The source comes from PETA which is not really reliable.

If you buy dog or cat food from the Iams Pet Food Company, you need to
visit a website iamscruelty.com.
Apparently, Iams keeps cats and dogs to TEST their foods on before it
goes to market. I had no idea pet food manufacturers used animals to
make a better food - but some do! Iams keeps cats and dogs in cages to
take blood, stool, urine and even muscle tissue samples as they
conduct nutritional testing. I was extremely upet to learn this and
immediately researched pet food companies that do not test on animals
- and there are a lot of them! My puppies now eat Wellness food and
they love it! No animal testing on this stuff!

Anyone who loves cats and dogs MUST visit iamscruelty.com and send an
email to Iams and tell them to stop testing on poor kitties and
puppies!!!