The incident happened in the Sir Walter Scott Drive area of Inverness at around 12 noon today, police said.
The 51-year-old was taken to the city's Raigmore Hospital for treatment and his injuries are not thought to be life threatening.
Officers closed the road for around 30 minutes as police dog handlers controlled the dog, which had to be humanely euthanised at the scene.
It is thought to be a mixed breed Staffordshire bull terrier and American Bulldog.
Police are appealing for any witnesses to the incident to contact them.