After concerns were raised about a current U.S. investigation into whether pet food widely available in Canada could cause a deadly canine disease, pet owners should be aware of changes in their dogs’ behaviour, a veterinarian says.

Canine dilated cardiomyopathy (DCM) is not an uncommon condition, according to veterinarian Sarah Dodd. But while some causes of the disease are genetic, dogs may be more at risk if they eat certain dog food.

The Food and Drug Administration has received more than 500 complaints that allege the development of DCM is linked to pets consuming certain brands of dog food.

DCM is “a condition where the cardiac muscle weakens and the heart enlarges and is unable to effectively pump blood around the body anymore,” Dodd said. The impact on the body varies between breeds, but the disease can be fatal.

The FDA first raised concerns about certain brands of dry dog food being linked to DCM last summer, but their most recent report was the first to name specific brands.

A brand called Acana, manufactured by Edmonton-based Champion Pet Foods, showed up the most often in complaints, at 67 times. Orijen, also a Champion brand, was referenced in 12 complaints. Two other brands manufactured in the U.S. but available for sale in Canada were mentioned in more than 50 complaints: Taste of the Wild and Zignature.

Many of the products named in the complaints shared the common theme of being marketed as grain-free.

Concerned pet owners who want to be on the lookout for symptoms in their own dogs should be wary of any shift in personality, Dodd said.

Along with coughing and an increased respiratory rate, a main symptom of DCM is something called “exercise intolerance,” Dodd said. “So your dog doesn’t want to go for as long a walk, or are struggling to play as much, might be a little quieter than usual.”

She acknowledged that these symptoms were not very specific, but added that “any time that you see anything that’s outside of the normal, you know, your dog just isn’t quite themselves, that’s a good reason to have a visit to the veterinarian, regardless of whether they’ve had a grain-free diet or not.”

Older dogs and larger breeds such as Great Danes, Irish wolfhounds and Doberman pinschers are more at risk for genetic reasons.

Champion Pet Foods said in a statement that they are taking the DCM investigation seriously, but that their own research “and the millions of pets who have thrived by eating our food over 25 years, have shown that Champion pet foods are safe.”

Zignature and Taste of the Wild have released similar statements, citing favorable research while confirming their commitment to food safety.

Canada doesn’t have its own investigation running because pet food is not regulated in Canada, according to a spokesperson for the Canadian Food Inspection Agency.

“In Canada … the regulation of pet food is based on the consumer packaging and labelling act, and the competition act, and that’s more to do with how pet foods are marketed to consumers,” Dodd said. “What’s on the bag more so than what’s in the bag.”

But consumers in Canada can use what’s on the bag to help them find better pet food, she said.

The thing to look for, she said, wasn’t the ingredients used, but the nutrients.

Dodd suggested “looking for a diet that has a nutritional adequacy statement on the label.” This would say “something along the lines of the diet being formulated according to the nutrient profiles published by … the Association of American Feed Control Officials.” Or pet owners could look for a label certifying that the dog food had “undergone feeding trials in accordance with AAFCO guidelines.”

No recalls have been issued for any of the brands identified in the FDA’s ongoing investigation, because a definitive connection between them and DCM has not yet been proven. The FDA has not advised consumers to avoid any certain brands at this time, but stressed that pet owners keep a close eye on their animals’ behavior.