A woman was verbally abused and assaulted by another dog walker while in a field near Badby.
The assault happened on Saturday, January 5, at about 11.15am on a footpath that runs through a field off the A361, next to the layby shortly before the village of Badby, coming from the direction of Daventry.
A man, who was also walking his dog, approached the woman and shouted verbal abuse before assaulting her.
Two people shouted from a distance and the man ran off with his dog.
The man is described as white, about 5ft 11in, stocky and about 50 years old.
He was wearing a blue jacket, black body warmer and blue jeans, and a beanie-style hat with a peak.
He had a light stubble beard and was walking a black long-haired Alsatian.
Officers are appealing for witnesses and would particularly like to speak to the couple who shouted and are believed to have seen the assault.
Anyone with information should call Northamptonshire Police on 101. Alternatively, they can contact Crimestoppers anonymously on 0800 555111.