SAN JUAN, Puerto Rico (AP) — A man who bred dogs for fighting for decades, selling them worldwide and exhibiting “extraordinary cruelty,” was sentenced to seven years in prison, the U.S. Attorney’s Office announced Friday.

Antonio Casillas Montero owned Stone City Kennels in Puerto Rico and had been accused of conspiring to violate the Animal Welfare Act. He pleaded guilty in May and was sentenced in late September.

Authorities said he ran his business for more than 35 years, with dogs participating in more than 150 fights in countries including the United States, Mexico, Ecuador and Peru.

“The government has not found a comparable case of someone with as many dogfights for as many years as Mr. Casillas,” prosecutors said during sentencing.

Authorities accused Casillas of letting dogs die from their injuries instead of removing them from fights, which sometimes lasted more than an hour. In addition, dogs seized from his property had pustules, fungus, were limping and had jaw clamping, according to court documents.

“Casillas exhibited extraordinary cruelty,” prosecutors said during sentencing.

They noted dogfighting is an open secret in Puerto Rico that is not targeted by local law enforcement.

In addition, prosecutors noted that “a willingness on the part of certain veterinarians in Puerto Rico to aid Casillas facilitated his years of dogfighting.”

He would inject dogs with steroids and contact certain veterinarians to obtain health certificates required to transport some dogs to the Dominican Republic via ferry, officials said.

Casillas also was accused of breeding and selling fighting dogs for thousands of dollars and shipping them to people across the globe.