The Runt of the Litter: Definition, Facts, Health, Care & FAQs

The runt of the litter sleeping on his arms

If you are a fan of miniature or teacup dogs, you have probably heard of the runt of the litter.

They are used in breeding and developing miniature dogs because of their petite physique. However, the canine community gravely condemns this practice as it is considered to be unethical.

If you want to learn more about runts and the controversy that hunts their existence, go read this detailed guide! 

I also plan to debunk the myths commonly attributed to runt puppies, so expect that you’re in for an exciting read.

What Does “Runt of the Litter” Really Mean?

Breeders use the term runt of the litter to refer to the smallest puppy of a breeding stock. The runt of the litter is also believed to be the weakest among all of a dog’s offspring.

However, there are still no clear-cut criteria as to when a puppy can be considered a runt.

So far, the only thing that distinguishes a runt from its littermates is its smaller physique and slower growth. Most of them have low birth weight when they are born.

Aside from having the smallest statures, most runts are observed to be weaker compared to their siblings. Thus, some breeders find them undesirable and unwanted. 

Their smaller body and weak health condition make them more vulnerable to health issues that could hamper their growth and, worse, shorten their lives.

The differences between the physical growth of runt and normal puppies also become more apparent as they grow.

The runt of the litter will have a slower growth rate compared to other pups, making it appear to be perpetually small even when mature. 

Some runt dogs may also show less activeness and enthusiasm than other pups due to impeded development and weak health conditions.

Why Is There a Runt of the Litter? Do Puppy Litters Always Have Runts?

A group of puppies with a runt of the litter sleeping together

Not every litter has runt puppies. Often, a dog may give birth to equally healthy puppies with proportionate sizes and growth.

However, it is not unusual for a dog litter to have small and weak newborn puppies. Yes, you read it right — puppies! In some cases, there is more than one runt dog born in a single litter. 

The book entitled Canine Reproduction and Whelping: A Dog Breeder’s Guide explained that runts are puppies with poor implantation to the uterus. 

Implantation to the uterus refers to a process where a developing embryo makes contact and attaches to the uterus wall until its birth.

Through implantation, puppies inside the womb can get the nutrients they need to develop and grow.

You can somehow imagine the attachment as a tube that allows the mother dog to feed its puppies inside the womb. 

Hence, when a puppy has poor implantation, they cannot acquire the ample amount of nutrition their body needs, resulting in impeded growth.

Meanwhile, the health of the mother can also affect the condition of its litter.

If a pregnant dog is malnourished or not at its optimum health, it will really produce runts. The puppies inside the mother’s womb will compete with each other for the scarce nourishment they are offered.

Common Myths About Runts of the Litter

Due to a lack of research and studies about these little puppies, many breeders have formulated their suppositions to explain the occurrence of runts in dog litters. 

There are two popular breeder myths about the runts of the litter. Let’s discuss them one by one!

1. The puppy in the middle of the uterus will become a runt 

Many breeders assume that the position of a puppy inside the embryo affects its growth and development. 

They theorized that all the puppies implanted or placed in the middle of the uterus will become runts. 

The idea behind this is that the middle of the uterus is far from the chain of nutritious supply needed for growth. While this may seem logical, the explanation doesn’t have a concrete foundation to stand on. 

The placement of a puppy inside the embryo doesn’t affect the supply of nutrients it gets. Instead, the implantation or attachment of the puppy to the uterus dictates the supply of food a fetus receives. 

In addition, puppies also constantly move and change positions inside the womb. Hence, a puppy cannot really stay in the middle of the uterus for a long time.

2. The last conceived puppy will become a runt

The second myth suggests that the last egg conceived or fertilized will develop as the runt of the litter. However, this hypothesis is refuted because all of the fertile eggs are released within the same day. 

Other eggs might be fertilized earlier than others, but all of them undergo implantation or attachment to the uterus at the same time.

Therefore, the time of conception doesn’t really affect a puppy’s growth. Instead, a puppy becomes a runt because of undernourishment due to poor implantation to the uterus.

Physical Appearance: What Does a Runt of the Litter Look Like?

Runt puppies look similar to their normal siblings except for the fact that they have smaller bodies. Most of them are born with low birth weight. 

They are significantly lagging behind their littermates in terms of growth, with their height and weight scaling below the normal size. They may also show a fragile body structure as a result of undernourishment.

In worse cases, some runt pups may also show physical deformities such as bulging eyes, thinning of hair, and crooked legs. 

Newborn runts also have poor suckle reflexes. This physical disadvantage makes suckling milk and nutrients from their mothers difficult, resulting in weakness. 

Temperament and Personality: Do Runts Behave Differently From the Rest of the Litter?

A runt puppy playing with his mom and siblings

For the record, no evidence suggests that runt puppies develop different temperaments and personality traits from the rest of the litter. However, you should expect that a runt will not be as playful and active as its littermates.

