LAS VEGAS - You can buy just about anything online now — but when that purchase is a brand new puppy, how much do you really know about where or how the puppy came to be? Thousands of puppies are bred and sold by large-scale commercial breeders often called "puppy mills."

These dogs can come with diseases that can ring up huge vet bills for the unwitting buyer, says Melanie Kahn, senior director of The Humane Society of the United States' Puppy Mills Campaign. She explains lots of these pups are bred and kept in filthy, cramped cages where humane treatment takes a backseat to profits.

"When we've gone on raids and rescues, we see dogs that are just filthy. They have severe illnesses and diseases, often times they're genetic diseases. We've seen facilities where the dogs haven't been fed."

This year, Nevada has enacted new laws regulating commercial dog breeders, but there are currently no federal regulations covering breeders who sell directly to the public.

Stacia Newman, vice president of Nevada Political Action for Animals says the new state law (SB 299) provides commonsense standards for puppies in the care of commercial breeders in the state.

"Veterinarian treatment if the animal is sick or injured, fresh water daily, fresh food daily; the cages so they could actually turn around."

The Humane Society recommends adopting a dog from a local shelter or a rescue first, even if you are looking for a specific breed. Kahn points out that about 25-percent of homeless dogs are purebred dogs. If you decide to go through a breeder, do a little research first, she cautions.

"We encourage people to go to a responsible breeder. That's someone who does not breed their dogs purely for profit, someone who genuinely cares about the welfare of the dog."

Kahn's organization is gathering signatures on an online petition asking the Obama administration to require that commercial breeders be covered by the USDA's Animal Welfare Act regulations, which would mandate minimum standards for humane treatment.