Clients think I am kidding when I make this diagnosis. In actuality, false pregnancy can and does occur in dogs, cats, mice and occasionally in humans. It is a bizarre condition that can be explained medically and physiologically. Medically, it is known as pseudocyesis. It is caused by an imbalance of hormones and is seen most frequently in unspayed dogs, and less so in unspayed cats. The “pregnancy” hormone, progesterone, is usually produced by the ovaries after a mating occurs, but on some occasions cysts develop on the ovaries and the progesterone hormone is produced without mating, and in excess. This causes changes in the body that manifest itself in some bizarre behavior that includes “mothering” a toy doll, making a nest in preparation of having a litter, seeking solitude as if going into labor, enlarged mammary glands, milk production, and even dripping milk. Pseudocyesis is a self limiting condition which subsides after six weeks, but during the time of symptoms it is overwhelming to the pet as well as the owners. It can and does reoccur, usually after the dog or cat goes into heat again. The veterinarian usually has to take an x-ray or perform an ultrasound to make sure it isn’t a real pregnancy. The only cure and permanent prevention is spaying, which is also known as a panovariohysterectomy: the removal of the ovaries, horns and body of the uterus. It can be done at any age, but this procedure is recommended to perform before the dog or cat ever goes into heat. It prevents real pregnancy, false pregnancy, mammary cancer, ovarian cancer, uterine cancer, and infections in the uterus known as metritis or pyometritis.