If I were you, I'd get a mongrel. They tend to be healthier and live longer. The dog that I grew up with was a mixture of poodle, Irish setter and schnauzer, and she lived to be 19 years old.
I wouldn't recommend a large dog. You'll end up paying a fortune in dog food, and large dogs can be hard to control when they're younger and full of energy. But I wouldn't get a small dog either. They tend to have fear issues around other dogs and often overcompensate with agression or permanent barking. Small dogs are also more prone to health issues, behavioral problems and hyperactivity. I suggest looking for medium-sized mutt
If you adopt a dog from an animal shelter, be prepared for high vet bills. Animals at shelters are often very stressed, might be malnourished due to food competition, and usually get only cheap food or a very irregular diet due to different brands in food donations, which weakens their immune systems. They also live on a small space with lots of other animals, which is a perfect breeding ground for diseases. And you never know how often a pet has been adopted before. It might be a problem animal that several people have adopted and brought back.
One of my cats is a rescue, and although I love her to bits, the first months were a total nightmare. She had a tapeworm and roundworms -- they assured me that she was wormed, but that was either a lie or she had caught worms again from another cat -- a bad cough and short breath (probably from worms in her lungs), a giardia infection, and constant diarrhea. On top of that, she refused to take her meds and infected my other cat with her giardiasis and diarrhea Giardia are extremely difficult to get rid of. I spent all day disinfecting litterboxes and toys, washing blankets, cleaning carpets, and trying to somehow get the cats to take their antibiotics.
I don't know if I would ever adopt a rescue again after this experience. You also never get a rescue to trust you on the same level as a pet that you've raised yourself, which makes it harder to give them medication or take them to vet (although that should be much easier with a dog). On the plus side, difficult environments like shelters often make for highly intelligent pets. My rescue is scarily smart
Last edited by CrazyCatLord on 10 Mar 2012, 10:12 pm, edited 1 time in total.