If your unspayed female dog starts behaving like an expectant mother, but you're certain she wasn't bred during her last heat cycle, she's probably experiencing a ghost pregnancy. Also known as pseudopregnancy, phantom and false pregnancy, the condition isn't uncommon in intact female dogs. Take her to the vet for an examination and pregnancy testing. If she was ever unsupervised during heat, pregnancy is a possibility.
Symptoms of ghost pregnancy appear between one and two months after the dog went out of her heat cycle. Her stuffed toys may suddenly become her "puppies." She'll gain weight, especially in the abdomen. Her nipples might produce milk. Her behavior might change. She'll be constantly "nesting," trying to find a suitable place to have her phantom babies. However, some dogs experiencing ghost pregnancy might become aggressive or exceedingly anxious.
Your veterinarian will physically examine your dog, and perform blood tests and urinalysis, to rule out an actual pregnancy. She might also X-ray your dog's uterus to make sure your pet isn't suffering from a uterine infection. Since certain liver ailments and hypothyroidism can change hormone levels and mimic some of the signs of false pregnancy, your vet will also screen your dog for these disorders.
During and after her heat cycle, your dog's body produces a lot of hormones. Her body is hard-wired for pregnancy, so her ovaries kick into gear to prepare her womb for puppies. If she isn't bred, or the breeding didn't result in fertilization, the hormone levels should eventually taper off. But until that occurs, her body will react as if she's expecting, including swelling of the nipples and milk production along with behavioral changes. Some canines even experience feelings akin to labor.
Since your dog isn't actually pregnant, the symptoms will eventually go away on their own. If she continually experiences false pregnancies after her heat cycle and you have no intention of breeding her, spaying should permanently end the problem. Meanwhile, you can place an Elizabethan collar on her so she can't reach her nipples. Some dogs might lick their nipples, which promotes milk production. If your dog produces milk, your vet might prescribe a diuretic to dry it up. She can prescribe hormones to cease production if milk amounts are copious.
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