Should I get the runt of the litter?

Q: I'm looking at a litter of puppies, and one is very small. Is it OK to choose the runt of the litter, or are there reasons not to? And what causes runts?

A: A runt is an animal that's unusually small, most often the smallest in a litter. There are several reasons for variations in the size of newborns. A runt might occur in a very large litter because of positioning in the womb or because matings took place over several days.

Several factors affect whether a runt might be a good choice as a pet. Some runts are small because they were born with physical abnormalities affecting the heart or digestive system. So you'd want to make sure your pup has been checked by a veterinarian who's knowledgeable about what to look for overall as well as in a particular breed.

Runts don't always have physical health problems, but their size means they need to have gumption to survive. It takes a sturdy, strong-willed little pup to muscle its way into the chow line and get its fair share. Good breeders can help by providing a little intervention to ensure that the runt gets a good spot at the milk bar.

It's amazing to see how pups grow, and it's not unusual for the littlest of the bunch to catch up to the others. By the time a litter is a year old, the puppy who was born the runt may have caught up with its littermates in size — or may even have turned out to be the biggest of the bunch.

A runt who survives young puppyhood can turn out to be a great choice as your new best friend.