What you may not know is that many breeds today have very small populations. If some breeds were any other kind of animal they would be considered endangered. You may find it hard to believe, but breeds can become extinct. If you read any histories about dog breeds, you will find lots of references to breeds that are gone now. Countless breeds have become extinct over the centuries. In some cases we have some of their descendants because they contributed to newer breeds, but not always. Some people might not care if particular breeds become extinct, but if you are a fan of a breed, then this might matter to you. From a genetic viewpoint, it’s always good to have a wide selection of dogs that contributed to a breed’s foundation. You never know when it might be necessary to reintroduce some of the genes from an older breed for health reasons. If those breeds are extinct, that’s no longer a possibility.
Keep in mind that large dogs are more expensive to keep. They eat more food, which costs you more money. Tick and flea preventives cost more for large dogs, as do other mediations.
If you own one of the 11 "riskiest" dog breeds -- which include Rottweilers, Pit Bulls and Doberman Pinschers -- you may face some big homeowners or renters insurance headaches, even if the only things your pup has ever taken a bite of are his Alpo and bone. These days, companies offering homeowners and renters insurance are pickier than ever about which types of dogs they’ll insure and which they won’t
If you do not have time to exercise your dog daily with a brisk walk and lots of running choose a breed that does not have high exercise requirements. All of the breeds who require high amounts of exercise make terrific jogging, hiking, and ridding companions. So if you want your dog to accompany you on long runs choose one of these highly active breeds built for endurance and as much exercise as you can throw at them - they will love you for it (and a tired dog is not destructive).