Pennsylvania Republican Senate nominee Mehmet Oz speaks during a GOP leadership forum at Newtown Athletic Club on May 11, 2022.
CNN  — 

Mehmet Oz’s medical research record is coming under new scrutiny in the already contentious Pennsylvania Senate contest, prompting the Republican nominee’s campaign to vehemently deny allegations by Democrat John Fetterman that he abused animals.

The controversy stems from Oz’s time as the “principal investigator” in the Columbia University Institute of Comparative Medicine labs, where Oz’s research involved the use of dogs, pigs, calves, rabbits, and rodents, according to public reports and documents reviewed by CNN. Columbia’s website notes that a principal investigator “has overall responsibility for safety and compliance in his or her laboratory,” although noted that many of the lab’s responsibilities can be delegated to a “competent designee(s).”

The website Jezebel published a report this week claiming that between 1989 and 2010, more than 300 dogs were killed in the process of this research, according to the site’s review of Oz’s published studies. Additionally, Columbia University paid a $2,000 fine to the USDA for violations of the Animal Welfare Act in 2004 after the university investigated its animal research practices, including research conducted by Oz.

In its 2020 guidelines on animal euthanasia, the American Veterinary Medical Association acknowledges the killing of healthy animals, including in conjunction with biomedical research, is “unpleasant and morally challenging,” but also “a practical necessity.”

“The AVMA recognizes such actions as acceptable if those carrying out euthanasia adhere to strict policies, guidelines, and applicable regulations,” it says.

Animal rights groups have long opposed such killings.

In 2004, People for the Ethical Treatment of Animals alleged that Oz was “responsible for the extreme suffering endured by dogs used in his heart experiments,” citing whistleblower testimony and documents from an internal investigation by Columbia University.

Now, Oz finds himself under attack from Fetterman, the lieutenant governor of Pennsylvania, for his research practices, causing his campaign to push back.

“Doctor Oz never abused any animals, and suggesting otherwise is ridiculous,” said Brittany Yanick, a spokeswoman for the Oz campaign, calling the allegation “totally false and preposterous” and blaming the Fetterman campaign for pushing the story to “every reporter under the sun to distract voters from the issues that really matter.”

Yanick added: “Dr. Oz was not in the operating room when the operations were done, he wasn’t present during the post-op treatments, no one alerted him of the problem until after the cases were finished and he does not condone the mistreatment of animals,” Yanick said.

The allegations, however, have injected a new line of attack into one the most closely watched Senate races in the country, a matchup between Oz and Fetterman that represents Democrat’s best chance to pick up a seat in the evenly divided body. A CNN Poll of Polls average shows a close contest in the commonwealth with Fetterman having the support of 50% of likely voters compared to 45% who back Oz.

The lieutenant governor has responded to the report on Twitter, writing on Wednesday, “Dr. Oz kills puppies. That’s the tweet” and sarcastically responding to an Oz tweet from May where the Republican posed with a dog by asking, “Has anyone seen this dog since May?”

“Dr. Oz is a puppy killer,” Fetterman wrote shortly after the Jezebel story published.