When I left home I adopted 2 kittens, then eventually got the ex to agree to a puppy - puppy was fine with the cats as they put her in her place, I had that puppy over 12 years.
With the current DH when we had the 5 dogs, we managed to adopt 4 of them the same age, adopted over the years so we didnt even consider their ages - until we lost 4 of them in 18 months all aged 12
We still have the last of the 5, he is 12.5 now and was the puppy of the group. We also lost a rescue Labrador age 4 a couple of years back to bone cancer. It has taken me this long to realise how hard each loss hit me, hopefully I will learn to grieve better in future and not bottle things up.