Canine physiology is sometimes confusing. Dogs may retain some of the instincts and some of the bodily functions their ancestors had in their wild past. False pregnancy, a release of hormones that causes a female dog to start lactating despite not being bred, may be one of these ancestral hold-overs. Lactation due to false pregnancy is an uncommon occurrence, but it is not an abnormal physical state. False pregnancy usually occurs between 6 weeks and 3 months after the dog’s heat cycle has ended.
Some dogs begin to nest or to act as “mother” to toys or other objects after they have gone into -- and have come out of -- heat. These actions are part of a phenomenon called “false pregnancy,” a state of hormonal, not actual, pregnancy. At times, the hormones that produce a false pregnancy can also result in lactation or even labor pains. Both the lactation and the other symptoms of false pregnancy typically disappear on their own after several weeks, as the female dog’s hormones return to normal.
False pregnancy does not usually require any medical care to make it cease. If the symptoms are severe do not stop on their own, it's possible to sedate the dog to bring the false pregnancy to an end. Once the dog is no longer in heat, the best way to stop false pregnancy from occurring again is to spay her. It's best to wait to spay her until after the false pregnancy has stopped to avoid extending the presence of symptoms.
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