DETROIT (AP) — Kibbles for Fido? Nope. These days, he’s getting diced chicken with sweet potatoes and spinach.

U.S. pet owners are increasingly feeding fresh food to their dogs and cats. Some order pre-proportioned meals of meat and vegetables or frozen raw meat online. Others find them in refrigerators at big retailers like Walmart.

Later this spring, Petco and its partner, California-based JustFoodForDogs, will open a kitchen at its flagship store in New York, where it expects to make 2,000 pounds of fresh pet food every day.

Proponents say fresh foods preserve nutrients better than canned or dried ones, mimic ancestral diets and improve pets’ health.

“Just as people have become skeptical of highly processed foods for themselves, they’re looking critically at their pets’ foods as well,” said Amy Zalneraitis, part owner and chief brand officer of We Feed Raw, a 10-year-old raw food meal plan service based in Maine. “They think: How could something with a shelf life of over a year be better than real, fresh food?”

But some veterinarians question the trend.

They say established pet food companies like 51-year-old Royal Canin are backed by decades of research, while the verdict is still out on fresh food.

The Food and Drug Administration says raw pet food has a high risk of bacterial contamination. The agency is also investigating a link between grain-free diets that contain peas, lentils and potatoes and elevated levels of heart disease in dogs.

“There are so many essential nutrients, from all different classes, that need to be considered,” said Dr. Lindsey Bullen, a pet nutrition specialist at the Veterinary Specialist Hospital of the Carolinas. “If they are too high or too low, or in an inappropriate proportion, it can cause significant problems for that pet that the client might not see for months or years to come.”

Bullen says about 20% of her clients feed their pets fresh food. She said she questions them about the recipes they’re following to make sure that they’re providing essential nutrients. Canine and feline supplements can help round out fresh meals.

Pet food trends tail human ones. When gravy was popular in the 1950s, Gravy Train dog food appeared. In the 1980s, Fancy Feast cat food mirrored a growing interest in gourmet food.

This time, younger buyers are fueling the trend, choosing pet foods they consider safer and more natural, consulting firm Mintel said.

U.S. sales of fresh pet food in grocery and pet stores jumped 70% to more than $546 million between 2015 and 2018, according to Nielsen. That doesn’t include online sales or people making their own fresh pet food. It’s still a fraction of the $25 billion U.S. pet food market.

Turkey necks and gizzards for Gracie and Takaani, two German shepherds who live in Oconomowoc, Wisconsin, with their owners, Deb and Joe Colgan.

Deb Colgan was initially hesitant when she caught her husband feeding raw meat to their two German shepherds seven years ago. But after researching the benefits, they started buying raw meat and bones from the grocery store. She works with her vet and adds supplements like vitamin E, salmon oil, probiotics and a joint supplement.

One of her dogs stopped vomiting regularly and gained weight. The other stopped getting ear and urinary tract infections. Those dogs eventually died, but the Colgans have continued the diet with two new dogs.

“It’s very much a relief they are so healthy, and we do believe it’s because how they eat,” said Colgan, of Oconomowoc, Wisconsin. “I can’t imagine us ever going back to commercial.”

Feeding pets raw food is the most expensive option. According to Nielsen data, the average fresh pet food costs $5.26 per pound, while the average frozen raw pet food is $6.23 per pound.

Colgan spends $300 a month on fresh pet food, including three 10-pound rolls of meat per week, vegetables, fruit, fish and freeze-dried dog treats. By comparison, 30 pounds of Freshpet Vital brand turkey, peas, carrots and rice, which is sold in refrigerated tubes, costs about $85. A 31-pound bag of Purina One Smart Blend dry dog food costs $33.79 on Amazon.com.

NomNomNow, which makes pre-proportioned fresh meals specific to each pet, says its service costs $2.60 to $3.80 per meal for a 35-pound dog and $1.50 to $2.80 per meal for a 12-pound cat. That’s a lot more than a 55-cent can of Friskies, but it’s in line with some prescription pet foods.

The San Francisco-based company, which was founded four years ago, says it’s making hundreds of thousands of meals per month and delivering them to customers in 48 states.

“The general health consciousness of Americans is transferring to their pets because we do consider pets as part of our family,” said Lynn Hubbard, general manager of NomNomNow’s Nashville, Tennessee, production facility.