A man attacked three police officers and a police dog after being asked if his journey was essential during the coronavirus lockdown - in what has been called a "truly horrifying" incident.
Nelson Nelson, 29, struck the canine several times with a plank of wood with nails in it during the "violent rampage" on Saturday.
British Transport Police (BTP) said two of their officers had been on patrol at Nottingham train station when they noticed Nelson trying to board a train.
They asked him if his journey was definitely needed and he then became abusive and threatened to "knock them out", according to the force.
He was refused travel and taken out of the station where he punched the officers in the face and they both fell to the ground, one becoming unconscious.
Nelson was then chased by the other officer and Nottinghamshire Police officers managed to find him before the attacker charged at an officer and punched him.
Nelson, from Aldridge in Walsall, then struck the canine with the wood, cutting the dog's chin, before being arrested.
BTP said he was found to be carrying a knife.
The force said their two officers were taken to hospital.
One had severe concussion and bruising to her face, while the other suffered ligament damage to his jaw and thumb, as well as bruising and swelling across his body.
The Nottinghamshire Police officer and police dog were not seriously injured and did not need treatment.
The four-year-old canine, named Quantum, nearly died in another attack two years ago when he was stabbed by an offender, police say.
At Nottingham Magistrates' Court, Nelson pleaded guilty to two counts of actual bodily harm, assault with intent to resist arrest, assault of an emergency worker, possession of an offensive weapon, possession of a bladed article and causing unnecessary suffering to a protected animal.
Magistrates sent the case to the Crown Court as they felt the case was too serious for their sentencing powers.
British Transport Police Chief Inspector Gareth Davies called the incident "truly horrifying".
"There is never an excuse for this sort of behaviour, but it's all the more shocking to think this violent rampage began after Nelson was simply asked if his journey was essential," he said.
"Thankfully, no one was more seriously injured, and the officers involved are receiving the support they need."
Chief Constable Craig Guildford of Nottinghamshire Police said it was a "particularly nasty case" involving a vicious and sustained assault.
"The officers acted swiftly, bravely and decisively in assisting their British Transport Police colleagues and I'm convinced PD Quantum prevented further serious injury to them or the public," he said.
Nelson has been remanded in custody and is due to be sentenced on 27 April.