Traffic had to be slowed by rolling roadblocks several times along the M1 on Monday morning after a dog was spotted on the central reservation.
It was feared that the Staffordshire bull terrier would run into the busy motorway causing a major accident between Junction 9 and Junction 10.
A spokesman for the Highways Agency said: “It was quite a frustrating one because we kept on spotting this dog in the central reservation and it kept on disappearing and then reappearing.”
Flashing road signs were also put into action to warn drivers as attempts were made to rescue the animal.
The dog ran off into a neighbouring field and was later found by two people who handed the animal over to the Dacorum dog warden. The pet has since been reunited with its owner.
The highways spokesman said: “It had a happy ending.”