Runt of The Litter: Meaning, Pros & Cons, Personality, Development - Are Runt Puppies Bad & Stay Small?

Canine Bible is reader-supported. We receive affiliate commissions via some of our links. This doesn’t affect rankings. Learn more.

This content was reviewed and fact-checked by veterinarian Dr. Sandra Tashkovska, DVM.

This runt of the litter puppy guide will teach you everything there is to know about runt dogs. Parenting a runt puppy is no walk in the park. The term runt puppy is often coined for the weakest and smallest pup of the litter. So, should you pick the runt of the litter? Will a runt puppy grow to normal size? Are there any health risks associated with runt dogs? Can they survive and thrive as well as other puppies? We’ve researched and answered every possible question and concern about runt of the littler puppies. Let’s dive right in!

What Is The Runt of The Litter?

The “runt of the litter” refers to the smallest and often weakest pup. A runt puppy tends to be weaker and has the lowest chances of survival.

In her book “The Dog Breeder’s Guide to Successful Breeding and Health Management,” Dr. Margaret V. Root Kustritz, a respected board-certified veterinarian theriogenologist, attributes runt dogs to “poor placentation.” This means that the placenta cannot supply adequate oxygen and nutrients to the runt from the mother’s bloodstream. This placenta malfunction consequently hinders the runts’ growth and chances of thriving.

Another way to understand why runt puppies happen is natural selection (survival of the fittest). Litters compete for milk and privileged spots near the dam, especially in crowded litters. Puppies with this advantage early on become the strongest and grow faster than their littermates. Conversely, runts are usually the last to eat, resulting in inadequate nutrition and growth.

Runt of The Litter Meaning

What does runt of the litter mean?

The term “runt” doesn’t have a precise meaning and is more of a colloquial term. Categorizing a puppy as a runt usually means the pup is the smallest of the litter and may exhibit signs of poor health and weakness. Currently, there are no set parameters that define a puppy as a runt. The term seems to be used loosely and is subject to personal interpretation.

Myra Savant-Harris, in her book ‘Canine Reproduction and Whelping: A Dog Breeder’s Guide,’ states that runts are not premature puppies; instead, they are simply puppies who had a ‘poor implantation site in the uterus.’ Similarly, large puppies are not overdue puppies but pups with a great implantation site.

Runt of The Litter Personality

Like any other dog, runt dogs’ personalities are strongly linked to human personality. There is no outlying evidence that the runt of the litter will be predisposed to develop a specific personality.

According to a study published in the National Center for Biotechnology Information, personality consistency in dogs is an important aspect of human-dog relationships. You can expect runt puppies to have the most common personality traits of their breeds, but the owner will shape the overall personality development of your pup and its changes over time.

However, there are some perceived personality traits associated with runts:

Resilience

Due to their initial size and health disadvantages, runts may develop a resilient nature. They might have to work harder to compete with their siblings for food and attention, which can lead to a more determined or tenacious personality.

Submissive

In some cases, runts may exhibit more submissive personalities within the dynamics of their littermates. This could result from being smaller and less dominant in the early stages of development.

Independence

Sometimes, runts may become more independent, learning to fend for themselves early.

Affectionate and Sociable

Some runts, especially those that receive extra care and attention from humans, may develop affectionate and sociable personalities. They might become more bonded to humans due to this additional interaction.

Intelligence and Resourcefulness

There is an anecdotal belief that runts, having to navigate their initial disadvantages, may develop a keen intelligence and resourcefulness.

Researching your runt’s dog breed personality traits is probably a good indicator of what kind of personality your runt will have. Research suggests that, just like humans, when dogs go through significant life changes, their personality traits change. Therefore, while runts may sometimes display these traits, each animal is unique, and their personality will develop based on a multitude of factors beyond just their size at birth.

Runt of The Litter Appearance

Regarding physical characteristics, a runt of the litter puppy typically has a smaller body frame than its siblings, or it may appear below the average size or weight for its breed and age. Another common physical attribute of runts is their fragile bodies and weak bone structure.

