Why Is My Cat So Small? 10 Reasons Plus When to See The Vet

We all wish our cats could stay cuddly and cute like a kitten forever, but if your cat is retaining her kitten-like features and small size into adulthood, you might wonder why your cat is so small. Just like humans, the body frame of a cat can vary from feline to feline. What she eats and how often she eats can have a big impact on how big a cat grows, but nutrition isn’t the only factor that determines a cat’s body size.

Most reasons for small body size in cats don’t require a trip to the vet, but a loss of appetite or sudden weight change is always a reason for a checkup.

Here’s an overview of why your cat is so small. Plus, everything you need to know about your cat’s growth cycle and ensuring she grows big and strong.

Why is my cat so small? What are the possible causes?

When it comes to the ideal weight and size of your cat, the number on the scale isn’t the only indicator to consider. Veterinarians use an assessment tool called the body condition score to determine if your cat is underweight, overweight, or just right based on her frame. Cats with a small body frame can weigh as little as five pounds and up to 20 pounds for larger breeds of cats.

So, what determines the size of your cat’s body frame and how do you know if her body size is healthy? Here’s what the experts say.

1. Poor nutrition

Cats are obligate carnivores. This means that from kittenhood and throughout their lives, cats need a protein-based diet complete with fats, vitamins, and minerals. Foods like carbohydrates and vegetables are biologically inappropriate. They don’t provide the right nutrients for optimal growth and could cause your cat to be small.

When discussing your cat’s ideal weight, ask your vet what your cat’s ideal calorie intake is. Underfeeding and malnourishment in cats can lead to serious, long-term health conditions.

2. Your cat’s eating habits

Despite the nutritious meals you plate, a cat with an eating disorder may refuse to eat. Anorexia, Pica, and fussiness are all common in the cat world and can lead to malnutrition, weight loss, and a small frame. An eating disorder could indicate an underlying health condition and shouldn’t be ignored.

Your cat’s eating habits

3. The runt of the litter

Could the small size of your cat mean she is the runt of the litter? Runts are defined by more than just their small size—they are typically underdeveloped and often look several weeks younger than their litter mates. The small size will typically persist throughout life but isn’t known to affect life expectancy.

4. Cat dwarfism

Two types of dwarfism can cause cats to be small:

Pituitary Dwarfism (congenital hyposomatotropism) is a rare condition, with only a few cases being reported in cats. Caused by a deficiency or insensitivity to growth hormones, affected cats have stunned growth of the body, teeth, and fur. Cats with pituitary dwarfism remain small throughout their lives and case studies report secondary health conditions including cysts and heart failure.

Osteochondrodysplasia is a genetic dwarfism mutation that affects cartilage development. This mutation is to blame (or thank) for the folded ears of the Scottish Fold and the short, stubby legs of the Munchkin breed. The mutation can lead to arthritis, but the folded ears and short legs are doted on in the cat community and are a common-day selective breeding choice.


5. Gender

In more species than you might expect, the female is larger than her male counterpart. This is true for cats too—up until a few months of age reports a study on the growth curve of male and female cats. The study found that female cats reach their optimal weight and size earlier, while male cats continue to grow. Another study found that although female cats have a higher fat mass, males of the same breed are typically larger in body frame.

6. Parasites

Common parasites in cats include fleas, tapeworms, ringworms, hookworms, giardia, and more. Some parasites, like fleas, are external and feed on the blood of a host. Others, like tapeworms, reside inside a cat’s digestive system and steal important nutrients from a cat. Without treatment, parasites can lead to anemia, malnutrition, and other conditions—and can result in weight loss.

7. Your cat’s breed

Like dogs, the breed of a cat plays a major role in size. The smallest domesticated cat is the pint-sized Singapura, measuring as little as nine inches in length and weighing between four and eight pounds. The largest breed of cat, for comparison, is the majestic Maine Coon. Barivel, the Italian Maine Coon holding the Guinness World Record for the longest domestic cat, measures 47 inches in length. Whether your cat is a purebred or mix, the breeds that make up her genetics will determine her frame.

Other small breeds of cats include the LaPerm, Cornish and Devon Rex, American Curl, Somali, and Burmese cats.

8. Diabetes or hyperthyroidism

Underlying health conditions, including diabetes and hyperthyroidism, can cause a change in appetite and weight loss in cats. If your cat is showing any changes in behavior or unusual weight loss or gain, it’s best to contact your vet.

Diabetes. Between 0.2 percent and one percent of cats will develop Type I or Type II diabetes in their lifetime, with Type II diabetes being most common in felines. Signs of diabetes include a sudden loss of weight despite a normal appetite and an increase in thirst and urination.

