Ask the Vet

Puppies, Puppies Everywhere

A litter of puppies can have multiple sires, which may explain why littermates can look so different sometimes. (Shutterstock)


We had a stray dog that had puppies in our barn. The puppies are all so different. Different colors and sizes. I have heard that there can be more than one father to a litter. Is this true?


Yes, there can be multiple sires to a litter of puppies. The same is true for litters of kittens.

Unlike cows, dogs can stay in heat for several days. During this time, the female can, and often will, mate with more than one sire if they are not confined. Some recent research with dogs shows that litters from multiple sires are often larger and that the second sire often fathers more of the pups than the first sire.