We are currently fostering a canine family consisting of seven puppies (Cosmo, Piper, Pompeii, Sterling, Max, Snoopy and Cheyanne) and their mama, Daisy. Curiously, the puppies look very little like their mama, so we figured they must look a lot like their daddy. But as they grew, we continued to be quite puzzled as to what daddy might have looked like. Was he a black Scottie dog like Piper and Pompeii? Or more beagle-ish like Snoopy and Cosmo? Was he long-fured and shitzu-ish like fuzzy little Max? Or was he more like Cheyanne and Sterling, who seem to be a mix of terrier and dachshund?
As we considered all of the possible combos of a dad who could have sired so many different looking puppies, someone said “Well, you know, they could have different fathers.” That was news to me. More than one dad per liter? But it made complete sense looking at our diverse tail-waggin’ menagerie.
So, I looked up the breeding ecology of dogs and sure enough, it is common for a litter of pups to share one mama but have different daddies. Female dogs release multiple eggs during ovulation and are thus capable of conceiving every time they mate during this period. Interestingly, the eggs are actually not fully mature upon ovulation. They complete the maturation process in the uterine horns. Furthermore, male canine sperm can cling to the uterine lining for days and then release when viable eggs become available. This scenario often results in multiple fathers for one litter. I double-checked these facts with the Humane Society vet, Dr Paul Chapin, and he said indeed it is true that dogs can conceive every time they mate over the three week period that they are fertile.
However, if the matings happen too far apart, one batch of pups will be ready for birth before the other later-conceived batch and the younger ones may not be viable when the first batch is born. If the younger pups are viable, then they may be developmentally behind the others. This could have been the case with at least one of our pups, fuzzy Max. We at first thought he was merely the runt, but then when all of the other pups cut their teeth before he even showed one tooth, we realized he may just be a week or so younger than the others.
Prior to 1998, the American Kennel Club did not allow the registration of litters with more than one sire (father). This is no longer the case, however DNA test are required for multiple sired litters, if owners desire the coveted papers proving a pup is a purebred.
For those of us who are not interested in pedigreed lineages, the idea of multiple sired litters is nothing less than fascinating as in the case of Daisy and her seven pups. (Of course, spaying and neutering is entirely preferred as the world has more pups than loving families available!)
For the record, cats also can give birth to a litter with multiple fathers. From an evolutionary perspective it makes a whole lot of sense for a female cat or dog to mate with multiple males and let the best sperm win. Furthermore, a litter of pups or kittens with diverse genetics is more likely to have survivors than a litter with all the same genetics.
So, now that I know one litter can be sired by multiple fathers, I will never look at a litter wondering who the father is, but rather now, how many fathers were there and what did they all look like.