You might observe a runt resting and lying on the floor while its littermates are cheerfully running on the open fields. 


The general personality traits and temperament of a runt will most likely be affected by its environment and the training it receives — well, the same is true for other dog breeds, for that matter. 

While a runt might not have the same energy level as the other puppies, it could still be easily trained through proper training and socialization.

Lifespan and Health Issues: Do Runts of the Litter Have More Health Problems?

A runt dog can live as long as a healthy pup provided that you give them optimum care and attention. 

Runts are basically weaker than their normal siblings. Thus, they need extra effort and care from their owners.

Some runts are born with congenital defects due to the anomalies that happen during conception and pregnancy. While some acquire diseases as they grow old because of their poor immune system and low birth weight.

Here are some of the common health problems that runts may acquire:

  • Undernourishment: Most runts have small bodies and weak immune systems because they are malnourished. The lack of sufficient nutrition impedes runt puppy development and growth. 
  • Congenital Diseases: Birth defects such as cleft palate, dwarfism, and cardiovascular anomalies are commonly observed on runts. This is mainly caused by the inadequate nutrition they receive during pregnancy which affects their overall development. 
  • Hypothermia and Hyperthermia: A runt suffering from hypothermia will show symptoms such as shivering, lethargy, stiffness of muscles, dilated pupils, slow breathing and pulse rate, and worse, coma. Meanwhile, dogs that are suffering from hyperthermia have a body temperature higher than the normal range.
  • Fading Puppy Syndrome: Veterinarians use this term in reference to a condition where a particular puppy slowly dies within the first two weeks. It is believed that the underdeveloped immune system and the inability of newborn puppies to adapt to the new environment are the prime culprits of fading puppy syndrome.

A healthy puppy means fewer expenses for you. If you own a runt of the litter, monitor its growth and be aware of these common health problems. 

Prices and Expenses: Are Runts of the Litter Less Expensive?

The price of runt puppies varies from breeder to breeder. Some runts are sold at a higher price because they have surprisingly excellent health conditions. These little puppies are great foundations for miniature dogs. 

Meanwhile, runts that are significantly smaller and weaker than the other puppies in the litter are sold at prices lower than the average puppy cost.

Beware, though, in buying runts of the litter. Some unethical dog breeders sell sick runt puppies disguised as miniature dogs. This is why you should only transact with trusted and reputable breeders.

The bottom line? A healthy runt puppy can have the same price as its normal siblings.

In terms of supplies, you should also expect to cash out a few hundreds of bucks before taking home your runt puppy. 

Here are some of the initial supplies you need to buy before taking a runt puppy home:

Type of ExpenseEstimated Cost
High-Quality Food$50 – $60
Supplements$50 – $100
Food and Water Bowl$20 – $30
Crate $40 – $50
Bedding$40 – $45
Toys$20 – $25
Leash and Collar$20 – $30
Microchip$45 – $50
Cleaning Essentials$40 – $45
Grooming Essentials$30 – $50
Total Initial Cost$355 – $485

Runts may also require puppy supplements to aid their growth and development. These supplements include vitamins and minerals vital for muscle building and bone growth.

In addition, you would also want to save funds for veterinary treatment as runts can easily get sick and injured during their first few months. 

READ NEXT: 13 Ways to Find Free Puppies in Your Area for Adoption (2021)

How to Take Care of a Runt of the Litter

Feeding a runt of the litter formula from a bottle

Although runts may require a bit more attention and care, maintaining them, in general, is pretty easy. In this section, I’ll share some tips you can follow to ensure that the runt of your litter lives a healthy life!

1. Observe its feeding habit

If you noticed that one of the puppies in your litter is a runt, pay close attention to its feeding habit. Sometimes, human intervention is needed for the survival of a weak litter puppy. 

Runts are smaller than their siblings. Hence, they often struggle competing with the other puppies during feeding time. 

Sometimes, you’ll need to pick up the runt puppies from crowded litters and put them near the mother’s teat so they can latch onto it and nurse. 

For cases where the mother doesn’t want to nurse the weak litter puppy, you’ll likely need to hand-feed or bottle-feed it if it can suckle. 

Preferably, the milk should still come from the dam. However, you can also ask a veterinarian for a puppy milk substitute if you cannot get milk from the mother dog.

Meanwhile, human intervention in the form of tube feeding is needed for runts that can’t suckle. 

Usually, a syringe and a catheter are used in this feeding practice. Nevertheless, you should first seek guidance from a reputable breeder or a veterinarian if you are not knowledgeable about tube feeding.

Watch this video to learn how proper bottle feeding is done!

Caring For A New Litter Of Puppies - Daily Weights And Bottle Feeding

2. Maintain the optimum body temperature

Newborn runts, especially premature puppies, are incapable of regulating their body temperatures. This is why they are prone to hypothermia and hyperthermia. 

