A 74-year-old man was thrown to the floor and repeatedly kicked by youths as he walked his dog in Heckmondwike.
The attack took place on the Spen Valley Greenway near Wormald Street on Thursday evening and the pensioner suffered broken ribs.
The man's wife, who wished for them both to remain anonymous, said that he had been verbally abused before being struck from behind and beaten.
She said: "He was wandering down the path and our dog walked towards two lads who were sat on the banking with their bikes.
"The dog just sniffed at their bikes for a second or two, and they started swearing at him.
"My husband told them where to go, walked away and suddenly he was hit from behind.
"He grappled one of the lads and the other pushed him to the ground. Then he was kicked and kicked over and over."
The victim was taken to Dewsbury Hospital for treatment and is now recovering at home.
"He's shaken up by it and he didn't have a good night last night," his wife said today (Monday), "he's in a lot of pain and he's on some strong painkillers. He just can't move."
A West Yorkshire Police spokesperson said: "Police are investigating after a 74-year-old man was the victim of an assault near Spen Valley Greenway on Thursday afternoon.
"The victim was walking his dog on Spen Valley Greenway at around 5pm on Thursday when his dog approached two males on bikes. There has been a verbal altercation before the victim has walked away onto Melbourne Street. The males followed him and assaulted him, resulting in the pensioner suffering a broken rib.
"The suspects are described as Asian males, wearing dark clothing.
"Anyone who witnessed any part of this incident or who may have information about the males involved is asked to call Kirklees police via 101, quoting crime reference 13190056987. Information can also be given by using the Live Chat facility on the West Yorkshire Police website."