I agree with the above, and I'll add....when looking through petfinder, look for dogs that are being currently fostered in someone's home. The foster "parent" will be able to give you a really good idea of how the dog behaves in real life, day to day. And you'll be able to arrange a meeting between your family Iincluding, of course, Earl
) and the prospective new doggie. Any good foster parent is going to be attatched to their foster dog, and will make an effort to ensure that their foster go someplece where it will really work out well for everyone.
The problem with a puppy is that feisty, rambunctious puppies might stress Earl out, and if he's rather submissive, might end up bulling him. How is he with other dogs and puppies in general?
Very generally speaking, an opposite-sex dog might be the better choice; less chance of dominance issues.
**Anecdote: early this year, I fostered a puppy...well, nobody could figure out what in heck mix he was. Possibly some sort of hound mix. Anyway, he was a baby when I got him, had him a month, he was feisty but wonderful with my three dogs and with my cats. I really saw no signs of impending attitude (and I am quite experienced with dogs.) Adopted him out at about 12-13 weeks old to a very nice couple who had a 7-year-old Pug. The dogs met twice, everything seemed great.
And it was great, for a while. They had the pup neutered at 5 months old, did at least one puppy obedience course, then at about seven months old he decided that his mission in life was to pester the Pug constantly. Not only that, he started to get attitude with other dogs, and bit a relative's dog bad enough to draw blood. At that point the couple called me and we all felt terrible about how it turned out, but they were no longer comfortable keeping the pup, now 45 lbs. Plus they were about to start a family and were concerned about this dog and a baby. Luckily I knew someone else who could foster him and he now has a good home.
I felt really guilty, thinking that surely I'd missed some signs that he was an overly dominant puppy. I wouldn't have let him go to these people and their well-mannered, older Pug if I'd had any clue! But all in all, a dog that's matured a bit is more of a known entity and a safer bet, even if it's an older puppy.