Hyperthyroidism. More common in middle-aged to older cats, hyperthyroidism is caused by the overproduction of hormones in the thyroid. In addition to weight loss, signs of the condition include poor hair coat, rapid heart rate, increased appetite or thirst, anxiety or nervousness, diarrhea or vomiting, and vocalization.

9. Malabsorption

Diarrhea and weight loss despite an increased appetite are the telltale signs of malabsorption. Caused by the disruption in the secretion of pancreatic enzymes, cats with malabsorption disease lack the ability to either digest or absorb nutrients from food.

10. Poor health

When a cat isn’t feeling well, they may lose their appetite or begin losing weight. Any changes in your cat’s eating habits, behavior, or sudden weight loss or gain should be discussed with your vet.

Poor health

Is it normal for a cat to be small?

Yes, if your cat’s body is proportional in size and scores a healthy range on the body condition score, then it is normal for your cat to be small. The small stature of your cat typically won’t affect her health or her life expectancy.

Why do some cats stay small?

Depending on breed and gender, your cat could have a small body frame and stay small throughout their adult years.

When do cats stop growing in size?

Kittens grow at an amazing rate. gaining up to 1,000 grams in the first eight weeks of life. At about six months, their rapid growth rate will begin to slow, and most cats stop growing at about nine months of age. Shortly after, around 10 to 12 months, a cat is thought to have reached maturity and is considered an adult.

cats stop growing in size

How to ensure that your cat undergoes a proper growth cycle?

Encouraging healthy growth begins in kittenhood. Keeping your cat healthy and at the right weight will continue throughout their lives.

1. Proper nutrition

Kittens have a lot of growing to do, and the right formula of food will ensure she has a proper growth cycle. Adult cat foods have different ratios of calories and nutrients than a kitten needs. So, you’ll want to look for food labeled for kittens or all-stages.

When it comes to how much and when you should feed your kitten, feeding your kitten multiple meals a day (not free feeding) is ideal. As your kitten reaches the six-month mark of slower growth, talk with your vet about her ideal weight and calorie needs.

2. Regular vet visits

If you just adopted a cat or kitten, seeing the vet is one of the first things you’ll want to do. Ensuring your cat has the right vaccines and is feeling her best will help her grow and keep her healthy. After the initial visits with your vet, adult cats should continue to see their vet at least once a year, or as recommended.

Cats are considered seniors around seven years of age. Around this time you’ll want to adjust your vet visits to every six months. If your senior cat begins to lose weight, don’t caulk it up to age and instead see your vet for the right care.


Why is my cat so small and skinny?

Your vet will perform a body condition score to determine if your cat is underweight. Cats may lose their appetite if they have dental disease, are experiencing stress, or have an underlying health condition. Malnutrition in cats can be due to a biologically inappropriate diet or parasites.

Why is my cat not growing?

A cat’s growth could be stunted by genetic mutations including dwarfism or malnutrition caused by a lack of inappropriate food or parasites. If your kitten is not gaining weight, they should see the vet immediately.

What weight is too small for a cat?

The ideal weight for cats is determined by the size of their body frame. Healthy, domesticated cats weigh between four to 20 or more pounds depending on their breed and genetic makeup.

To learn your cat’s ideal weight and calorie needs, schedule a visit with your vet. Your vet will perform the body condition score assessment, a quick and easy tool that can give the veterinarian an insight into the nutritional status of a cat.

Do runts stay small cats?

Yes, the small size of the runt of the litter will typically persist throughout life but isn’t known to affect life expectancy.

What is considered a small cat?

The smallest breed of the domesticated cat is the Singapura cat, measuring as little as nine inches in length and weighing between four and eight pounds.

What kind of cats stays small forever?

Some breeds of cats stay petite even as adults. These small breeds of cats include the Singapura, Munchkin, LaPerm, Cornish and Devon Rex, American Curl, Somali, and Burmese.


If your small cat gets a clean bill of health from the vet and scores a healthy body condition score—she is exactly the size her genetic makeup says she should be. Body frame size can vary from cat to cat and breed to breed. Getting to know your feline’s specific nutritional needs will ensure she lives a long and healthy life. If you spot a sudden change in weight, eating habits, or behavior in your cat, contact your vet for the right care.


  • Janelle Leeson

    Janelle is a cat mum to two resident adventure kitties, Lyra and Atlas, and numerous cat and kitten fosters. She has written about cats for publications such as Rover, DailyPaws, and Cat World. You can follow Janelle, her adventure cats, and adoptable fosters on Instagram at @paws_pdx or on her website at pawspdxtravels.com.