If the mother is nursing the runt, you need not worry much as the dam’s body heat will keep the puppies at the optimal temperature. 

However, if the mother doesn’t nurse the runt, you should personally monitor and regulate the puppy’s temperature. 

You should regularly monitor your runt puppy’s body temperature and prevent it from dipping below or spiking above the normal body temperature, which is between 99.5°F and 102.5°F.

You can use heat lamps, incubators, warm water bottles, and towels to keep the runt puppy warm. 

According to VCA Hospital, rectal temperatures in a newborn puppy are:

  • First week – 95° to 99°F
  • Second to third weeks – 97° to 100°F 
  • Fourth week – 99.5°F and 102.5°F (normal adult temperature)

Anything below or above the given temperature ranges is dangerous for a puppy. If the temperature of the runt doesn’t normalize even after providing external heat, you should immediately bring it to the veterinarian to prevent further complications.

3. Monitor the runt’s weight

As part of a runt’s health management, make it a point to monitor its growth, especially during the first months. Record the daily weight gain of your runt puppy to ensure that it is within the healthy weight range.

The rule of thumb suggests that puppies should gain 10% to 15% of their birth weight every day. 

If your runt puppy is significantly lagging behind weight gain, there must be something off with its feeding habit, nutritional intake, or health condition. 

Some puppies cannot gain weight because of underlying health issues such as infection, digestive problems, parasite infestation, and dietary problems.

If the tiny runt puppy won’t gain weight and reach the normal size, you should seek veterinary advice to know exactly what stops your puppy from gaining weight. Worse case is that your puppy has health or congenital problems. 

Pros and Cons of Owning a Runt of the Litter

Picking up the runt of the litter has its fair share of pros and cons. Before deciding to take home a runt puppy at home, make sure that you are aware of the following advantages and disadvantages of owning a runt. 

Here are some of the pros of owning a runt of the litter:

  • Some breeders sell the runts of their litters at a much lower price. However, you should be vigilant as some unethical breeders may trick you into buying a cheap runt that is plagued with diseases. 
  • Tending to the needs of a runt could be a rewarding and unforgettable experience.
  • You’ll be able to build a strong connection with your puppy as you shower it with extra love and affection. 

Here are some of the cons of owning a runt of the litter:

  • Runts are vulnerable to illnesses.
  • Runts require supplements since they are born with birth weights lower than the normal size.
  • Some runts have difficulties in gaining weight.
  • They demand extra effort and care.
  • You’ll need to prepare funds for emergencies and vet bills as they can easily get sick or injured.
  • They might have underlying genetic conditions and birth defects. 

If the runt you bought is healthy, then there is nothing much you need to worry about. You can ensure that your puppy will grow normally with a proper diet and an active lifestyle. 

Famous Runts You Should Know About

You might not know this, but there are actually a lot of famous runts in pop culture! Runts are actually well represented in literature and media. There are a lot of novels, tv series, and movies that feature runts as their protagonists. 

Here are just some of the famous dog runts you might know:

Most of these runts are depicted as weak and small in these books and films, but they managed to grow and do astonishing things!

Frequently Asked Questions

A runt of the litter sleeping with its toy

Do Runts of the Litter Stay Small as They Grow?

Not all runt puppies stay small as they grow. Some runts easily catch up with their normal siblings’ sizes when given proper attention and nutrition. 

However, others may remain small due to genetics or underlying health issues such as malnutrition or dwarfism.

Are Runs of the Litter More Aggressive?

No evidence suggests that runts of the litter are more aggressive than the other litter puppies. 

On the contrary, most breeders and dog owners actually attest that runts are more passive than normal dogs. 

Aggression in most puppies is often influenced by the training they receive and the environment where they are raised. Depending on how a runt is trained, it could be an obedient dog or an aggressive puppy.

Are Runts of the Litter Harder to Train?

Runt puppies could be a little demanding but not hard to train. They sure are considerably weaker and smaller than normal puppies, but they can be successfully trained if you have the patience and perseverance.

Can a Female Runt of the Litter Have Puppies?

Female runts can have puppies as long as they don’t have reproductive issues. If they have grown into a healthy, fully-grown bitch, expect them to produce healthy puppies.

Final Thoughts

The runts of the litter can prove to be good family companions as long as they are provided with the care and attention they require and deserve. 

Tending to their needs is only quite demanding during their first months. Once they have gained the energy to be independent, they will be just like any other puppy. 

If you think that you are prepared to be hands-on during the infancy of a runt, then there’s nothing to stop you from getting one. 

There’s nothing more satisfying than seeing the weak puppy you once cared for gradually become a full-grown healthy dog.

John Carter

My name is John Carter and I absolutely love pets, especially cats and dogs. I've got a Bachelor of Science degree in Animal Behaviour and Welfare and have several years’ experience working in animal shelters and rescues. My passion for animals started at a very young age as I grow up on a farm with several horses, cows, cats, chickens, and dogs on our property.

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