The dog was eventually caught with no harm done to any of the riders, and Van der Poel went on to win the race.
Video footage surfaced of the stray dog, with a leash still hanging from its collar, running alongside the riders during the elite men's race as they passed through the finishing straight at the end of the first lap.
Tom Pidcock (Trinity Racing) was leading the race followed by Quinten Hermans (Telenet-Baloise), and then a small gap to chasing riders Eli Iserbyt (Pauwels Sauzen-Bingoal) and Van der Poel.
The dog was first seen running behind the two leaders Pidcock and Hermans, but it looked to give up its chase, until Iserbyt and Van der Poel then passed through the straightaway.
The dog was then seen chasing Van der Poel's back wheel as he tried to sprint away from it through the finish line at the start of the second lap.
Several people including a course marshal tried to catch the dog through the finish line, but were unsuccessful. The dog continued chasing riders into the first few hundred metres of the course and caused one rider to stop and unclip from his pedals.
Van der Poel ended up winning the race ahead of Pidcock and Hermans.