How old are Horses when their bones fully developed?

Horses' bones typically reach full development around 5 years old. However, it's important to note:

* Full development is not the same as finished growth: While the bones are fully formed, they may still grow slightly in diameter until around 7 years old.

* Individual variation: Some horses may mature slightly faster or slower depending on factors like breed, nutrition, and genetics.

* "Mature" for riding: While bones are fully developed by 5, horses aren't considered fully mature for athletic activities like riding until around 6-7 years old.

So, while a horse's bones are largely complete at 5, they are still developing and strengthening for some time after that.