8 could be middle age , with long life ahead in some lines and in others it could be pretty geriatric and nearing the end.
You have to know the background for longevity within the line , within the family .
I see from your other thread that you have not seen the dog yet , so the question is how old is she in the picture .
You want her for a service dog - is she trained and certified for this ?
You have to question the circumstances around her being offered at this age . Was she someones service dog and she was retired because of some issue , or did her person decline in healthy or even decease? If your husband needs physical assistance you don't want to take on a dog that soon will require assistance herself .