How To Tell if Your Cat Is a Runt?

How To Tell if Your Cat Is a Runt

The runt of the litter can become the runt early on in its life, or it may take some time to manifest. A runt that can get bullied by its brothers and sisters can generally have a hard time, so it’s essential to recognize the signs that your kitten is a runt.

Here is how to tell if your cat is a runt:

  1. The initial birth weight is low.
  2. The runt is not growing as fast.
  3. A changed diet can help the kitten get bigger.
  4. It doesn’t get weaned when it should.
  5. The runt will not eat as much or as often.
  6. The cat is not underweight.
  7. Compare your kitten to other kitten breeds.

I’ll take you through the significant signs and clues that your cat is a runt, as well as ways to tell even if you can’t compare your cat to the rest of the litter.

1. The Initial Birth Weight Is Low

One of the most evident signs your cat is a runt is its unusually low birth weight. Find out the weight range for your breed of kitten, and check against your kitten’s average weight.

For example, you can expect a kitten to weigh between 3-7 oz (85.04-198.4 grams) after the first week.

Keep a weight log for your kitten, and take note of any growth spurts. It may just be that your kitten has a long, rapid growth progression a few weeks after birth and still end up the same size as the rest of the litter.

Low weight may be a sign of worms, and so if you notice that the weight is not increasing, internal parasites or other infections could be to blame.

2. The Runt Is Not Growing As Fast

From the same litter, runts will not grow as quickly as other animals, particularly their brothers and sisters.

This may not be immediately apparent but it may become more evident at other developmental stages. It may be that the runt is growing at the same rate as the other kittens initially, but the introduction of solid foods sees the runt stays the same size while their siblings grow rapidly.

Check out this YouTube video about how to keep your runt kitten alive and thrive:

You’ll want to get accurate scales and weigh your kitten regularly.

Kittens grow rapidly in the first few weeks, so if you notice that your kitten is not growing at least a few ounces a week, this could be a sign that your cat is a runt.

3. A Changed Diet Can Help the Kitten Get Bigger

If the runt is not growing at the same rate as the litter, then some special consideration for the kitten may promote more growth via a different diet. Using kitten milk replacement formula mixed in with their food can provide the extra calories to make them bigger.

I recommend buying PetAg PetLac Liquid for Kittens from, as it is formulated to help newborn kittens grow faster.

You can follow a kitten feeding guide to ensure that your kitten is getting everything it needs. You can find a helpful reference on the site PawMaw which will chart the kitten’s weight against the amount of food it should be having.

Once your kitten starts eating wet food, and if you suspect that it is underweight, a substitute for kitten milk replacement formula may help. This can be mixed in with the regular wet or dry cat food to increase the calories.How To Tell if Your Cat Is a Runt

It may be helpful to feed the kitten using a feeding syringe, such as the TML Pet Nursing Bottle from, as it simulates drinking milk.

This can encourage the kittens to continue feeding for longer.

It can be challenging to use the feeding syringe properly, so get the kitten onto a table and hold it firmly by the nape of the neck. Use your other hand to squirt small amounts of the formula in and give your kitten time to eat a mouthful before trying again.

Squirting the food in from the side of the mouth can be better than shooting it directly down your kitten’s throat, preventing them from eating effectively.

If your kitten gains weight on this increased diet volume, likely, it was not a runt but underweight.

4. It Doesn’t Get Weaned When It Should

For most cats, once they get past seven or eight weeks, they should have stopped nursing from their mother. While milk is very calorically dense, solid foods will give your kitten much more energy to grow.

If your kitten is still constantly nursing after 10 weeks, you will have to try physically separating the kitten from the mother cat.

Encouraging your kitten to wean off the mother by offering a mixture of wet or dry cat food with kitten milk replacement formula to tempt them is also a successful technique you could try.

5. The Runt Will Not Eat As Much or As Often

One of the biggest giveaways that you have a runt is that your kitten will not eat its total share of food. This can be via either not finishing off a meal consistently or only having two of the three meals being offered throughout the day.

In the first few weeks, you can expect to feed your kitten every few hours.

If the kitten is with her mother, the mother cat will take care of all this feeding. Feeding an orphaned kitten can be hard work and, if not done correctly, will stunt the kitten’s growth.

6. The Cat Is Not Underweight

If your cat is not getting enough calories, then regardless of the overall potential of the cat to gain weight, it won’t be able to get there.

A quick visual check of your cat should reveal that the ribs are not visible through their coat. If you can see the hips or spine, that could also signify that the cat could stand to gain a little more weight.

An underweight cat could be a sign of other underlying issues and should be checked out with a veterinarian if you suspect other serious problems. This may include inconsistent or overly frequent urination or defecation, excessive drinking of water, or other abnormal behavior.

7. Compare Your Kitten to Other Kitten Breeds

Cat breeds are going to differ not only in size but in growth rates as well.

Some cat breeds are enormous and need rapid growth through their early years to get to such a large body size. The Maine Coon can grow up to 24 lbs (10.89 kg) for an adult male.

Other breeds like the Singapura and aptly named Munchkin cats will only grow to 5 lbs (2.27 kg). They are tiny as kittens but don’t have to grow much to get to their adult size.

Try and find friends with similar cat breeds and compare your kitten to mature cats. If there is a considerable size difference between similar breeds, this is a definite sign that your kitten is a runt.

Look at overall bone structure, head size, and paw size to compare.

Final Thoughts

Spotting the runt of the litter means looking at the slower growth rates compared to the siblings despite being on the same diet. Different breeds grow differently, so compare your kitten to similar breeds to track their growth. Look at your cat, and decide if the cat is underweight or smaller, such as in trunk size or paw size.

You’ll need to log your kitten’s growth and compare this to expected growth rates.

Make sure that your kitten is not nursing longer than two months, and mention the slow weight gain at regular appointments so they can take a look.