Q: We were given a ferret by a friend a little more than six weeks ago. We have three other ferrets. Shortly after the new ferret arrived, we realized she was gaining weight. I took her to the vet, who said he thought she was pregnant. The friend we got her from has a neutered, male ferret that our new ferret, Fern, had recently been in with. The vet explained that sometimes the neutering doesn’t work, and the male ferret can still be fertile. However, our friend has also used the ferret on his own intact, female ferret and she isn’t pregnant. Is it possible this is a phantom pregnancy? I have read that this is quite common after being in with a vasectomized ferret. If so, what will happen and what makes her fat if there are no babies inside? When will she return to normal size? Surely if she was pregnant she would have had baby ferrets by now, right? Is there a definite way to find out? She is in on her own at the moment as the vet said our other ferrets may kill the baby ferrets if she does give birth.
A: OK, this sounds like the Peyton Place of ferrets, and the story is a little difficult to follow to understand who has been with whom, but I have an easy answer to your question. If you received the ferret more than six weeks ago, that means more than 42 days have passed since you acquired your ferret. Because gestation is, on average, 42 days in ferrets, it is likely your ferret is not pregnant as she should have given birth by now.
If your ferret was pregnant, not only would the belly enlarge, but the mammary glands would also greatly enlarge. Even if your ferret was pregnant and had stillborn kits, there would still be enlarged mammary glands. Plus, if the kits are stillborn and they are still contained in her uterus, at this point, she should be appearing very sick.
Based on your description, I am assuming that your ferret has an enlarged abdomen but is not sick. Animals may have something called a “false pregnancy,” which causes hormonal and behavior changes not associated with feti. In those cases, it is uncommon to observe an enlarged abdomen.
An easy method to determine what is causing the enlargement of your ferret’s abdomen is radiographs. If she is truly pregnant, by this point in the pregnancy, skeletons of the feti should be visible, even if they are stillborn, skeletons will be visible. If the abdominal changes are from fat, fluid or an enlarged internal organ, your veterinarian should be able to see that, too.
The best answer to this dilemma is to take your ferret back to the veterinarian to determine exactly what is causing the enlargement of your ferret’s abdomen.