Newborn runt puppies may also exhibit weak suckle reflexes when a fingertip is gently placed in their mouths. Poor muscle tonality is another characteristic. It’s important to talk to your veterinarian about the appropriate weight gains to expect for your dog’s breed and to monitor all puppies for signs of malnourishment.

Runt of The Litter Puppy Health Risks

It can be tough being a runt puppy. There are several runt dog health issues associated with runt puppies. Here is a list of the most common run health problems.

Low Birth Weight: It’s important to weigh each puppy when they are born. Weighing each puppy in the litter will help you identify the one with a small birth weight, commonly known as the runt, in the litter. A puppy should gain about 5% to 10% of its birth weight daily. Failure to gain weight is a clear early sign of potential problems and should be addressed immediately. If your runt puppy is not meeting this mark, you can hand-feed them or position them at the teat and monitor their milk intake. According to the AKC, low birth weight pups have an 81% chance of death in the first 48 hours. A study on canine neonatal mortality by Acta Veterinaria Scandinavica showed that puppies with a small birth weight have a very high mortality rate.
Colostrum Milk Deficiency: Colostrum is a special milk produced by the dam during the first 24 to 48 hours after birth. Colostrum has powerful life-supporting immune and growth factors that ensure the health and vitality of newborn puppies. If the runt fails to drink this milk, its immune system will severely weaken, making the runt more prone to illness and infections. Human intervention may be necessary to help the runt get proper amounts of Colostrum. You may need to buy a milk replacer containing Colostrum. Runts can’t always latch on to suckle after birth as they are weak. It’s a good idea to let another puppy nurse first. Once the milk has started to flow in the dam’s mammary glands, move the puppy and put the runt in its place so he can nurse more easily.
Fading Puppy Syndrome: It can be caused by several factors, including low birth weight, poor mothering, infection, environmental impact, or congenital defects. “Faders” may appear normal initially, but they deteriorate slowly. The litter’s runt is particularly vulnerable to this condition due to its immature and weaker immune system. Fader puppies usually fail to gain weight, vomit, are lethargic, and often repeatedly cry in a high-pitched tone. Sometimes, they isolate themselves in corners away from their littermates and dams. Neonatal mortality in puppies varies from 12% to 36%, which is why human intervention can save a fading puppy if the condition is recognized early on.
Congenital Problems: Birth defects or congenital problems in runts may be more prominent. Why? Well, runt puppies don’t receive the proper nutrients in the uterus. This affects adequate development, resulting in genetic defects or being less fit than the other puppies during birth.
Some defects include cleft palates, cardiovascular deformities, and dwarfism. To avoid further health complications, veterinary treatment should follow as soon as you notice any genetic abnormalities in runts.
Parasite and Infection-Prone: Puppies are especially susceptible to parasites. Runts are less able to withstand parasites such as hookworms and roundworms. These worms use the puppy’s body as a host and can cause stunted growth and weight loss, which can be fatal in a runt.
Hypothermia and hyperthermia: Did you know hypothermia is a primary or contributing cause of many newborn puppy deaths? Puppies are poikilothermic, meaning they cannot regulate their body temperature for a week or two after birth. A runt of the litter should stay close to its mother. However, if the mother leaves her puppies alone or rejects them, they must be provided with an external source of warmth, especially the runt. Similarly, hyperthermia (overheating) or inappropriate supplemental heat can occur during hot climates. Higher or lower-than-normal temperatures for the neonate’s age should alert you to these two possibilities.

Runt of The Litter Pros And Cons

Pros

Runts often remain slightly smaller than their littermates, which can be a plus depending on an owner’s space and lifestyle
Dog breeders may sell the runt at a lower price
For families with children, raising a runt can teach valuable lessons about compassion, responsibility, and the rewards of caring for a weaker or smaller being
Runts, having faced challenges early on, can sometimes develop unique and endearing personality traits
Runts tend to be more adaptable to different environments and situations
Runts of litters are generally healthy but must monitor their weight and ensure proper nutrition
Helping runts thrive and get stronger is a rewarding experience
Better physical and mental health
Unconditional love and devotion

Cons

It’s harder for runts to nurse from their mom
Higher mortality rate than siblings
Can be rejected by their mothers
More prone to health issues
May pose a financial burden
They may face developmental challenges
Require extra time and care

Is It Bad To Get The Runt of The Litter?

