Runt Of The Litter – What All Owners Should Know

Litter of Terrier Mix Puppies Playing in Dog Bed Outside on Wooden Deck

This runt of litter puppy guide will teach you everything there is to know about runt dogs. Parenting a 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 the runt of the litter puppies. Let’s dive right in!

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What Is The Runt Of The Litter?

Unlike the “pick” of the litter, the healthiest and strongest pup of the litter, a runt of the litter puppy is the smallest pup of the litter. A runt puppy tends to be weaker and has the lowest chances of survival. But, why is there a runt? In her book “The Dog Breeder’s Guide To Successful Breeding And Health Management,” Dr. Margaret V, Root Kustritz, a respected board-certified veterinary theriogenologist, attributes runt dogs to “poor placentation.”

This means that the placenta is unable to 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 privilege spots near the dam, especially in crowded litters. Puppies that early on have this advantage grow up to be the strongest and grow faster than their littermates. Runts, on the other hand, are usually the last ones to eat, resulting in inadequate nutrition and growth. Does this mean that runt dogs can’t grow up to be happy, healthy, normal-sized dogs? Not really. We explain below.

New Runt Border Collie Lab Puppy outside Peering from a Basin

If the runt puppy is cared for as soon as it’s born, it will most likely go on to live a healthy life.

Runt Of The Litter Meaning

What does runt of the litter mean? While there is no clear-cut definition of exactly what a runt is, categorizing a puppy as a runt usually means the pup is the smallest of the litter and may show poor health and weakness. At the moment, there are no set parameters that qualify a puppy as a runt. The term seems to be used loosely and it’s subject to personal interpretation.

What Is Not A Runt Puppy?

Myra Savant-Harris in the book “Canine Reproduction and Whelping: A Dog Breeder’s Guide,” says that runts are not premature puppies, but that they are simply puppies who had a “poor implantation site in the uterus.” Just as large puppies are not overdue pups, but simply pups who had a great implantation site.

Runt Appearance

In terms of physical characteristics, a runt of the litter puppy has a smaller body frame than its siblings or just looks below average size/weight for its breed or age. Another common physical attribute of runts is their fragile bodies and weak bone structure.

Newborn runt puppies may also have weak suckle reflexes when the fingertip is gently placed in the mouth. Poor muscle tonality is present as well. Talk to your veterinarian about the appropriate weight gains to expect for your dog’s breed and monitor all of the puppies for signs of malnourishment.

Runt Of The Litter Personality

Runt dogs’ personalities are strongly linked to human personality just like any other dog. There is no outlying evidence that the runt of the litter will be predisposed to develop a certain personality. According to a study published in the National Center for Biotechnology Information, personality consistency in dogs is an important part of human-dog relationships.

You can expect runt puppies to have the most common personality traits of their breeds but the overall personality development of your pup and its changes over time will be shaped by the owner. Researching your runt’s dog breed personality traits is probably a good indicator of what kind of personality your runt will have. However, research suggests that, just like humans, when dogs go through significant life changes, their personality traits change.

Runt Of The Litter Puppy Health And Problems

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.

1. 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 small birth-weight puppy (runt) in the litter. A puppy should gain about 5% to 10% of its birth weight daily. Failure to gain weight is a clear sign of potential problems and should be addressed immediately.

If your runt puppy is not meeting this mark, you can hand-feed him or position him at the teat and monitor 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.

2. 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 the 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. Pro Tip: 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.

3. 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 to be normal at first, but they begin to 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 dam. 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.

4. Congenital Problems

Birth defects of congenital problems in runts may be more prominent. Why? You mustn’t have misconceptions. Well, runt puppies don’t receive the proper nutrients while 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 coming from the middle of the uterus. To avoid any further health complications, veterinary treatment should follow as soon as you notice and genetic abnormalities in runts.

5. Parasite And Infection Prone

Puppies are especially susceptible to parasites. Runts are less able to withstand a parasite load 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.

6. 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 need to be provided with an external source of warmth, especially the runt.

Similarly, hyperthermia, also known as overheating, can occur during hot climates or inappropriate supplemental heat. Higher or lower than normal temperatures for the neonate’s age should alert you to any of these two possibilities.

