Last week, Mars, the company best known for brands like Snickers, Skittles, and Wrigley’s gum, purchased AniCura, a network of 200 animal hospitals spanning seven European countries.

On its face, Mars’ acquisition of AniCura might not seem to make business sense. What synergies could possibly exist between making candy bars and taking care of sick dogs and cats? Yet, it turns out the deal is part of a much larger trend in which Big Food companies are cornering the business of both feeding and caring for pets.

Americans are shelling out more for their furry friends, and processed food companies want in on this growing pet care market to make up for stagnating sales of processed people foods. Last year, Americans spent $29 billion on pet foods, double what pet owners spent in 2000, and in the past five years alone, American spending per pet increased 25 percent. Since 2015, companies like Smuckers and General Mills have acquired popular pet brands including Milk-Bone, Meow Mix, and Blue Buffalo. Altogether, just five companies, Nestle, Mars, Smuckers, Colgate, and General Mills, represent 70 percent of retail pet food sales.

Unlike other food companies, Mars has been in the pet business for over 75 years, and more of their revenue comes from pet products than candy. They are the largest global pet food company, with popular brands of dry and wet foods, like Pedigree, Iams, Whiskas, and Cesar, as well as snacks and therapeutic blends, such as Greenies dental chews and veterinary-prescribed Royal Canin.

Over the past decade, Mars has looked to capture more of the pet-spending boom by expanding into pet health care. Today they are America’s largest single veterinary provider. Since 2007, the privately-held corporation has bought animal hospital and laboratory networks including Banfield, Blue Pearl, Pet Partners, VCA, and now, AniCura. In total, Mars employs over 9 percent of all U.S. veterinarians who serve pets.

Mars’ move also raises questions about potential conflicts of interest and uncompetitive advantages when it comes to Mars-employed vets recommending their products, including pet foods, dental chews, and DNA tests.

“Mars’ buying up this veterinary hospital chain, it’s essentially the good, the bad, and the ugly,” argued veterinarian Dr. Michael Fox, author of the syndicated column, Animal Doctor. The good is that corporatized veterinary medicine can provide some standardized best practices, but the bad is that it runs the risk of constraining vets with too many required protocols.

“I am concerned that they will set up protocols that are financially driven, and not in the best interest of animals themselves or the clients,” says Dr. Fox, “I would include in that list the probability that they’re pushing special prescription diets, especially Mars products.”

Prescription diets, or therapeutic blends, can treat anything from pet obesity and diabetes to kidney stones and skin disease. But these foods can only be purchased with a veterinarian’s recommendation and they come at a high premium. Mars’ acquisition of animal hospitals makes them both a maker and a gatekeeper for these particular products.

Banfield and VCA executives have said they do not require or encourage doctors to stock or recommend Mars brands, but by owning the hospitals Mars has a strong incentive to engage in just that kind of promotion. Even if Mars-employed vets make independent and informed decisions to recommend Mars products, the mere existence of this incentive creates room for clients to mistrust veterinarians’ motives.

There is also evidence that VCA, in particular, has pressured vets to increase service and product sales before. An investigation by Bloomberg found that VCA sent some veterinarians records of the number of products they sold, like heartworm tests, with suggested monthly sales targets. VCA has also clearly stated their motives to increase profits by pushing more services. In an annual financial statement, the company that said their business strategy was “to leverage our existing customer base by increasing the number and intensity of the services received during each visit.”

Ultimately, healthcare systems should make it easy for veterinarians, and all medical professionals, to make the choices and recommendations that are best for their patients. But as pet food companies play a larger role in pet health care, it creates conflicts of interest that could potentially influence practices and jeopardize trust.