Circus elephants are undergoing blood and urine tests amid suspicions their food could have been tampered with after one of the animals toppled on to a worker.
Justino Munios remained in critical condition in hospital last night following the incident on Saturday evening.
The circus worker, who is in his 30s, was brought to Cork University Hospital after what Courtney Brothers Circus described as "a freak accident", which happened as the man was feeding hay to the elephants.
Last night, Mr Munios remained in intensive care, with a garda spokesman saying his condition had worsened.
According to one eyewitness, two of the circus elephants knocked off each other, causing one to collapse on Mr Munios, temporarily crushing him on a concrete floor.
The witness said he didn't believe the elephants' behaviour was unduly aggressive.
Courtney Brothers Circus asked for blood tests to be carried out on its elephants yesterday, saying it had suspicions the elephants' food had been "tampered with".
The freak accident followed an incident earlier in the week when one of the elephants, 'Baby', got away from its handler Joy Gartner and dashed through a nearby supermarket car park.
"To have one incident like this in a week is extremely rare," said circus general manager Wayne Courtney, "but to have two means we have our suspicions that someone may have tampered with the elephants' food.
"We requested that a vet come onsite this morning to take blood and urine samples and we will also provide them with samples of the elephants' food."
Gardai said they were not currently probing the accident while the Health and Safety Authority said it would investigate if the incident was reported as a workplace accident.
There have been daily demonstrations outside the circus by animal rights activists during its Cork run.
"These are not dangerous animals," said their handler Mr Gartner. "I let my own son play with them. It's something I would not do unless I was 100pc sure of his safety.
"It was just an unfortunate accident and we all hope that Justino can leave hospital soon."
A member of South Doc After Hours Medical Service who witnessed the event said: "I thought for a second it was part of the show.
"I happened to be looking at the elephants at the time, and from what I could see there was no threatening behaviour, two elephants just bumped off each other and one fell over.
"It was back on its feet in a couple of seconds."
Animal Rights Action Network earlier warned that the incident involving the elephant represents "a wake-up call" for the public over large, wild animals being part of Irish circuses.