Andrew George McDaniel, 51, launched the bizarre road rage attack near Eyre River, 20 minutes north of Christchurch, about 5.45pm on March 23.
McDaniel was driving a Nissan 4WD when a father-of-two out walking with his family and 10-month-old puppy signalled that he should slow down as he exited the Eyre River - popular with off-road enthusiasts - crossing on to Downs Rd.
The property developer took offence at the caution and tried to run him down.
The father was hit by the 4WD before diving to safety over a barbed wire fence.
The dog had to be put down due to its severe injuries, police said.
The man was treated at Christchurch Hospital for cuts to his hands, cuts and bruises on his head and injuries to his shoulder and ankle.
He has since been released and is recovering at home. No other members of his family were hurt.
After his arrest, McDaniel, from Swannanoa in North Canterbury was remanded in custody at a psychiatric hospital to assess his mental health.
Psychiatric reports, prepared under the Criminal Procedures (Mentally Impaired Persons) Act, found that he was fit to enter pleas.
Today, through defence counsel Michael Starling, he pleaded guilty to charges of injuring with intent to cause grievous bodily harm and willful ill treatment of an animal. He also admitted unrelated charges of assault, drink driving and careless driving.
Judge Chris Sygrove remanded McDaniel in custody to Hillmorton Hospital and asked for a psychiatric report to be prepared ahead of sentencing on December 15.