Dogs and cats are litter-bearing animals. Your pregnant pet can generally anticipate bringing5-8 little wigglers into the world on a single night. Each female cat or dog is capable of performing that feat several times during her lifespan, of course. These numbers vastly exceed the fertility rate needed to keep our pet populations stable, which is why veterinarians and humane society folks are so eager to facilitate those spay and neuter surgeries.

Occasionally, however, something weird happens. A pet pregnancy is examined and found to contain only one baby. That infant is called a “singleton”, and in a litter-bearing world, singletons face more obstacles than you might guess. First off, a lone fetus can grow quite large in utero, and I’m sure you know that an oversized offspring (of any species) is difficult to deliver. Cesarean section surgery is quite common in singleton pregnancies, especially for dogs, so prepare yourself for that event if you’ve recently found out there’s only one bun in the oven.

A second reason that singleton pregnancies tend to be more complicated is the actual onset of labor. Birthing is initiated by hormones that come from the fetuses, and the amount produced by a single fetus is often insufficient to start the process. Again, this is particularly a problem for our canine friends. It is actually possible for the mother’s body to forget completely about what she had in the oven. The nutrition supply in there expires after about 8 weeks; when that happens, all puppies need to be on the ground. If they aren’t, the consequences for both parent and offspring are disastrous.

A planned C-section is quite safe for singleton pregnancies, especially compared to the alternative. The challenging part is timingthis procedure correctly. Fetal development must be complete before a C-section is performed, and that finish line can be surprisingly difficult to estimate—even if the precise breeding date is known. Knowledgeable breeders often conduct blood tests prior to the mating, because a simple calculation using that datawill tell exactly when to perform surgery. However, most amateur and accidental breeders haven’t obtained these. A typical (full house) pregnancy will signal its completion with subtle shiftsin body temperature and hormone levels, but these changes may be absentwhen a single fetus is at the wheel.

There are still two strong options for ensuring the safety of your dog and her singleton offspring, but I warn you that neither one is cheap. Multiple ultrasound exams, conducted by a highly trained operator, can assess the pup for readiness using minute changes in the appearance of its organs. A second option is renting a pregnancy monitor online. Theseareinvaluable for detecting labor complications, and the best companies provide a package including abundantaccessto customer support.

Single-pup pregnancies are surprisingly risky for both mother and infant. To ensure the safety of both, start making preparations and weighing the options as soon as you receive this news from your vet.Maybe start moving some money around. The effect on your peace of mind will be priceless.

Dr. M.S. Regan