TOPEKA, Kan. (CBS) – A recall of Hill’s Pet Nutrition canned dog food for potentially toxic levels of Vitamin D is expanding.

Hill’s first recall in January involved about 13.5 million cans sold nationwide and led to an unknown number of dog illnesses and death, CBS News reports.

“We believe that hundreds, if not thousands, of pets have died or become seriously ill as a result of eating Hill’s foods with toxic levels of vitamin D,” emailed Nyran Rose Rasche, a Chicago-based attorney with Cafferty Clobes Meriwether & Sprengel, which filed a class action against Hill last month.

Canned food items like lamb, beef and chicken and vegetable stews have been added to the recall after the company discovered that they may also have elevated vitamin D levels. The new lot numbers can be found on the FDA’s website.

Where to find the lot number on the Hill’s dog food recall (Image credit: FDA)

It’s important that dogs get some vitamin D, but too much can lead to vomiting, weight loss and, in rare cases, potentially life-threatening issues like renal dysfunction.

Hill’s says it has received a “limited number” of complaints of pet illnesses related to the recall.

“As a company, and as pet parents ourselves, we deeply regret the concern that this recall and subsequent expansion have caused pet parents and any possible effect the recalled foods may have had on pets,” Hill’s said in a statement.

Hill’s says dry dog food, cat food and treats are not affected by the recall.

Read the full FDA recall notice here.