Attention all pet owners. 

The U.S. Food and Drug Administration is issuing a warning letter to Midwestern Pet Foods. 

The FDA says an investigation began with reports of dogs becoming ill after eating 'Sportmix Brand dry dog food' made by Midwestern. 

Samples were found to contain extremely high levels of aflatoxin, a type of mold, as high as 558 parts per billion. Compare that to the fact the FDA considers anything more than 20 to be dangerous. 

The company issued a recall in January which expanded in March after the dog food was found to be contaminated with salmonella as well. 

So far, the FDA is aware of 130 deaths and more than 220 illnesses linked to the pet food.

The FDA requests a written plan of action from Midwestern.