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PITTSBURGH (KDKA) – Could a trendy type of dog food be to blame for a potentially deadly problem in dogs?

“It was a shock because they seemed normal. They seemed absolutely okay,” says dog owner Carol Salmon.

Her dogs, Delaney and Blue, are just like everyone else’s dogs in that they’re not just pets, they’re family.

And, like all other pet owners, Carol and her husband, Rob, always want the best for their dogs, including the best food.

For years, the Salmons thought that was NutriSource’s line of grain-free chicken and pea blend kibble.

But now, several researchers nationwide are questioning that brand, as well as dozens of others.

(Photo Credit: KDKA)

The Food and Drug Administration has also announced an investigation into the possible connection between grain-free food and a form of heart disease called dilated cardiomyopathy, or DCM.

“Cardiomyopathy is a disease of the muscle of the heart. So if you think of that chamber as being very elastic and good for pumping, all of a sudden the walls get thickened and it becomes inelastic and they can have a heart attack and die,” says veterinarian Dr. Mike Hutchinson with Animal General in Cranberry Township.

Delaney and Blue are among at least 158 cases nationwide now under investigation by the FDA, after they tested positive for taurine deficiency.

“Taurine is an essential amino acid that can lead to heart disease in deficiency,” says Dr. Hutchinson.

Veterinary nutritionist Dr. Julie Churchill from The University of Minnesota cautions there could be more.

“There are many cases where if we’re not looking, how do we know that they have low taurine?” she says.

Churchill is among a group of researchers studying the risk of grain-free diets.

She, as well as researchers at The University of California at Davis and Tufts University, have a working theory that suggests it’s not the lack of grains in the food that’s making dogs sick, rather what companies add in place of it.

Things like sweet potatoes, peas and other legumes, which they think might be stripping a dog’s ability to absorb taurine.

“We do know taurine is related to heart disease in certain animals. So, the fact that they found it in about 50 percent of those dogs that died that were on a grain-free diet. They also had a taurine deficiency. So was it because they were on a grain-free diet? Was there enough taurine in that food? That’s what they need to figure out. We don’t have those answers yet,” says Dr. Hutchinson.

In a written statement, Nutri-Source says it follows and will continue to follow recommendations by the FDA and pet nutrition experts, adding in part that, “pets are family, and we would never knowingly provide products that could harm them.”

They also started, “supplementing diets with taurine in hopes that it will aid dogs whether they are predisposed to DCM or already have it.”

Vets say sometimes, for a variety of reasons, that works.

It did for Blue, but it did not for Delaney. Her heart was already too damaged.

“It’s hard to wrap your mind around the fact that you have a dog that’s that sick when she doesn’t look that sick,” says Carol.

“They’re not showing any signs, they’re going along, until they reach a certain point of no return. That’s what I’m worried about,” Dr. Churchill says.

Right now, pet owners are left relying on the FDA’s guidance, or their local vet.

Dr. Hutchinson says some vets he’s talked to think the FDA is being overly cautious, but he’s actually glad they raised a red flag if, for nothing else, to make people aware.

“There was enough evidence to say let’s put out a warning: grain-free diets may not be the best thing for your pet,” says Dr. Hutchinson.

As for Delaney and Blue, the Salmon’s changed their food right after they were diagnosed, but it may not be enough.

“And that’s my fear, you know? Even though we’re treating Delaney, it hasn’t increased that much with medication and taurine. So I’m not sure how long we’ll have her,” says Carol.

So, when can we expect more clarity on grain-free pet food?

The UC Davis and Tufts studies are done, but they’re waiting for a final review.

The FDA says it doesn’t yet have a timeline for when it will publish its report.

The bottom line is check with your vet if you’re concerned about your pets.