This is a common question since so many of our animals are rescued or adopted from shelters with little known of their history. It can be difficult to gauge an adult animal’s age based on physical appearance alone. Adding the animal’s opinion can help give a more accurate picture in some cases.
Animals measure time in different ways. Some understand the concepts of month, year and so on, and measure time quite accurately in that framework. Others don’t feel the need to assign labels to time and have devised their own way of tracking it. A small percentage have trouble with the concept or never learned it to begin with and just guess.
Many animals know their age because their people tell them. One adopted dog was estimated by the shelter to be “at least 3” and his new parents wondered if that was accurate. When I asked the dog he said he was 5 and in fact just had a birthday that June. How did he know this? The dog said it’s easy, his age and birthday are written down in his chart at the vet’s office where his previous family took him for regular checkups. At each appointment the vet would scan the chart and mention the dog’s age and birthday.
It’s easier for animals to keep track of their age when they’re younger because the memories are fresher. One young dog I spoke with felt he was born in springtime because that was his earliest memory. He could remember being with his mom and littermates; he saw flowers emerging from the bare ground, the air was chilly and people were talking about how it would be warming up soon.
Some animals think of time passing relative to the length of their life. For example, a cat didn’t know her age but could say confidently that she’s been with her current family twice as long as with her previous family. Since she was adopted 4 years ago we can assume she’s 6 now. She gave other clues that helped back it up, such as that the family adopted a kitten halfway through the time she’s lived with them. Piecing the clues together gave a reliable timeline.
Some animals lie about their age! Dogs are pretty honest but I’ve found cats have a tendency to intentionally shave off a few years. Horses are often reluctant to tell their age; they don’t want to be judged by the number. I’ve also had mature animals try to convince me that they’re only 2 years old. Yes, animals do have a sense of humor and play jokes on us.
The bottom line is, some animals know their accurate age, some don’t. In most cases the information the animal provides about its age and life events gives us a pretty good idea of its true age.