An expert pain management doctor testified yesterday that untreated chronic pain will break down the human body.

Dr. Forest Tennant was summoned from West Covina, Calif., to testify in defense of Dr. William Mangino, a pain medicine doctor being prosecuted for alleged Medicaid fraud and violations of the state’s drug act.

Tennant, who runs a pain research clinic, was the only defense witness in the case, which is expected to go to the jury today after closing arguments.

Attorney Thomas W. Leslie questioned Tennant, who said Mangino’s practice followed pain medicine standards when he worked as a consultant in a Union Township clinic with two other doctors.

His testimony contradicted that of prosecution witness Dr. David Evanko, who spent most of last week on the witness stand. Evanko, a Butler physician, testified about addictive pain medicine, saying Mangino’s work was not in accordance with the acceptable standards of the pain medicine profession, according to deputy state attorney general Jeff Baxter.

Tennant testified that pain management medicine has evolved within the past 10 years and standards have been developed to evaluate it.

“Some doctors have raised their hands and said they want to get into this,” he said.

According to Tennant, opioids — narcotics including oxycodone — are the backbone of chronic pain management for people “on the athletic field, on the battlefield and in the clinic.”

Tennant, a founder of the American Society of Addiction Medicine, said the standards are that a doctor has to believe the patient and provide enough relief for the pain without sedating or impairing the patient.

He defined chronic pain as acute pain lasting more than three months, and that “opioids are the way to go when the other things are not working.

“Pain itself is a deadly disease,” Tennant said, noting it can cause detrimental hormone changes in the brain, spinal cord and adrenal glands.

“People with acute pain start rusting out from the inside if they don’t get pain relief, and it’s important to treat pain,” he said.

Tennant said the state board of medicine pain management standards were developed in 1985 in California by the California Board of Addictive Medicine while he was a member of the board.

“We wanted doctors to keep good records if they were going to prescribe medicine,” he said.

Tennant viewed files of 11 of Mangino’s patients and commented that the guidelines for pain management “were quite well followed. I felt the records were well up to the standards and met the regulations.