Runt of the Litter Term Explained

Runt of the Litter Term Explained

Author WDF Staff


Dog breeding is not an easy thing to do. It involves hours and hours of studying genetics, pedigrees, breed traits, and a breeder should have a clear goal as to why they are breeding dogs. In cynology circles, it is a common thing that a specific breeder needs to have a clear goal as to what they want to achieve with a specific breed. For example, if a breeder is breeding German Shepherds, are they breeding them for their looks or working characters? Does he want to breed dogs ideal for dog shows, or do they want to breed strong, intelligent service dogs?

There are different terms breeders need to know, and one of those terms is “Runt of the litter.” This is not a veterinary term. It is a common term used by owners and breeders to describe the smallest and weakest puppies. At first, you might think small puppies will need protection and help, but that is not always the case. If you are looking for a puppy or just want to know more about what runt of the litter means, stick with us, and we will let you know.

What is the runt of the litter?

Dogs can have litters of 1 - 10 puppies, depending on the size and the breed. Just like in human babies, not all puppies are born the same. Some puppies are bigger, more outgoing, and confident than others. The runt of the litter is one or more puppies that are significantly smaller than the rest of their littermates. This is especially noticeable during feeding.

In litters that have more than 6 puppies, mealtime can become hectic. Nursing female dogs can have 6 - 10 nipples, and sometimes, puppies need to wait their turn to eat. Larger puppies might want to bully their siblings and always go first for the mother’s nipple. The runt of the litter, the smallest puppies, usually have to wait their turn. It is not uncommon that they end up not having enough milk, which will affect their development. It is a vicious circle that might require human intervention.

At first, noticing puppies that are the runt of the litter might be problematic. Over time, the difference in development will become apparent, and smaller puppies would not survive in the wild. Natural selection demands some degree of competition, and bigger, stronger puppies will always eat first and get the best and warmest spots for sleeping.

How does the “runt” happen?

There were many theories as to why a runt of the litter happens. One of the first theories is that the smallest puppies, or the runt, were conceived during the second mating. Dog breeders usually mate their dogs at least two times to make sure the pregnancy happens. The second mating will take place 24 hours after the first one, and some vets said that the runt of the litter got conceived during the second mating. That theory was disproved as soon as vets learned that all the mother’s eggs are fertilized at the same time or very close to it.

The definitive proof to why the runt happens can be found in Dr. Kustritz’s bookThe Dog Breeder’s Guide to Successful Breeding and Health Management,” where she explained that the smallest puppies simply had a bad implantation site in the uterine horn. Unfortunately, the poor uterine placement sets these puppies up for a lifetime of problems.

Misfortunes of the runt

From the moment these puppies are born, they are at a disadvantage. Their smaller size makes them often unable to feed, keep warm, and they are often bullied by other puppies. This might seem cruel, but there is little place for sympathy in the wild. Puppies or cubs that didn’t develop properly would rarely live long enough to become adults. However, being unable to feed is just the first problem the runt of the litter will face. Even if they are hand fed and saved by humans, other ailments can bother these puppies.

Unfortunately, poorly developed puppies are prone to different health issues. A common condition among the runt is seizures. Check out this article for more information - Seizures in dogs.


The runt of the litter puppies had bad luck from the moment they were a fetus. After they are born, other puppies will bully them, and they will have problems with feeding. The real issue begins for them when their mothers start ignoring them. The mother’s instincts tell her that the smallest puppy will not survive, so she is saving her “resources” (food and warmth) for other puppies. The runt of the litter is often ignored by their mothers, and if the breeder or owner doesn’t interfere, the puppy will most likely not survive.

golden newborn puppy

Prone to diseases

The worst thing about the runt of the litter is that they are prone to different diseases and conditions. Some of these conditions might be mild, but others can be severe and life-threatening. It is essential that breeders recognize and identify the runt and help speed up their development. These puppies will need to be hand-fed, and they will require special care.

One common condition noticed with the runt of the litter is hydrocephalus. Check out this article to learn more about this health condition - Hydrocephalus in dogs.

What to do with the runt?

In the wild, the runt of the litter rarely survives their infancy. However, at home, with caring breeders, the runt of the litter can not only survive but thrive and develop in the best possible pet. The critical thing is to help the poor puppy from the moment they are born. Make sure you are in contact with your vet, and as soon as the puppy is born, the vet should check them for any congenital diseases. If the puppy has a severe deformity, sometimes, the only thing left to do is to put them down. That is, of course, the last thing you should do, but some puppies are beyond saving, and leaving them alive can be excruciating for them.

If you are interested in small dogs, why not check out the full list of the smallest dog breeds? Check this out - Small dog breeds.

white newborn puppy

Teacup dogs and the runt of the litter

The runt of the litter is one way of creating teacups dogs. These runts are usually the smallest and weakest, and they are generally spayed or neutered early. What you should never do is further breed the runt of the litter. These poor puppies have bad genes, and allowing those genes to be passed to further generations is very irresponsible and risky.

Teacup dogs are prone to different diseases, and this is usually the main reason why. Irresponsible and unethical dog breeders use the runt of the litter to create even smaller and weaker puppies. These new puppies are often called “teacup” and are marketed as being “unique” or “rare.” The truth is, teacup dogs are unhealthy, and if you are a true dog lover, you should never buy a teacup dog.

If you want to know more about teacup dogs, check out this article - What are teacup dogs?

World Dog Finder team

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