Getting a runt puppy can be harmful only if the runt’s health is severely compromised. Also, if you are new to puppy parenting, a runt puppy may not be your best choice, as some may require special care. Runt can live just as well as any other puppy, provided they are looked after.

If the runt of the litter is in good health, you shouldn’t have to worry about the cons of raising a runt dog.

Runt Puppy Development

Does a runt puppy develop normally?

Several factors can cause stunted development in runts, from intestinal worm infections to malnourishment or genetics. While most runts can grow normally, some may fail to develop quickly due to congenital defects such as macroglossia, which involves incomplete or abnormal tongue development. Puppies who receive too much or too little calcium during their formative stages may develop abnormal bone growth rates. Poor placentation can lead to low birth weight in newborn puppies, resulting in several problems, including poor development.

According to WebMD, the most common reason a puppy’s growth becomes stunted is infection with hookworms or roundworms. Most puppies are born with worms, so deworming them is crucial. Worms can consume enough calories from the puppy to slow their growth and hinder proper development.

If you discover that your puppies are infected with worms, consider using Safe-Guard Canine Dewormer. It’s effective against most types of worms that affect dogs. If you are concerned about the development of your runt dog, the Kennel Club in the UK divides the puppy development process into ten stages. You can follow these stages to track if your runt pup is developing normally.

Do Runts Stay Small?

Whether runts stay small can vary widely depending on several factors, including their breed, underlying health issues, genetics and nutrition. Runt puppies don’t always stay small. Runts can and often will grow to match the size of their siblings. However, the runt can remain smaller than the other puppies even when fully grown. Each case is unique, and good care and nutrition can often positively influence a runt’s future size.

Are Runts of The Litter More Aggressive?

The runt of the litter dogs are not predisposed to have a more aggressive temperament or disposition. Aggressive dog behavior is mainly due to external factors such as socialization, nurturing, neglect, or improper training. A year-long survey of dog owners who use confrontational or aversive methods to train aggressive pets found that these dogs will continue to be aggressive unless training techniques are modified.

Will The Dam Reject The Runt of The Litter?

Yes, a mother dog can reject the runt of the litter and turn on her runt. This rejection may hasten its death.

How do you know when dog mothers reject the runt? The most common signs to look out for are:

Absence of licking: It usually happens right after a litter is born. A dam will begin licking each pup to mark them and show she cares about their welfare.
Too weak to survive: Mothers know when a runt is too weak to survive, and they will refrain from giving her resources to the pup, ensuring only the strongest and healthy ones survive.
Sick runt: A dam may reject a runt with health problems such as a viral or bacterial infection, congenital birth defects, or any other contagious diseases that may jeopardize the rest of the litter.
Separate the runt: The mother may pick it up and place it away from her.

If the dam ignores or rejects a runt puppy, human intervention is necessary to help the runt of the litter survive.

In extreme cases, the dog mother may kill the runt if she doesn’t recognize her pup as her own. A dam may also reject her pup if she is sick and unable to care for them.

Most dog moms abandon their runts. Watch this special mama taking care of her runt puppy.

How to Pick a Runt Puppy

Ask the owner or breeder lots of questionsAsk about the vaccines the puppy has received. Have they vomited or had diarrhea? Are the runt’s parents certified? Have any of the littermates been sick or received medication? Do they have health certificates?

Survey physical appearanceA healthy puppy should be able to move and nurse effectively. If a puppy is static, except when sleeping, this could be a warning sign. Inspecting the puppy for clean ears, gums, and teeth is important. Check for the absence of discharge around the head, nose, genitals, or eyes. Make sure the coat is shiny, and also look for any bumps, bald spots, or sores.

Spend time with the runt’s motherA weak mother is likely to produce a weaker litter. Therefore, it’s crucial to inquire about the dam’s health history.

