LONDON -- Britain's general election was going to the dogs Thursday as voters took their pooches to polling stations up and down the country.

Prime Minister Boris Johnson set the tone early when he took his Jack Russell cross Dilyn with him as he voted in London.

The city's mayor, Sadiq Khan, followed Johnson's lead, posting a video of himself and his dog Luna at a polling station and urging people to vote.

By early afternoon #dogsatpollingstations was trending on Twitter as owners followed suit.

Photos showed dogs dressed up in costumes varying from a bumble bee to Santa Claus sitting next to polling station signs. One was festooned with festive lights, reflecting the timing of the election less than two weeks from Christmas.

It was not clear how many dogs got into voting booths. The electoral commission says animals, with the exception of assistance dogs, "are not usually allowed inside polling stations."