DENVER -- A task force is changing the rules for dog breeders in Colorado in an effort to crack down on so-called puppy mills without changing the law.

Puppy mills are substandard mass breeding operations where animal rights activists have said disease and overcrowding run rampant.

"The animals are kept like cash crops; they're not treated as pets," said Holly Tarry, the Colorado state director of the Humane Society of the United States.

The HSUS has been fighting for tougher anti-puppy mill laws in Colorado, but a bill that would have limited the size of breeding facilities was shot down in a House committee this year, after breeders said it would put them out of business.

The debate accomplished something, though, supporters said.

Breeders later agreed to an increased licensing fee to pay for another investigator and it opened the door for the task force doing the rule review.

The task force is made up of state regulators, breeders and animal rights activists, and it is revising rules for dog breeders line by line.

"Through the rules, we can make pretty significant changes in how those facilities operate and how they care for the animals," said Dr. Kate Anderson, the administrator of the Pet Animal Care Facility Act.

Dog breeders were at the table, as well, as task force members discussed how large cages should be, how long dogs should be left in them and how often the dogs should be exercised.

"The dog breeders play a big role in that. We want what's best for the dogs," said Carmen Rebord, a licensed dog breeder.

The members also considered making the rules for cleaning, sanitation and tethering stricter.

This is the task force's third meeting on the rules, and while the HSUS said some issues can be addressed through rule changes, others will have to be done through the law.

"I think we are making some improvements and finding common ground -- there's still a lot of work to do," said Tarry.

Task force members hope to finish revising the rules by the end of the year so they would go into effect next year.