Blood test results after a road traffic collision

So a few months ago I was involved in a car crash which left me with a broken knee and femur. I was given morphine and ketamine at the scene for pain relief and to help the paramedics/ fire birgade get me out of the car safely.

When I got to the hospital a Garda was there to take a blood test, I got a letter a few days later saying there was nothing in my system.

Fast forward to last week when I got a registered letter with my official blood test results stating that I had morphine in my system.

This was obviously the morphine the paramedics give me but I am curious why the Ketamine didn't show up on the results?

Is this not a tested for drug ?