Caroline Coile, Ph.D., is a breeder, owner and handler of top-winning Salukis and the author of 19 books, including The Barron's Encyclopedia of Dog Breeds, andCongratulations! It's a Dog! Buy at Amazon.com.
In a false pregnancy, some intact bitches will treat dog and child toys as a puppies gathering them close and often encouraging them to nurse.
As Lorna Boydston's Great Dane approached her due date, she gave every indication that a big litter was on the way. She was huge, and as Boydston described her, "a walking dairy bar." Labor began, but after hours of straining no puppies were produced. A certified vet tech, Boydston, of Colbert, Wash., couldn't feel any puppies, so she took the bitch for a radiograph - which showed why. There weren't any puppies. Yet the labor continued for another 36 hours.
Coffee, a Labrador Retriever mix and the childhood dog of Glenda Parks, of Baton Rouge, La., had a huge litter. She was a doting mother, gathering them up to nurse whenever they strayed. She had one favorite, though, that she would lay with for hours, encouraging it to nurse; everyone in the household, dog and human alike, knew better than to touch the special baby. The puppies bore little resemblance to their dam, however; like the special puppy, which was in fact a plastic toy hamburger, they were all dog and child toys.
Idibidi, a Doberman Pinscher owned by Kim Floyd, of Riverview, Fla., bypassed the need for puppies by licking and suckling her mammary glands. This, in turn, encouraged milk production, and she became her own snack bar. Unfortunately, Idibidi eventually developed mastitis, and then mammary tumors, necessitating spaying and breast surgery.
Like 87 percent of intact bitches do at least a couple of times in their lives, these bitches were experiencing what's called a false or pseudopregnancy. All non-pregnant bitches have increased mammary development between six and 20 weeks following estrus, with maximum size occurring around 14 weeks after. This is a normal part of the canine estrus cycle; however, in some bitches the signs become extreme, causing what is called clinical or overt pseudopregnancy.
Mammary enlargement and milk production are the most common signs of overt pseudopregnancy, but other signs include enlarged abdomen, nesting behavior, decreased activity, aggression, and maternal behavior often aimed at inanimate objects. Some bitches even appear to go into labor, complete with abdominal contractions. The more convincing cases cause accusations of "who let the dog out?"
Usually, nobody. This convincing charade occurs because intact bitches undergo the same hormonal changes during diestrus whether they were bred or not. There's some evolutionary support for the idea that having related bitches available as a milk reservoir and nanny service would be beneficial enough to select for this ability. Exactly what causes it, and why it is more pronounced in some bitches than others, is not totally understood, but it basically can be traced to the hormones progesterone and prolactin.
Progesterone levels initially increase, then later decrease during diestrus in the same pattern in both pregnant and non-pregnant females. Elevated progesterone levels are necessary for mammary enlargement, but it is the prolactin that stimulates milk production. Prolactin normally rises during late diestrus in pregnant, and to a lesser extent, non-pregnant bitches. This rise occurs along with the decrease in progesterone, and some evidence suggests that a faster than normal drop in progesterone may cause increased levels or sensitivity to prolactin, thus bringing on lactation in non-pregnant bitches. That may be why spaying a bitch (which causes a precipitous drop in progesterone) during diestrus often (but not always) brings on pseudopregnancy within several days. In fact, the bitches that are more likely to develop pseudopregnancy after spaying during diestrus are usually those that already have a history of pseudopregnancy, suggesting that some bitches are more sensitive to the effect of decreasing progesterone levels.
Pseudopregnancies seldom cause harm, but they can occasionally lead to mammary discomfort or even mastitis, and recurring pseudopregnancies have been linked to subsequent mammary tumor development. Mostly, they are considered a nuisance. They interfere with a bitch's show or performance career. They can cause high stress levels and aggressive behavior. Although most cases will run their course in two to four weeks, many owners seek ways to make the signs go away.
It may he possible to treat symptomatically. If she is continuously licking or nursing from her own mammary glands, a T-shirt, belly wrap, or Elizabethan collar may thwart her. The continued stimulation of the glands will otherwise tend to encourage further milk production, which is why applying compresses or "milking out" the glands is usually counterproductive.
If her problems are behavioral, giving her a mild tranquilizer may do the trick. It's important that the tranquilizer not be from the phenotiazine family, which includes the popular tranquilizer acepromazine. Drugs from this family stimulate prolactin secretion, and thus increase milk production and other symptoms.
Because few therapies are widely available, breeders often resort to using natural remedies such as peppermint. Some report good results; others don't.
The most widely used veterinary therapies have traditionally been based on sex hormones; unfortunately, their side effects usually outweigh their benefits. Estrogens, such as diethylstilbestrol, are not recommended because they can cause uterine disease. Progestins, such as megestrol acetate, can also predispose to pyometra and mammary tumors; in addition, as soon as treatment is stopped the signs are likely to reappear. They are likewise not recommended. Androgens, such as testosterone or mibolerone, can alleviate signs of pseudopregnancy, but they are difficult to obtain.
More effective are prolactin suppression therapies, which combat pseudo pregnancy by acting on neurotransmitters that control prolactin secretion. Bromocriptine is a human drug that is effective, but its side effects of vomiting make it less optimal than other drugs in this class. Cabergoline and metergoline are both effective with fewer side effects, but neither is available in the United States for veterinary use. Both are marketed for veterinary pseudopregnancy therapy in many European countries.
Before treating your bitch for false pregnancy, you have to be positive it's not a true pregnancy. Abdominal ultrasounds and radiographs can be used to determine if the bitch is pregnant or if she may have pyometra, which could cause some similar signs. Otherwise, sometimes not even your veterinarian knows for sure.
Some years ago Suze Schlenger, of Pleasant Valley, N.Y., commented to her then husband that one of his retrievers, Sandy, looked pregnant. He replied he had just returned from the veterinarian, who had pronounced a false pregnancy. A long debate ensued, until Schlenger ended it by saying, "If she is not pregnant then what is that on the floor?" It was the first of seven real, not pseudo, puppies!