Health recordsRequest the deworming records, vaccination history, and medical history of the runt. Additionally, obtain the same information for the mother to rule out any possible genetic health conditions.

Observe the puppies in actionTake this opportunity to assess the personality of each puppy in the litter. You may find that some puppies are very energetic while others are more cuddly, submissive, dominant, or playful. It’s important to choose a puppy whose temperament aligns with your personality, lifestyle, and family dynamics.

Schedule time alone with your chosen pupAssess how compatible you and the puppy are. Try calling the runt puppy and observe his responsiveness and ability to adapt to a new situation. After ruling out any health issues and choosing this puppy, it’s important to plan to keep your new pup at home until he receives all his shots and vaccines, typically until about 12-16 weeks old.

How To Care For A Runt of The Litter: Step by Step

The first few weeks of a runt’s life is when it needs you the most. This step-by-step guide shows you how to care for a runt puppy so your little furry friend can thrive and live a healthy life.

The runt is usually the smallest pup, significantly underweight, and may be unable to nurse, displaying weakness or underdevelopment. This situation necessitates your intervention to provide the care he requires. Observe whether the mother dog pushes away or rejects a particular puppy. If this happens, it should be a cause for concern.

Runts are particularly prone to hypothermia and, less commonly, hyperthermia. Use a pediatric digital thermometer to take the puppy’s temperature rectally. In the first week of life, the normal body temperature in newborn puppies is 95 to 98°F. In the second and third week, it rises to 97 to 100°F. By the fourth week, body temperatures reach adult levels, between 99.5 and 102.5°F.

A temperature below 94°F or above 102°F can be life-threatening. Therefore, adjust the room temperature according to the runt puppy’s age. As recommended by VCA Hospitals, the temperature should be maintained at:

Newborn to 7 days old – 85º to 90ºF
8 to 14 days old – 80º to 85ºF
15 to 21 days old – 75º to 80ºF
22 to 28 days old – 70º to 75ºF

We recommend using a rectal thermometer, as it is the most accurate option. If the temperature falls outside the specified ranges above, seek immediate veterinary attention to determine the cause. Always consult your veterinarian if you have concerns or questions about your puppy’s health.

It’s your responsibility to help a runt puppy gain weight. If the runt is unable to nurse, gently pick it up and bring it to the dam’s teat. Should the puppy be unable to suckle or if the mother rejects it, you must begin hand-feeding it yourself.

There are three options when it comes to feeding a runt puppy.

Runts require strict attention to their hygiene for optimal health and development. Always wear new surgical gloves when handling the runt. Sterilize bottles and nipples in boiling water between uses.

Milk from the mother: Wear surgical gloves and gently squeeze milk from the mother’s teat into a sterile cup. Then, transfer the milk to a pet nurse bottle from which the runt can suckle.
Puppy milk substitute: If obtaining milk from the dam is impossible, or if the puppy is rejected by its mother, consult your veterinarian for the best puppy milk substitutes.
Tube feed the runt: If your runt pup is too weak to suckle or has congenital impediments that prevent it from nursing, learn how to tube feed the runt. Have your veterinarian demonstrate and guide you through the procedure. Incorrect tube feeding can accidentally push food into the puppy’s lungs or cause other serious injuries.

It’s critical to feed Colostrum within the first 24 hours after birth. Colostrum is a vital nutrient-rich milk produced by the dam, carrying antibodies to fortify the immune system. Milk powder enriched with Colostrum is a great alternative for feeding a runt puppy. We recommend using a nursing kit for hand-feeding. Remember, puppies generally need to nurse at least every two to three hours, though this varies as they grow.

Newborn puppies require stimulation to urinate and defecate properly. Normally, the mother licks their genital area to facilitate this process, but if you are caring for a neglected runt of the litter, you will need to take on this role. After feeding the runt, use a lukewarm cotton ball or soft cloth to rub the puppy’s genital area and anus gently. This stimulation should prompt the runt to urinate or defecate. Be sure to clean up any mess and thoroughly wash your hands afterward.

