You may be familiar with how dogs age as compared to humans, but what about the horse? In the first year of life, the foal grows more rapidly than the human child. From birth until 3 years, the horse ages approximately 6.5 years for every human year. In his third year of life, the horse's age slows to about 5 years for every human year. The 3-year-old horse is the rough equivalent of an 18-year-old human. From 4 years on, the horse ages only about 2.5 years for each human year. A 22-year-old horse is approximately 65-years-old in human terms. A horse that lives to the ripe old age of 36 is the equivalent of a 100-year-old person.

All age equivalents in the charts are approximate, and just as with humans, some animals age better than others.

Horse	Human
1 year	6.5 years
2 years	13 years
3 years	18 years
4 years	20.5 years
10 years	35.5 years
17 years	53 years
20 years	60.5 years
24 years	70.5 years
30 years	85.5 years
36 years	100.5 years

Information courtesy of The Foaling Primer: A Month-by-Month Guide to Raising A Healthy Foal.