Colorado: State Department Of Agriculture

Rep. Beth McCann, D-Denver, said animals have been crippled in cages, injured and killed by people who raise them for mass marketing.

Her bill, introduced Wednesday, would prevent dog breeders from keeping more than 25 adult breeding dogs.

"This legislation will crack down on abusive puppy mills where man's best friend is treated like a cash crop instead of members of the family," said Holly Tarry, Colorado director of the Humane Society of the United States.

The Humane Society said one Colorado dog breeder was ordered out of business last year after state inspectors found 40 animals had starved to death on the property and six others were in critical condition.