Supporters say that many of these crimes go unprosecuted or result in punishments they contend are too lenient, such as rehabilitation programs that can end with charges being expunged. According to state crime data, of the more than 3,500 animal abuse cases reported in the decade ending in 2015, 47 percent were not prosecuted, another 33 percent were dismissed and 18 percent ended in guilty verdicts.

“What I really, really wanted to do was get at those numbers of convictions,” said Representative Diana Urban, a Democratic state lawmaker who sponsored the legislation. “They’re innocent,” she said, referring to the animals. “They don’t really have a voice, and they are, quote-unquote, a little weaker than you are.”

Ms. Urban and others argue that violence against animals often has close ties to violence against humans, either coming as a precursor to escalating crimes or indicating a home environment where there might be domestic abuse.

But the measure touches on longstanding friction in the law over animals, which have been regarded as property but also as living, feeling creatures protected from abuse. There has been opposition to the law, including from groups such as the American Kennel Club, which opposed the statute because, as the club said in a statement, “individual owners could lose these ownership rights over their animals by having to give up those rights to third parties.”

“We have this disconnect between how people handle their animals and how the law is handling their animals,” said Kathy Hessler, a clinical professor at Lewis & Clark Law School who teaches animal law. “They’re the only sentient beings that fall into the property category.”

Animal law experts said that the prosecution of Michael Vick, the professional football player who pleaded guilty in 2007 to dogfighting-related charges, served as a turning point in the acceptance of advocates for animals. In that case, a federal judge appointed a so-called special master for the dogs involved, and animal rights activists have credited the master, a law professor, with helping to spare most of them from being euthanized.