Dog-bite claims for U.S. insurers climbed 5.5 percent last year to 17,359, breaking the record from 2003. New York had the costliest attacks among states with the most incidents.

The assaults cost the insurance industry $483.7 million, the Insurance Information Institute said Wednesday in a statement. The average cost in New York State was $43,122 per claim, compared with $27,862 nationwide.

Insurers and health officials are seeking to limit the confrontations, which accounted for more than one-third of homeowners liability claims costs last year, the I.I.I. said. Almost 4.5 million Americans are bitten by dogs each year, and about a fifth of those incidents require medical attention, according to the U.S. Centers for Disease Control and Prevention.

“Dog attacks are directly attributable to the owners of the dog—that’s almost always true,” said Kenneth Phillips, a Los Angeles attorney who represents victims of dog bites. “Most of the time when this happens people are not leashing their dogs.”

Dog owners are encouraged to play nonaggressive games with their pets, such as “go fetch,” rather than tug of war, the I.I.I. said. Parents should tell children to avoid disturbing animals while they are eating or sleeping, and dogs shouldn’t be left alone with infants, according to the statement. National Dog Bite Prevention Week begins May 18.

California, the most populous U.S. state, had the highest number of claims from dog bites last year at 1,919. The attacks cost an average of $33,709 in the state.

State Farm Mutual Automobile Insurance Co., the biggest provider of residential coverage in the U.S., said an increase in costs has coincided with a period in which there were fewer dogs in the country. Phillips said the popularity of more aggressive animals, such as some pit bulls, may have fueled higher expenses.

“You don’t have man’s best friend here,” the lawyer said. “When it goes off and hurts a person, it lays a lot of pain on them.”

Victoria Stilwell, the dog trainer who is the star of Animal Planet’s “It’s Me or the Dog” and is working with Bloomington, Ill.-based State Farm to improve safety, said the answer isn’t to ban certain types of pets.

The solution is to “raise awareness of canine behavior through education, as well as encouraging responsible dog ownership,” she said.

The U.S. Postal Service reported that 5,581 employees were attacked by dogs in 2013. Houston had the most attacks on postal employees with 63, while Los Angeles was second with 61, USPS said in a separate statement Wednesday.

“There’s a myth we often hear,” Linda DeCarlo, the postal service’s manager of safety, said in the statement. “Don’t worry, my dog won’t bite.”