False Pregnancy or Pseudopregnancy in Dogs
What is meant by false pregnancy?
False pregnancy, phantom pregnancy, pseudo-pregnancy or pseudocyesis are all terms that refer to a display of maternal (mothering) behavior combined with the physical signs of pregnancy following estrus ("heat") in a female dog that is not actually pregnant. A false pregnancy may occur in a dog, regardless of whether or not she was mated. The majority of intact female dogs will show some signs of false pregnancy after an estrus cycle.
What are the signs of false pregnancy and when do they occur?
"...mimic the symptoms of true pregnancy."
Symptoms of false pregnancy usually begin four to nine weeks after the previous heat period, and mimic the symptoms of true pregnancy. The more common signs of pseudo-pregnancy include mammary gland enlargement with or without the production of milk, lethargy, periodic vomiting, and fluid retention. The female often has a decreased appetite but seldom appears to lose weight, probably due to the amount of excess fluid she retains.
These symptoms can occur at any age and do not necessarily follow every estrus. The severity of the clinical signs varies between individuals and may vary from one cycle to the next in the same dog.
Behavioral changes of pseudo-pregnancy include nesting, mothering activity, restlessness, decreased interest in physical activity and occasionally even aggression. Some affected dogs will show signs of a false labor and then protectively guard toys or other small objects.
Why do these symptoms occur?
"After an estrus cycle, her ovaries begin to produce hormones..."
After the female dog has an estrus cycle, her ovaries begin to produce hormones, regardless of whether she is pregnant or not. These hormones prepare the uterus to receive the fetuses and maintain pregnancy. If the dog is pregnant, the hormones will continue to be produced until shortly before the puppies are born. If she is not pregnant, the levels of the hormones begin to decline after 4-6 weeks. In the early stages, the increased levels of circulating hormones cause changes that mimic pregnancy. As the hormone levels decline in the non-pregnant dog, they send signals to the body that stimulate false labor and mammary gland development. The reason that these hormonal changes occur in the non-pregnant dog remains a mystery.
How is false pregnancy treated?
"Mild cases of false pregnancy do not require treatment..."
Mild cases of false pregnancy do not require treatment since the symptoms will subside in approximately 14-21 days.
If the dog appears physically ill or the behavioral changes are severe enough to cause concern, treatment is indicated. Treatment is symptomatic, and may include tranquilization to relieve anxiety, treatment with diuretics in order to reduce the milk production or relieve fluid retention; in rare cases, hormonal treatment may be required.
If the female will not be used for breeding, ovariohysterectomy is recommended to prevent future episodes. Ideally, this surgical sterilization should be performed after all symptoms have resolved. If she is surgically sterilized while she is experiencing signs of pseudo-pregnancy, symptoms may continue for several weeks despite the fact she has been spayed.