The What Makes You Beautiful hitmakers launched their North American shows in June (13) and they spent two months on the road before finally heading back to Britain in early August (13).
Malik has now revealed he purchased a puppy while they were in the States, and he took it along on the band's tour bus.
However, the dog, which he has named Harley, wasn't properly house-trained and had several accidents onboard the coach.
The singer tells Britain's The Sun, "What did management say?... Erm yeah (they were not impressed)... The boys love him, although he pooed on the bus when I wasn't there recently. It stunk it out and Louis (Tomlinson) stepped in it. He had socks on, but he wasn't too happy."
Malik has been forced to leave Harley in the U.S., but hopes to have his paperwork sorted out soon so he can bring him back to the U.K.
He adds, "He's only nine weeks old. I need to get him chipped and back to the U.K."