Two years ago we were in the same situation. We lost my husband's old dog so since I wasn't really that attached to her, I encouraged hubby for us to visit a humane society nearby to just "look and see", we-do-not-need-to-get-one-dog. He reluctantly went with me. We ended up getting a young-ist 7-week-old rottweiler. He was beautiful and intelligent and very advanced for his age. Nearly nine months later, we have to let him go -- he had canine renal failure. We had the best oncologist with a practice near us, a place where you can't enter his door if you do not have at least $500 to spend for our animal. $4000+ later, we were told that should our baby survived, he won't have a quality life, we had to let him go. We were advised that the next time we get another dog, we should ask for a blood test to see if our chosen one is healthy throughout.
Husband was inconsolable for weeks so I decided to look for another rottie. I found one in Dallas (Texas) at a Rottweiller Rescue. After a few almost endless arrangements, we finally flew to Dallas to pick him up. While at the airport, we called up our vet and asked for a complete checkup (including blood tests). In short, now the love of our love who used to be a mangy, wormy, fleabag is now a healthy 1 and half year, 125.5 lbs spoiled rotten baby who ended up being hubby's sidekick.
I am sorry for your loss. My advice is ... concentrate on the other two you have right now. They are there for a reason.
Izzie