Looking for Pet Insurance? Some Dog Breeds Will Cost More to Cover.

The most popular dog in the country for the last two years has been the French bulldog, beloved for its batlike ears and deep wrinkles. But because of their flat faces, they are prone to respiratory and eye problems.

That may be why “Frenchies” are the second-most-expensive dog breed to insure, behind the Cane Corso, a mastiff, according to Spot Pet Insurance, one of dozens of companies selling pet health insurance. The company recently ranked the costliest breeds of dogs and cats to cover, noting that some purebreds may be more expensive because their genetic makeup makes them susceptible to certain health conditions.

The rankings were based on average policy premiums as well as the most costly claim paid for the breed, said Trey Ferro, chief executive of Spot Pet Insurance, which has 330,000 active policies. (The dog’s age and the type of policy chosen can also affect costs, the company said.)

At the other end, the cheapest breeds to insure were the Chihuahua and the Maltipoo, a Maltese-poodle cross.

Dr. Jerry Klein, chief veterinary officer for the American Kennel Club, noted that a majority of dog breeds on the insurer’s most-costly-to-cover list — the compact Frenchie aside — were larger animals, while small breeds dominated the least-costly list.

“Big dogs cost more, period,” Dr. Klein said. They eat more, they need bigger crates and other equipment, and if they need medical care, they require larger doses of medicine and anesthesia, he said.