The 68-year-old younger man was allegedly spat and punched in the face of a popular dog walking trail in north Brisbane.
Queensland police are investigating a "serious attack" on the Sandgate coast, on the city's coast, between 7 and 7:30 today.
The woman was allegedly injured during a feud over a man's dog.
"The man allegedly spat on the woman and punched her in the face, causing the woman to lose consciousness and fall to the ground," police said in a statement Tuesday.
The alleged offender was described as being in his 30s, Caucasian and with an olive tone.
He was about 180 centimeters tall and wore a yellow top and dark pants without shoes.
The man was last seen walking down Second Ave with a gray American Staffordshire Terrier.
The woman was hospitalized for treatment.
Sandgate Forest includes a 6.5-mile water walk from Shorncliffe to Brighton.
Police urge that all witnesses or those who own CCTV or dashcam in the area be reported to investigators.
Information can be provided to Policelink on 131 444 or anonymously through Crime Stoppers on 1800 333 000.