A Perth man who stabbed a kangaroo more than 20 times with a knife in a "brutal and savage" attack will spend five months in jail.

Key points: Swan chased the "terrified" kangaroo down as it tried to escape

Swan chased the "terrified" kangaroo down as it tried to escape He said he was disgusted by the incident and could not say what had come over him

He said he was disgusted by the incident and could not say what had come over him He has lost his job and separated from his partner as a result of the attack

Ricky Ian Swan, 28, previously pleaded guilty to two animal cruelty charges.

Warning: This story contains content that may be distressing for some readers.

Swan was handed an immediate jail 12-month jail term, seven months of which was suspended, in the Joondalup Magistrates Court today.

He was also given a $3,000 fine for being in possession of a knife with intent to inflict cruelty.

He was one of four men charged in September with using a number of weapons to fatally torture two kangaroos in May and June, in an attack filmed and later posted on social media.

Magistrate Deen Potter said the kangaroo must have been terrified.

"You subjected this particular animal to a savage and brutal attack," he told Swan.

Mr Potter said Swan had chased the "clearly distressed" kangaroo down.

It tried to escape but Swan stabbed it in the back of the neck as it lay on the ground struggling.

He then attacked it again "in a frenzy", inflicting another 20 stab wounds.

Swearing profusely at the dying animal, Swan then stepped back and kicked it in the head before spitting on it.

John Hammond (left) said his client Swan (right) was distressed at the sentence. ( ABC News: David Weber )

'I don't know what came over me'

Mr Potter said the definition of cruelty to an animal included torture, mutilation and malicious behaviour, and Swan had acted in all these ways.

He said the only effective public deterrent involved a term of imprisonment.

But the magistrate took into account Swan's early guilty plea, the fact he had handed himself in to police, his struggle over the death of his father and the fact he had sought counselling to better understand his behaviour.

In one of his sentencing reports, Swan said:

"I don't know what came over me. It's disgusting. That person in the video is not me."

He has since separated from his fiance and lost his job because of his crime.

Mr Potter did not accept his actions were the result of excessive drinking at the time and said the fact he had a knife showed a level of pre-planning.

Jehni Thomas-Worth and Animal Justice Party supporters called for a jail term for the attack. ( ABC News: David Weber )

Swan's lawyer, John Hammond, told the court the public backlash against his client had made him a "pariah in the community".

He said while Swan was the principal offender, he had no prior convictions.

This was unlike one of his co-accused Luke Kevin Dempster, who this week was sentenced to two years in jail for a string of "monstrous" animal cruelty offences — including bashing a kangaroo with knuckle dusters and torturing a chicken — as well as assault, firearms and drug offences.

Mr Potter said Dempster had incited Swan to carry out the attack.

Outside court, Mr Hammond said Swan was "distressed" by the sentence.