Counter for age as field in CMS

Hi,
I created a website for an animal shelter. Each dog and cat has its age listed. Is it possible to add a field in the CMS that would automatically calculate the animal’s age?
For example, when adding a dog, I would enter its birth date, and this field would automatically calculate its current age. Some animals are young, so I enter their age in months, so ideally, the field would display both years and months. Is something like this possible?

Information can be divided into static data and calculated data

The calculated data should not be stored within the CMS, as it changes dependent on the time it’s viewed

So do store the animals’ birthdate, and only calculate the age when displaying it on the site.