Wales has become the first part of the UK to outlaw the use of electric shock collars to train cats and dogs.
The ban, passed by assembly members, means from midnight anyone caught using the devices faces a fine of up to £20,000 or six months in prison.
Animal welfare groups such as the RSPCA and the Kennel Club supported the move.
The Electronic Collar Manufacturers’ Association said it feared the ban could lead to an influx of unmanageable pets into dog shelters.
The collars are sometimes used to train dogs and cats by giving an electric shock when the animal is deemed to have behaved badly.
Wales’ Rural Affairs Minister Elin Jones, who announced plans for the ban last month, said she was “very pleased”.
“It is important that owners are aware of the ban, and that they now take appropriate steps to comply with the law,” she added.