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 immediately begin licking each pup to mark them and show them 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 and not the runts of the litter.
  • 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 the runt up and place them down away from her. In extreme cases, the dog mother may kill the runt if she doesn’t recognize her pup as her own and give them her mother’s milk. Additionally, a dam may also reject her pup if she is sick and unable to care for them as a result. If the dam ignores or rejects a runt puppy, human intervention is necessary to help the runt of the litter survive with special care and perhaps a heating pad and proper care.
Newborn puppy dog

If the runt can suckle, you can feed it with a simple pet nurser bottle.

How To Care For A Runt Of The Litter: Step By Step

The first few weeks of a runt’s life are where 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. 

Step 1: Identify The Runt Of The Litter

The runt of a litter is usually the smallest pup, significantly underweight, unable to nurse, weak, or undeveloped, which is why you need to step in to provide the care he requires, at a lower price. Watch if the mother dog pushes away or rejects a small size puppy from the litter of puppies. If this happens, you should be concerned.

Step 2: Monitor Temperature And Keep The Runt Warm

Runts are especially prone to hypothermia and rarely to hyperthermia antibodies. Use a pediatric 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, normal body temperature rises to 97 to 100 F, and by the fourth week, body temperatures are the same as those in adults, between 99.5 and 102.5 F.

A temperature below 94 F and above 102 F can be life-threatening. Adjust the room temperature depending on the runt puppy’s age. According to VCA Hospitals, the temperature should be kept at:

  • Newborn to 7 days old – 85 to 90 F
  • 8 to 14 days old – 80 to 85 F
  • 15 to 21 days old -75 to 80 F
  • 22 to 28 days old – 70 to 75 F

We recommend using a rectal thermometer as it is the most accurate option. If the temperature is higher or lower than the specified ranges above, you should go to the vet or emergency vet hospital immediately to determine the cause.

Step 3: Check For Proper Nursing

You have to realize the runt can remain smaller than the other puppies even when fully grown. With the proper attention and care, most runt dogs catch up in real life and stop being a teacup!

Step 4: Monitor Runt Weight Daily

A runt puppy should gain no less than 5% and up to 10% of their current body weight every day during the first month, according to the puppy formula. Runt dogs generally weigh less than their littermates at birth, which is why you should check track all your puppies’ weights to measure progress. A digital scale is recommended for accurate weighing.

If the runt isn’t gaining weight, visit your veterinarian. In some cases, a runt who cannot gain any weight may be suffering from an underlying health condition. Associated with low weight is transient juvenile hypoglycemia (low blood sugar) syndrome. This condition often arises when regular feeding schedules are not maintained.

Step 5: Weaning The Runt

Once a runt puppy reaches about three and a half weeks old, it is okay to start weaning your pup from its mother’s milk. Over the next 2 to 3 weeks, blend puppy food with puppy milk substitute and offer it to the runt with bottle feeding. Let him explore and start nibbling. Gradually increase the amount of kibble and decrease the amount of milk.

At around 7 weeks, your runt should be completely weaned. They should also be eating dry puppy food and drinking water. Continue to monitor its weight during the weaning process. Call the vet if your pup is losing weight. Rushing a puppy into eating puppy food can lead to malnourishment. It’s safer to let a slow-eating puppy continue to nurse from the dam and slow the ears Ingrid process.

Step 6: Visit Your Vet

If the runt is not gaining weight, seems to be fading, shows signs of hypothermia, or doesn’t look well at all, take her to the vet immediately. If you wait too long, the puppy might die. Runts are common and can live a normal life with proper attention and nutrition. However, there might be underlying health problems only a professional can treat.

The Final Thought

And training a runt puppy shouldn’t be any 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. And never forget to feed him or her the highest-quality dog food you can find to ensure they grow as strong as they can!

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Sarah Brady

Sarah Brady is an animal lover and the proud dog-mom of a Golden Retriever named Brody and an Italian Greyhound named Jessup. Unfortunately, Jessup developed serious allergies to many different types of dog foods and ingredients when she was just a puppy. Meanwhile, Brody could eat seemingly anything and carry on as healthy as could be. Sarah spent hours of time researching and testing different foods and brands before finding something that worked for little Jessup. She wants Dog Food Care to simplify this experience for future dog-parents who face food allergy or tolerance issues of their own.