A runt puppy should gain no less than 5% and up to 10% of their current body weight daily during the first month. Runt dogs typically weigh about 25% less than their littermates at birth, so it is important to check and track the weights of all your puppies to measure their progress. A digital scale is recommended for more accurate weighing.

If the runt isn’t gaining weight, it is advisable to visit your veterinarian. Sometimes, a runt that cannot gain weight may suffer from an underlying health condition. One associated issue is transient juvenile hypoglycemia (low blood sugar) syndrome, which often arises when regular feeding schedules are not maintained.

Other reasons that your runt isn’t putting on weight may include:

Inadequate food intake
Parasites
Dental problems
Nutrient deficiencies
Digestive issues
Food allergies
Diabetes

Once a runt puppy reaches about three and a half weeks old, it’s safe to begin weaning it off its mother’s milk. Over the next 2 to 3 weeks, gradually blend puppy food with puppy milk substitute and offer it to the runt. Allow him to explore and start nibbling. Gradually increase the amount of kibble and decrease the amount of milk substitute.

By around 7 weeks of age, your runt should be weaned entirely, eating dry puppy food, and drinking water. Please continue to monitor its weight throughout the weaning process. If your puppy is losing weight, call the veterinarian.

Rushing a puppy into eating solid food can lead to malnourishment. It’s safer to allow a slow-eating puppy to continue nursing from the dam and to slow the weaning process accordingly.

If the runt is not gaining weight, appears to be fading, shows signs of hypothermia, or doesn’t seem well, take her to the veterinarian immediately. A runt that doesn’t respond well to human nursing may require special treatment. Delaying veterinary care could be fatal. Runts are common and can lead normal lives with proper attention and nutrition. However, they may have underlying health problems that only a professional can diagnose and treat. Regarding bathing a runt puppy, when is the right time? For guidance on this, read our ‘bathing puppy guide.’

How To Fatten Up A Runt Puppy?

Runt puppy not gaining weight? Runt puppies often have weak glands, and some may lack the energy to feed as frequently or struggle to latch on to suckle. In such cases, you must manually position the puppy near the dam’s mammary glands to facilitate easier nursing. If this approach is ineffective, consider supplementing with extra food while the puppy is still nursing.

If the runt is too young for dog food, you’ll need to obtain a special formula prescribed by your veterinarian and bottle-feed him as an additional source of nutrition. Once the puppy is old enough for dog food, introduce it, but feed the runt separately to prevent stronger puppies from stealing the food. Another option is to purchase a high-calorie nutritional gel designed for animals recovering from illness or surgery. This gel can also benefit pregnant animals and puppies struggling to get nutrients and calories.

Do not prevent the runt from drinking the mother’s milk whenever possible. Monitoring the puppy’s weight daily is essential to ensure it gains weight. For the best course of action, always consult your veterinarian for advice.

Keeping The Runt In a Separate Whelp Box For Safety

Keeping the runt in a separate whelping box might not always seem ideal, but it can be a necessary precaution. Newborn runts are often fragile, with weak bones, and a separate whelping box can help eliminate the risk of the runt being accidentally crushed by the dam or other puppies. Runts are also more prone to parasites and infectious diseases. Therefore, separating them from the litter might be wise to prevent a possible outbreak.

When selecting a runt of the litter puppy, it’s advisable to avoid puppies from a dam’s first litter. Ideally, you should choose a puppy from the dam’s third litter with the same sire. This increases the likelihood that the dam has previously conceived healthy pups with the same father, indicating a proven track record of healthy litters.

Breeding Runt of The Litter

You might think runts are unsuitable for breeding, but this assumption is often misplaced. A runt deemed perfectly healthy by a veterinarian and has passed standard health examinations can indeed have its puppies. The same applies to a pairing of two runts.

It’s important to remember that although runts may have a slow start, they often catch up and grow like normal dogs once properly nursed and weaned. However, a runt that does not grow to a standard and healthy size should be treated accordingly. Breeding unhealthy runts is considered unethical and should be avoided.

Is A Runt Puppy Cheaper?

