What Is a Runt of a Litter?

"Clifford the Big Red Dog was a runt and he is my hero."
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When choosing a new puppy or kitten from a litter, you may find yourself drawn to the small runt fighting for attention. As many animal shelters report, these runts draw on the natural protective instincts of people and are usually the first adopted. However, there are often special considerations.

What is a Runt?

A true runt is an animal born with unusually low birth weight. Almost every litter with multiple animals will have newborns ranging in weight, but a runt’s birth weight will be below the normal birth weight range. For example, in a litter of pups, you may have puppies ranging from 8 to 10 ounces. The runt may arrive weighing only 6 ounces. In most cases, this lack of growth has to do with where the little guy developed inside the uterus. Runt placement is usually farthest from the source of nourishment, resulting in a lower birth weight.

Possible Complications

Because of their smaller size, human intervention after birth is sometimes necessary to ensure these smaller animals get the food and nutrients they need to grow and thrive. Their size often finds them battling with their siblings at feeding time, which sometimes necessitates bottle-feeding. Fading puppy or kitten syndrome is a concern with any newborn, but especially with runts. Weight gain must be monitored closely. If a runt is not gaining weight, a veterinary check is necessary. In addition to low birth weight, runts also may suffer with other developmental issues such as weak bones, underdeveloped organs and heart issues. As with any new puppy or kitten, have your vet perform a thorough examination to rule out any medical concerns.

Happy and Healthy Pets

Like a preemie baby, runts may start out small but that doesn’t mean they will stay that way or suffer any long-term medical issues. In fact, many runts often grow up to be the largest animal from a litter. George, a great Dane who made it into the Guinness Book of World Records as the tallest dog, began life as a runt.


In general, runts that survive to 6 to 8 weeks of age will go on to develop similarly to their litter mates. After bringing your new runt home, have your vet give him a thorough examination to rule out any development issues and possible medical conditions. Feed your new puppy or kitten quality food at the recommended serving size. Do not assume that he needs more to catch up. If he is not gaining weight or developing as he should, consult your veterinarian about possible supplements he may need.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.

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