CHICAGO (CBS) – Animal rights groups say it’s long overdue and much needed – a bill introduced last week that would close a loophole in the Animal Welfare Act that allows unscrupulous breeders to sell sick, malnourished and mistreated puppies online, completely unregulated.

The bill, called the Puppy Uniform Protection and Safety Act or the PUPS act, is co-sponsored by Sen. Dick Durbin (D-IL) and Sen. David Vitter (R-LA). The legislation would require all breeders who sell more than 50 dogs annually – online or through pet stores – to be licensed, undergo inspections and meet standards of care for the animals they breed. The licensing and inspection requirements in the current law do not apply to online sellers.

READ MORE: Chaos In The Loop Leads To Shooting, Beatings; 21 Young People Arrested

“We need to have basic standards of care so that someone is looking at these facilities to make sure these dogs are treated humanely and not like a cash crop,” said Michael Markarian of the Humane Society of the United States. “These dogs are crammed into wire cages, they’re stacked on top of each other, often get no exercise, no veterinary care, no socialization or human companionship.”

The PUPS Act would also require that dogs get daily exercise, be housed in facilities with solid floors, require living areas to be cleaned daily and be free of pets and vermin. Click here to read the full text of the bill. (text of the bill here) Durbin and Vitter introduced a similar version of the bill in 2001 but it failed to advance. This time the legislation has broad bi-partisan support. It does not impact small breeders and hobby breeders only large commercial facilities.

“The media regularly report stories about dogs rescued from substandard facilities, where dogs are housed in stacked wire cages and seriously ill and injured dogs are routinely denied access to veterinary care,” Durbin said in a statement. “Online dog sales have contributed to the rise of these sad cases.”

READ MORE: 9 Killed, At Least 23 Wounded In Weekend Shootings In Chicago

According to experts, an estimated 4,000 puppy mills are operating in the U-S, producing more than half a million puppies a year. Groups like the Humane Society of the United States, say online puppy mill operators pretend to be humane and often set up fancy websites where consumers shop for puppies without ever seeing the breeding facilities. Puppies are usually shipped to buyers.

“These are some of the worst facilities that have hundreds of dogs or even thousands of dogs,” Markarian said. “They might have beautiful pictures on the website but that does not match the reality that these dogs are living in.”

Raids on puppy mills have discovered puppies living in feces and urine with inadequate food and water and in wire cages with wire flooring so their paws never touch the ground. Rescued puppies are usually sick and emaciated with visible sores. Some have severe infections and dental disease.

Animal advocates urge consumers never to buy a pet online. They recommend seeing the puppy in person and visiting the breeder to see the animal’s living conditions first hand.

MORE NEWS: Jussie Smollett Trial: Jury Could Get Case As Trial Resumes Monday

“Buying a dog over the internet is usually a recipe for disaster,” said Markarian. There’s also another option, he added. “We encourage people who are ready to bring a dog into their homes, to adopt a dog from their local shelter or rescue group as a first option. There are so many great dogs who need a forever home and need a second chance. You can find a great best friend by doing that.”