It depends on what type of animal it is. From the old aging Tortoises to the Quick Dying House Flies.

Genetics likely plays the most significant role in determining an individual's life span and the aging process. Factors such as inherited traits, family history of diseases, and genetic variations can greatly influence how long someone lives and how they age.

Click on the button you usually would to save and quit, but instead click options. a screen will pop up. then, click the gear at the top of the screen. you will get a new window that allows you to turn aging off, up your life span to 390 day, ect.

progeria

a rare congenital abnormality characterized by premature and rapid aging, the affected individual appearing in childhood as an aged person and having a shortened life span.

yw :)

Yes, you can. Go to settings where you can determine the life span of your Sim. Then choose Disable aging or something to make your Sim live forever. Hope this works!