The horse has a life cycle that can be broken down into four very distinct phases. Beginning at birth, the horse evolves into adolescence, adulthood and finally old age.
Horses are born after a gestation period of 11 months, and for the next year are called foals. In the first year, horses grow rapidly and will reach 90 per cent of their adult height and 80 per cent of their adult weight.
The yearling has almost grown into its long legs, and its body frame has filled out. With each growth spurt, its hind is often two to three inches taller than its withers (the curved part right below the neck).
Most two-year-old horses have reached their adult height and weight. In most cases, growth plates (epiphyses) located in the bones of the legs have closed and the horse can now be ridden.
A horse finally reached adulthood at the age of four. Females are now referred to as mares, and males as stallions or geldings.
The Geriatric Horse
By their late teens or early twenties, horses begin to show the signs of ageing. Their backs begin to sag, and many develop age-related disorders such as kidney and liver disease. In the wild, these conditions contribute to rapid deterioration and death, but with proper care, horses can live into their mid thirties.