The average life expectancy of a guinea pig is 5 to 7 years. So if you decide to adopt, make sure you are there for the long haul! While rare, some guinea pigs have even lived over 10 years. Others have genetic predispositions or illnesses that shorten their lives.
Feed the right foods and learn all you can about proper care. See a vet promptly if you suspect your guinea pig is sick.
Vicki of JPGPR writes:
"Living with older pets is a bittersweet experience. You've gone through a lot together and have grown very comfortable with each other. Oldsters are usually mellow and better behaved than those pesky young whippersnappers - content to sit quietly and enjoy your company. They're less demanding of your attention and more appreciative of it. The sad part is watching your shorter-lived companion age before your eyes. As he becomes frail and fragile you realize your life together grows short. Each day is time to be cherished."
Be sure to read the rest of Vicki's thoughtful and thorough article on aging. She emphasizes the added importance of catching problems early and provides tips for ensuring your pet is eating adequately.