Tailbacks are occurring on the motorway's westbound carriageway link road with the M621 at junction 27, close to the retail park at Birstall, this afternoon.
Mandy Taylor, a member of the Charity Angels, tweeted: "Junction 27 #M62 westbound at a total standstill due to animals in the road".
She included a picture which shows a motorway sign issuing the warning.
The West Yorkshire Police Force Command Hub said: "We are getting reports of a dog on the network."
Highways England said that traffic was held due to "another loose dog" on the road, but vehicles were later released and "flowing".