When a kitten is about one month old, its teeth are almost all in. After that, it will continue to lose its baby teeth and grow permanent teeth. When a kitten is over one year old, you can observe the wear on its teeth to determine its age.
When asked how to tell how old a cat is, a cat stops growing at one year old. Around six years old, it will grow white whiskers around its mouth, and at seven years old, white fur will grow on its back. After ten years old, it becomes less active. Most cats enjoy playing and roughhousing, but as cats age, their coordination declines due to physical weakness, making them increasingly inactive, and eventually leading to their death.
