An organization of physicians who oppose cruelty to animals is asking for an investigation of two incidents in recent years in which Marines allegedly conducted "live tissue" medical training on animals without proper authorization, saying it's time for the military to do away with this form of training entirely.

The Physicians Committee for Responsible Medicine, a non-profit advocacy organization founded in 1985, sent a letter to the Medical Inspector General of the U.S. Navy Bureau of Medicine and the Inspector General of Naval Surface Force Pacific Fleet on Jan. 11, asking that the oversight authorities investigate with an eye to finding alternatives.

According to email exchanges obtained by a Freedom of Information Act Request and reviewed by Military.com, the training in question took place during the 2016 iteration of the amphibious exercise Dawn Blitz.

Members of the 11th Marine Expeditionary Unit used two pigs to conduct live tissue training (LTT), which involves intentionally wounding or even dismembering the animals in order to practice administering medical aid. The pigs were then flown to the amphibious transport dock USS Somerset. One died en route to the ship.

The emails, which include those from the Navy surgeons for I Marine Expeditionary Force and Naval Surface Force Pacific Fleet, detail concern about whether the shipboard training was approved via proper channels, particularly because LTT is so high profile by nature.

"Apparently, [LTT was conducted] on at least two of our ships without my knowledge and without [Navy Bureau of Medicine] approval," the force surgeon for SurfPac wrote in an email. "... I am told a report is done to Congress each year on use of LTT due to its high visibility and sensitivity and this will need to be reported as an unauthorized LTT."

Emails reveal LTT was conducted under similar conditions during Dawn Blitz the previous year.

In a letter signed by Dr. John Pippin, director of academic affairs for The Physicians Committee for Responsible Medicine, the group calls for investigation of the alleged unauthorized training.

But Pippin told Military.com the group's real concern is the continued use of LTT in any capacity.

The letter mentioned the existence of hyper-realistic "cut suits" that can be worn by a human actor and made to simulate a wide range of wounds and injuries, and other simulation aids that can offer realism in combat trauma training.

"There are better ways to do this now, and that has not permeated certain elements, including elements of the Department of Defense," Pippin said. "Our impetus for doing this is to improve combat trauma training [using] non-animal or human-relevant methods."

A spokesman for SurfPac, Doug Sayers, told Military.com that the letter had been received and an initial review of its contents was underway.

Like the rest of the military, the Marine Corps has been moving away from live tissue training in recent years.

LTT has been prohibited aboard Marine Corps Installations since 2014, said Marine Corps spokesman Capt. Christopher Harrison. However, he said, units can still work with vendors who meet military and Navy requirements to conduct LTT at off-base locations.

Those requirements, he said, include regular accreditation from the Association for the Assessment and Accreditation of Laboratory Animal Care.

"Any LTT event has stringent requirements to be conducted, including approval from BUMED (as the Component Animal Use Oversight Office for the Navy and Marine Corps) and the presence of experienced veterinary staff to support and monitor the animals to prevent them from experiencing pain or distress," he said.

Officials with I MEF said the command is currently making investments into quality alternatives to LTT.

Lt. Col. Christopher Perrine, director of communication strategy and operations for I MEF, said a casualty care simulation working group had been created in January 2017, with a simulation training program launched in October 2017.

There's now a monthly five-day training course, he said, that uses "organic, high-fidelity" simulators to test competency in casualty care.

"The MEF has purchased two dozen combat simulators at a cost of $1.2 million," Perrine said in a statement. "The training is hyper-realistic, and priority goes to those who are scheduled to deploy."

Once considered a necessity for realistic triage training, use of live animals has fallen dramatically out of favor with the military in the last five years, due in large part to Pentagon reforms.

In 2017, the Coast Guard announced it was suspending its use of the training, a practice commandant Adm. Paul Zukunft called "abhorrent."

-- Hope Hodge Seck can be reached at hope.seck@military.com. Follow her on Twitter at @HopeSeck.