Runt Kitten: Life Expectancy, Feeding, Care, & Health Issues

Kittens at birth are very small, they weigh about 3.5 ounces. As they grow, kittens gain up to 10 grams per day till they are weaned off at about 8 weeks with a weight of about 2 pounds. The essence of this background history is to give you insight into how kittens should look at certain growth phases.

If your kitten has not shown any significant increase in growth after a few weeks of birth compared to its littermates, then such a kitten can be called a runt. This is not a condition to panic about, runt is a condition that requires special attention. This article will guide you on how to manage and care for runt kittens.

What is a Runt Kitten?

A runt kitten, also known as a weakling, is a kitten in a litter that is significantly smaller or weaker than the others. Runt kittens often have a visible size difference from their littermates. They have less muscle mass, thinner bones, and feel lighter when picked up. This can happen for a few different reasons:

– Smaller size: Runts are usually at least 25% smaller than the biggest kitten in the litter. Their low birth weight makes them weaker and more vulnerable.

– Prematurity: If a kitten is born earlier than the rest, before fully developing, it will be smaller and weaker. This early birth can stunt its growth.

– Illness: Kittens that get sick in the womb may have developmental issues and be born smaller. Illnesses can also cause low weight.

– Genetics: Some cat breeds are just naturally smaller. A purebred kitten may be a runt compared to mixed-breed littermates.

– Malnourishment: An underfed mother cat can give birth to weaker, smaller kittens. Lack of nutrition inhibits their growth.

– Litter size: In large litters, competition for food can prevent the smallest from getting enough nutrition to thrive.

Runt kittens may develop slower, act shy, and get bullied or pushed out by larger kittens. While runts may face additional health challenges early on, with proper care and nutrition, many runt kittens can live into their late teens like other cats.

Average Lifespan of Runt Cats

Runt kittens can have normal lifespans and live just as long as regular-sized cats if they are otherwise healthy. On average, house cats typically live between 12 – 15 years, the runt kittens can live as long as this too. The most important factor impacting a runt kitten’s lifespan is their overall health.

Runts that thrive and have no underlying medical conditions can live full, normal lifespans. However, runts are prone to health issues like respiratory infections, heart defects, and low blood sugar at birth. If these problems persist or develop later in life, they can sadly shorten their lifespan.

Providing runt kittens with appropriate veterinary care, nutrition, vaccination, exercise, and socialization gives them the best chance to live normally and longer. With a nurturing environment and proactive health management, runt cats can enjoy similar lifespans to average-sized cats.

Signs Your Kitten is a Runt

Runt kittens often exhibit some telltale signs that differentiate them from the rest of the litter. Here are the most common traits of a runt kitten:

– Smaller Size: Runts are significantly smaller than the other kittens, sometimes less than half the size. They have trouble competing with their larger litter-mates for food and warmth.

– Trouble Nursing: Due to their small size, runts may have difficulty nursing from their mother. They can get pushed away by larger kittens and struggle to get adequate milk. Runts may make high-pitched cries signaling they are hungry.

– Slow Growth: Runt kittens grow at a slower rate than the rest of the litter. They reach developmental milestones like walking, teething, and opening their eyes later than their litter-mates. Their weight gain is also much slower in the initial weeks.

Keeping an eye out for these signs can help identify runts that may need extra care and attention.

Feeding a Runt Cat

Runt kittens often need specialized feeding plans to help them gain weight and catch up developmentally. Since they are smaller, they burn calories faster and need more frequent feedings than the average kitten. Here are some tips for feeding a runt cat:

1) Bottle Feeding: Runt kittens may need supplementary bottle feeding in addition to nursing from their mother. Bottle feeding allows you to monitor milk intake and ensure the kitten gets adequate nutrition. Use kitten milk replacement formula and feed every 2-3 hours.

2) High-Calorie Diet: Feed a high-calorie kitten food or formula to help your runt kitten gain weight. Look for foods with higher fat and protein content. You can also supplement with nutritional gel or paste formulated for underweight cats.

3) Frequent Small Meals: Offer smaller portions but feed more frequently, about 4-6 times per day. Runts have tiny stomachs so they can only eat a little bit at a time. Breaking meals into smaller sizes prevents overfilling their tiny tummies. 

4) Weigh Often: Weigh your runt kitten daily to ensure they are gaining weight appropriately. Record weights to monitor progress. Kittens should gain about 4-8 oz per week. If not, adjust feedings and consult a vet.

With extra calories and frequent feedings, your runt kitten can grow into a healthy, thriving cat. Be sure to monitor their development and provide vet care as needed. With time and care, runt kittens can live long, full lives.

Related: Dry Food for Kittens: Is 2 Months Too Young?

Health Issues in Runt Cats

Unfortunately, runt kittens are more prone to health problems that can impact their lifespan. Here are some of the common health issues seen in runts:

1) Respiratory infections: Runts often have underdeveloped lungs and respiratory systems, making them more susceptible to infections like feline herpesvirus and calicivirus. These upper respiratory infections can cause sneezing, runny eyes and nose, lethargy, and poor appetite. If not treated promptly, respiratory infections can be life-threatening in runts.

2) Hypoglycemia: Runts can be prone to low blood sugar (hypoglycemia) because of their small size and inability to regulate glucose levels effectively. Signs include weakness, trembling, and seizures. Untreated hypoglycemia can lead to coma and death in severe cases. Regular feeding of high-calorie supplements can help prevent this.

3) Heart defects: Some runts are born with underdeveloped hearts or congenital heart defects. This can put additional strain on their body and lead to problems like heart murmurs, irregular heartbeat, and heart failure over time.

4) Weak immune system: In general, runts have weaker immune function compared to the average kitten. Their bodies are less capable of fighting off viruses, bacteria, and parasites. Even common illnesses can become severe and lead to a shorter lifespan.

5) Failure to thrive: Runts are at risk of failing to grow and gain weight at the normal developmental rate. This makes them perpetually smaller and weaker than typical cats. Lack of thriving can be life-limiting if runts don’t receive specialized nutritional and medical care.

Because of these potential health problems, runts have a reputation for having shorter lifespans than normal-sized cats. However, with attentive veterinary care, preventative treatment, proper nutrition, and a loving home, many runts can live long and healthy lives.

Caring for a Runt Kitten

Runt kittens require some extra care and attention to help them thrive. As the smallest in the litter, they may need a little assistance in their first weeks of life. Here are some tips for caring for a runt kitten:

– Extra supervision: Keep a close eye on the runt to make sure it is nursing properly and gaining weight. Check for dehydration by pinching the skin over the back of the neck. It should spring back immediately when released.

– Assisting with nursing: Runts may have trouble competing with larger littermates for nursing time. Place the runt at the best milk supply when the mother is feeding. Supplement with bottle feeding if needed.

– Providing nutrition: Ensure the runt is getting adequate nutrition to grow. Weigh daily to monitor weight gain. Bottle feed kitten formula if the kitten is struggling to nurse. Provide wet food as soon as the kitten can eat on its own to encourage weight gain.

With some extra TLC in those critical first few weeks, most runts can go on to be healthy, normal-sized cats. Keep a close watch to ensure the kitten is thriving. If you have any concerns about its health or development, consult your veterinarian. With time and care, that tiny kitten can grow into a wonderful pet.


Runt kittens require special care and attention to ensure they grow properly and live long. I hope this article is helpful enough for every runt kitten owner.

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.

error: Content is protected !!