Massey University associate professor Andrew Worth confirmed that the police dog had a degenerative cyst close to the spine.
"The spinal cord doesn't tolerate any kind of bruising or insult without significant consequences. If we had done nothing he probably would have ended up paralysed.
"The surgery has set him back but we're hoping he can regain the function he's lost and a big part of that is the rehab."
Warren said Dirk had been doing hydrotherapy, where he was placed into a water-tank with a treadmill used to strengthen his muscles and help with recovery.
"Things were looking pretty grim three weeks after surgery, he was totally paralysed and wasn't getting any feeling back in his rear end, so we just lived and hoped.
"Then from the three-week period he started to show the necessary signs which gave us hope that he was going to recover."
Warren said Dirk's recovery was thanks to the "amazing team" at Massey University.
"From Andrew the head surgeon who diagnosed him, to the staff who operated on him, the nurses, physios, office staff, they've just taken Dirk on as one of their own, and he's fallen in love with the place and they've fallen in love with him and just treated him like a king."
Head of the Hawke's Bay Dog Handling Unit Sergeant Bill Birrell said it was always distressing for dog handlers to see their canines suffering.
"Dirk is still young in the police force, he's only four and a half years old, but his work is outstanding and we're definitely not giving up on him yet.
"These dogs do a great service to the community, so we do what we can within reason. He's still worth the effort, we're not pulling the plug on him yet.
"For a handler that works the dog, it's devastating because the dog was working to an extremely high standard and it makes our job that much easier."
Birrell was pleased Dirk was making good progress and said they would assess options depending on his rehabilitation progress in the coming weeks.
