When it comes to dogs, size does make a difference. Most big dogs don't belong in an apartment, or with people who can't manage them physically. Of course, energy and temperament also enter into the picture, but think carefully about the adult size before you get the puppy. One of the saddest things I remember seeing was a sign on the shelter cage of a sweet, normal-size (meaning enormous!) one-year-old St. Bernard. The sign stated the reason his owners gave him up: “He growed too big.”
Size can have practical implications. If you travel with your dog, keep in mind that a bigger dog will need more room in the car. If you take his crate along, it will be bigger and heavier to move in and out of the car, motel rooms, or your relatives' homes (if they let you in!). For many people, the extra effort to own a large or even giant breed is worth it, but be honest with yourself and fair to the dog before you make the commitment.
A dog's size also affects the cost of maintaining him properly. A big dog's food bill will be higher. If you need to board him, that will cost more. He'll need a bigger crate, bigger bed, bigger toys—all more expensive than smaller ones. He'll also need larger doses of heartworm and flea preventative and other medications. Be sure you can afford a big dog before you get one.
Tiny, fragile dogs don't belong in homes with rambunctious kids. Your current pets may also be a factor in deciding whether to get a small dog. If you have a big, rowdy dog or two, or a dog with high prey drive, be sure that you and everyone in your family are committed to keeping a small dog safe before you bring one home.
More Hair or Less?
There's nothing prettier than a well-coifed dog with a beautiful coat, and nothing cuter than a terrier with his rough coat and spiffy whiskers. But dogs with impressive coats don't look that way by accident. Poodles, terriers, and some others may need professional grooming to keep their coats in good shape.
Dogs with longer coats usually need more grooming, especially if they spend time where they can pick up burrs and other bits of plant matter in their coats. Matting can be a problem, especially with silky coats that tangle easily. Some dogs need specialized grooming. If you choose a dog with a high-maintenance coat, be sure you understand and are committed to proper coat care. Many breeds, both long-haired and short-haired, shed. If you don't like to groom and vacuum, and can't stand dog hair on your clothes and your furniture, you'll probably do better with a dog that sheds less.
Shedding and brushing aren't the only considerations when it comes to coats. Some breeds have oily coats designed to protect the dog when he's working in wet conditions. Oily outer coats can develop a distinctly doggy aroma, especially if the dog gets wet. If you choose a breed with an oily coat, you'll probably want to bathe the dog more often (unless you're showing the dog, in which case you need to preserve the correct texture).
Jogger or Couch Potato?
Your activity level dictates to a certain degree what type of dog will best suit you. If you're an armchair athlete who wants a canine lap-warmer, you need a smallish dog that's content with minimal exercise. If you jog and want a canine partner, you need to choose a dog with enough energy and size to keep up. If the dog has to sit home while you go off to meetings, sports events, lessons, and jobs, you certainly don't need a high-energy, active breed. In fact, maybe you don't need a dog at all.
High-energy dogs require lots of exercise and training. For some breeds that means more than an hour every single day of hard exercise—running, playing fetch games, long walks, and so forth. Such dogs also require obedience training so that you can control the energy when you need to do so. Many of the dogs from the herding, sporting, and working groups fall into this category. The need for exercise applies particularly to young dogs, but some individuals retain their high energy well into adulthood. I live with a 10-year-old Australian Shepherd named Rowdy, who still lives up to his name! A high-energy dog who doesn't get the exercise he needs is not a pleasant companion or housemate, and is likely to develop behavioral problems out of boredom and frustration.
Chew on This
Herding, Sporting, Hound, and Working breeds have energy and stamina to spend long days in the work for which they were developed. Most dogs from these groups need owners who are committed to giving their dogs an hour or two of exercise every single day.
If you have the time to spend with your dog, there are plenty of activities for the two of you to pursue. Hiking, jogging, backpacking, and playing long games of “fetch the tennis ball” are fun. If you and your dog enjoy training, you might consider obedience or agility competition or tracking. You might also be interested in activities that test your dog's instinct for whatever his breed was developed to do. Training for and participating in herding, lure coursing, earthdog events, sporting tests and trials, and other sports will create a wonderful bond between you and your dog, and help channel all that energy into having fun.