The illegally purchased dogs came from shelters, the street, even "free to a good home" pet ads. What the hell?!

You might have never given much thought to how medical researchers get dogs for their labs. The truth might be worse than you imagined.

On Thursday, according to a story by Philly.com, Floyd and Susan Martin pleaded guilty in federal court to illegally purchasing dogs to sell to research facilities. How many dogs? Hundreds of them. To what institutions? Big ones, like Johns Hopkins and Columbia University.

And they received hundreds of thousands of dollars for those dogs, between 2005 and 2010.

The case throws light on the sordid world of dog-dealing for biomedical research.

According to the Philly.com, the Martins, who are “random source” dog dealers, “bought their animals by the hundreds from shady individuals known as ‘bunchers,’ who collect dogs from auctions, shelters, the street, theft, and ‘free to good home’ pet ads.”

Authorities say that two bunchers bought hundreds of dogs from different sources in 10 states, then sold them to the Martins for $50 to $75 each. The Martins then sold the dogs to labs for hundreds of dollars in profit per dog.

“We’re talking about an abuse-ridden system of acquiring animals for research,” said Nancy Blaney, senior federal policy adviser for the Animal Welfare Institute, a national advocacy group. “‘Random source’ is what it sounds like it is. They can get animals from individuals who respond to ‘free to good home’ ads or animals being stolen. We know because they have been traced through microchipping.”

This is not what people had in mind with the Animal Welfare Act of 1966, which attempted to establish humane standards for animals in labs and regulate dealers who sold to them.

The Martins are Class B or “random source” dog dealers, a designation that is federally sanctioned but controversial. These dealers may purchase dogs from unlicensed bunchers, but no more than 24 dogs per buncher per year. The Martins ran into trouble by buying hundreds of dogs from just two bunchers.

The silver lining in all this is that only 3 percent of dogs used in biomedical research in the U.S. come from random-source dealers, and that number is decreasing because of the controversy of using former pets as lab subjects.

Most labs buy from facilities whose dogs are bred for research.

As for the Martins, they made a deal with prosecutors, with Floyd pleading guilty to one count of mail fraud, for which he will serve a year in prison, and Susan pleaded guilty to a count of conspiracy, for which she will be placed on probation.

Via Philly.com