Given the risks associated with runt dogs, some dog breeders might offer the runt at a lower price. While runts can be slower to develop than their littermates, a healthy runt may still be sold at the same price as the other puppies by the breeder. Many runts catch up quickly and grow the same size as their siblings, sometimes even larger. However, beware of unethical breeders. Some may attempt to market runts as ‘teacup’ or ‘micro’ puppies and charge higher-than-normal prices, exploiting the runt’s smaller size for profit.

Frequently Asked Questions

No, if a litter’s runt reaches six to eight weeks, it will probably survive and grow close to full size or even larger than its siblings.

Training a runt puppy shouldn’t be harder than training a typical puppy. It’s about consistency, patience, and positive reinforcement. The goal is to instill good habits and build a loving bond with your runt.

If a runt is rejected by her mother or you decide to keep her separate from the litter for safety reasons, it’s essential to ensure she stays warm. Set the room temperature as specified earlier, and consider placing a heating pad designed for dogs in the whelping box. Position the heating pad on only one side of the box so the runt can move away if it gets too hot.

Never place the runt directly on the heating pad. Instead, use a towel or cover between the heating pad and the puppy. This extra layer will help prevent thermal burns or overheating. Closely monitor the runt’s temperature; open-mouth panting indicates she is too hot. Alternatively, you can gently hug and cuddle the runt against your chest under your clothing to warm her up.

Runt are weaker at birth and sometimes present health problems due to their small size.

There are several misconceptions and myths about runt dogs. These include runts, which are puppies positioned in the middle of the uterus. Runts are puppies that come from the eggs that were fertilized last; the puppy conceived last will be the runt.

Should I Pick the Runt of the Litter?

Is picking the smallest pup, the runt, a bad choice? The answer is both yes and no. If you are considering getting a runt, it’s crucial to know the pup’s health status and observe its behavior when interacting with its dam and littermates.

Picking a runt puppy is acceptable if the puppy is the smallest in the litter but otherwise healthy. However, choosing an abnormally small runt that shows signs of infections or presents congenital deformities at birth is risky. These conditions can be indicators of future health complications. Not every runt puppy will thrive; some may require more care and attention than others. Responsible dog breeders should provide a complete medical history for the runt. Ensure that a veterinarian thoroughly checks the runt for serious health conditions.

Relying solely on your intuition and emotions when selecting a runt is not advisable. Being fully informed about the health status of your prospective puppy is vital for responsible care and ownership.

Like It? Subscribe & Share!

Sources

Canine Bible uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process and product review methodology to learn more about how we fact-check, test products, and keep our content accurate, reliable, and trustworthy.

Kustritz, M. V. R. (2006). The Dog Breeder’s Guide to Successful Breeding and Health Management. Elsevier Health Sciences.
Fratkin, J. L., Sinn, D. L., Patall, E. A., & Gosling, S. D. (2013). Personality Consistency in Dogs: A Meta-Analysis.
Michigan State University
Greer, D. M. (2022). How to detect and manage risk factors in newborn puppies.
Indrebø, A., Trangerud, C., & Moe, L. (2007). Canine neonatal mortality in four large breeds. Acta Veterinaria Scandinavica, 49(S1).
Freshman, J. L. (2005, November 1). Causes of fading puppy and kitten syndrome. dvm360.
Williams, K., & Downing, R. (n.d.). Feeding orphaned puppies. VCA Animal Hospitals.
DMV360
PetCoach. (n.d.). Weaning puppies.

Canine Bible

Editorial Team at Canine Bible | + posts

Canine Bible authorship represents the unified voice of our entire editorial team and our in-house veterinarians rather than a single author. Each article, blog post, and review published under the Canine Bible name undergoes a rigorous review process, involving all team members to guarantee accuracy and up-to-date in accordance with the latest veterinarian research. This collaborative effort is an integral part of our editorial process and aligns with our four pillars of content creation. This approach ensures our content is backed by expert knowledge and factual information, offering our readers reliable, actionable, and trustworthy content.

Runt of The Litter: Meaning, Pros & Cons, Personality, Development – Are Runt Puppies Bad & Stay Small?

What Is The Runt of The Litter?

Runt of The Litter Meaning