence or absence of pregnancy, and no additional blood, urine or other tests should be necessary. Of course, since a dog’s gestation period is only roughly two months, if 3 or more months have passed since the end of a bitch’s previous heat cycle it is highly unlikely that she is truly pregnant.
Radiographs and ultrasound are also useful to rule out the possibility of a serious condition called “pyometra,” which is an accumulation of pus inside the uterus from bacterial infection. Pyometra can be life-threatening and must be treated as an emergency. It is uncommon, but still possible, that signs of false pregnancy will appear in a bitch who actually became pregnant and then either aborted or reabsorbed her puppies, in which case the risk of developing pyometra increases dramatically.