It takes a human approximately a grand eighteen whole years to reach adulthood. That’s eighteen years of growing pains, hormone surges and awkward periods in which features don’t quite fit into the surrounding face. However, how long does it take for our feline friends to be fully grown? When will they have reached the growth summit, and when can they be called an adult? (Note: cats also go through the awkward adolescence phase as well.)

It’s not a simple answer…

If we are wanting a quick, no-nonsense answer, then we would hazard a guess that cats are fully grown by 12 months of age. However, it is not quite as simple as this. 

There are numerous factors that this answer will be dependent on, including the breed of cat, gender, size, neutering status and diet. 

Growth plates are located near the ends of the bones of the limbs, and are responsible for the bone’s growth and lengthening. As they reach maturity, these growth plates begin to harden and close, so that the bone can no longer grow in length. This process varies between breeds and bones. For many, this occurs in cats at around 7-9 months of age. However, in some, it can occur as late as 18-20 months. Skeletal maturation is therefore considered to be complete at around 18 months of age. 

Milestones for growing cats 

Newborn to 6 months

This is the most rapid growth stage, and the most important stage for socialisation. Baby teeth will be replaced by adult teeth, and they will no longer look like a ‘baby kitten.’ 

6-12 months

They will have started going through sexual maturation, and growth will slow down at this stage. It is also their adolescence, or teenage years, so you may find that they are more rebellious and brave in these months. They may also look a bit awkward and lanky, which is of course Mother Nature’s requirement of every teenager in existence. At this stage, your veterinarian will recommend spaying or neutering to prevent any surprise litters!

12 -24 months 

Now that they have reached adulthood, you may start to see their behaviour shifting. Most breeds will do the last of their growing in this time, ‘filling out’ that little bit more, and having the look of an adult cat. They will also socially and behaviourally reach maturity. 

What if I have a large-breed cat? 

Maine Coones can weigh up to 20 pounds, coming in remarkably bigger than most of the other cat breeds. Unsurprisingly, they reach full growth at a later stage of life, and are only considered to be fully grown at 4-5 years of age.

The ragdoll is another breed that takes longer to reach maturity due to their size, and have growth potential up until 4 years of age, often coming in spurts. They, on average, weigh approximately 15 pounds. 

When should I switch to adult cat food? 

For most cats, switching to adult cat food is appropriate at 12 months of age. However, for the Maine Coon that may be struggling to retain its body weight, keeping them on kitten food for longer may be required. Alternatively, if a 8-10 month old indoor kitten is overweight, then it may be appropriate to put them onto an adult food earlier. 

As always, it is best to have a chat with your veterinarian at their routine health checks to discuss what is best for your pet. As for many other components of medicine and animal care, there is no ‘one-size-fits-all’ approach, and tailoring your care to best fit the needs of your animal will result in a far better outcome over the course of their life. 

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