Why is my cat or kitten not growing?

Young animals can grow amazingly fast. When your kitten is healthy and thriving, it can seem like that cute little ball of fur is growing bigger by the day! But when you’re doing your best to care for your baby, it can be disheartening to see that they’re not gaining any weight or size.

So what could be going wrong? Why did your kitten or adult cat stop growing? Read on to discover why, and more importantly: what you can do about it.

What is “normal” growth?

First, we need to discuss at what age you can expect a healthy cat to stop growing. Of course, every cat has its own unique genes and journey through life, but there are definitely some general guidelines that can give you a clue as to how big your cat should be by the time they reach various stages.

Kittens will typically have a huge growth spurt at the start of their life, which usually lasts about 8 weeks after birth. This is a period of rapid development, where lack of growth is easy to spot and very concerning. We have listed some possible causes further down in this article, so be sure to read those.

After those first 8 weeks, a kitten will continue to grow, albeit at a more slow and steady pace, until it reaches an age of about 12 to 16 months. For many breeds, visible growth is completed around this time. But this is certainly not always the case! Bigger cats such as the Maine Coon and the Ragdoll can take multiple years to reach their full adult size!

After that first year, things are still growing on the inside. For instance, the brain will continue to develop as cats mature. But by now, the outward growth will have slowed to a point where it’s almost impossible to spot stunted growth unless you are a trained professional.

Possible causes

Home-cooked meals and raw meat diets tend to be unbalanced. The deficiency of a single nutrient can be enough to stunt growth.

If your young cat or kitten isn’t growing as expected during those first 12 months (and especially during the first 8 weeks), there are a few potential things to rule out. It might be that:

A) Lack of growth is caused by malnutrition. Your cat is not taking in enough calories and/or vital nutrients, either because they are eating less than the recommended amount, or because their food is imbalanced or of poor quality.
B) Your cat has a gut problem, which prevents the body from absorbing nutrients. Gut problems can commonly be caused by a worm infection, and will lead to symptoms such as vomiting and diarrhea, but other causes also occur.
C) There are other medical conditions that can lead to stunted growth, like pituitary dwarfism. Thankfully, these are rare.

While these are the main suspects, any ongoing illness could cause a lack of weight gain or weight loss, which is the more likely case in adult cats. However, if you have a senior cat that is thin and struggling to gain weight no matter what you feed them, they could very well have an overactive thyroid.

If you think your cat might have stopped growing, the best way to rule out possible causes is by taking it to a veterinarian.

What other symptoms might I see if my cat isn’t growing?

The main thing to look out for in kittens and young cats is a big and lasting reduction in their appetite. You might also see symptoms such as vomiting or diarrhea. However, if you have an older cat who is losing or failing to gain weight, this could very well be caused by many other conditions with different symptoms. For instance, if diabetes were the cause, you might notice an increase in their thirst and how often they pass urine. If you’ve noticed that your cat is losing weight or not gaining weight, have a check of their appetite, thirst drive, and litter tray movements before calling the vet.

What should I do?

The first thing to do is double-check that your kitten or cat is getting enough food. If you need some help, check our nutritional guidelines to get an idea of the amount of food that kittens and adult cats should be eating. Cat food also tends to come with these instructions on the packaging, but this is not always the case.

Second, if your cat has not been wormed recently, make sure that they get treatment for worms and other parasites. Don’t buy this off the internet! Instead, call your vet to get a veterinary-approved product. Kittens should usually be wormed every 2-4 weeks, depending on their age, whilst adult cats are usually wormed every 1-6 months, depending on their lifestyle. Whilst worms rarely cause symptoms in adult cats, they can overwhelm the tiny intestines of kittens and cause malnutrition.

Almost all cat food brands have a product specifically made for cats aged of 1 to 12 months. Make sure you’re not giving adult food to a young cat!

Third, if you are feeding a homemade diet, senior or adult food, or poor-quality cat food to your kitten, it would be sensible to switch to a good-quality, nutritionally complete cat food that is specifically designed for growing cats and kittens.

Finally, if all the above have been ruled out, and you still have concerns about your kitten’s lack of growth, it’s time to see a veterinarian. Cats can become very unwell very quickly when their body is not growing as it should, as this has a major effect on immune function.


Failure to grow or gain weight can be caused by a lack of food or just the wrong food. It can also be caused by gut issues, worms, and many other medical conditions. If you are concerned that your cat or kitten isn’t growing normally, the best thing to do is to contact your veterinarian. Often it is a relatively simple thing to fix, and your veterinarian will help get your furry friend back to a healthy weight in no time.

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