Guthrie said an ambulance was called straight away, and a couple of off-duty nurses helped keep the boy still and wrapped up in blankets.
He was initially in a lot of pain, and as time went on he started to go into shock.
"After several calls, it [the ambulance] finally turned up about an hour and a-half later."
The boy was taken to Dunedin Hospital in a moderate condition at 12.27pm — 1 hour and 32 minutes after the initial 111 call.
Guthrie said the boy was admitted to the emergency department and released from hospital on Saturday evening.
"I'm pretty disgusted in the service.
"Is that a realistic amount of time in today's world, that we should be waiting for an ambulance?
"Given his potential injuries, I would have thought he would have been given more priority than that."
Guthrie said he respected St John's ambulance officers and emergency call-takers.
His main concern was with the inadequate funding that New Zealand's ambulance service received.
"I can't understand why our ambulance service still isn't government-funded properly.
"St John do a great job. You've just got to get them there."
St John coastal Otago territory manager Doug Third, of Dunedin, confirmed St John responded to the incident and said the boy's injuries were categorised as "not immediately life-threatening".
A clinical support officer continually reviewed the case and spoke to the patient's support person, but it remained not immediately life-threatening, he said.
"All available ambulances in the area were committed to potentially life-threatening, time-critical medical emergencies."
Third said St John was experiencing high demand for ambulance services across the country and workload last month was the highest it had ever been.
When all available crews were committed, patients not in a life-threatening condition often had to wait longer.
"We understand this can be frustrating for patients and their support persons, but it is the right approach to prioritise the most urgent and time-critical patients."
As part of this year's Budget, St John received funding for additional frontline support, including an extra ambulance to support Mosgiel, Dunedin and South Otago, Third said.
The new ambulance starts service in December and would operate 18 hours a day, seven days a week.
St John would also be employing six new ambulance officers in Dunedin, he said.