Not knowing how to manage the internal bleeds suffered by Group One-winning sprinter The Quarterback has forced the gelding into retirement.

Trainer Robbie Griffiths says it was an easy decision for the ownership group after the seven-year-old underwent tests to determine the cause of the exercise-induced pulmonary haemorrhage (EIPH).

But the tests provided no answers so vets were unable to come up with a plan to combat the problem.

The Quarterback finished last at his two most recent starts at Flemington, beaten more than 30 lengths, after being eased down by jockey Matthew Allen.

The most recent race was at Flemington on November 9.

"After he ran so poorly on Oaks day he had an EIPH grade three, which was of a high level," Griffiths said.

"Knowing that had happened with minimal pressure because Matthew Allen eased him out, we did a series of tests on his heart and lungs.

"The experts couldn't see why that was happening and the scariest part was the experts couldn't give me a control plan.

"Once we realised it was high risk if he raced on then it was a simple decision to pull the pin.

"No trainer and ownership group minds managing an issue but when it looks as if it's not controllable, it becomes unsafe."

After a spell, The Quarterback will be looked after by his longtime strapper Leanne Fielding.

"He'll get pampered and blue-ribboned and have a good life," Griffiths said.

"Its always sad when you lose your best talent but the decision has been made for all the right reasons and we're comfortable with that."

The Quarterback, winner of the 2016 Newmarket Handicap, retired with nine wins from 34 starts and prize money of more than $1.5 million.