Red Bluff Police said the attack happened at 6:49 a.m. on the 600 block of Givens Road.
When officers arrived on scene they found 56 year-old Michael Carrel lying in a pool of blood near the roadway.
During an investigation officers learned Carrel had been walking his dog on Givens Road when a bicyclist passed him.
Carrel's dog barked at the man on the bike, which cause the man to use profanities at him.
Carrel said he then questioned the man about his use of profanities.
The man then allegedly struck Carrel with an unknown object and fled the scene.
Carrel lost consciousness for a short period.
A nearby witness called 911 and reported the attack.
Carrel was transported to the hospital where he was admitted for head trauma.
The suspect is described as a white adult male, gray hair and was riding a large mountain bike.
Anyone with information is asked to call Red Bluff Police.