I get mine from other breeders, rat rescues (two pets, males that I did breed), and pet stores that I trust. I brought home a rat one time that had the 24 hour flu and 10 of my 13 rats died within 2 days. It was terrible! That's one thing you have to know when you are breeding and be really careful about what you are bringing home. I would definitely quarantine for a couple days just in case that particular rat has the flu. Some can carry it and not show signs, but at least you tried to keep your colony safe.