Referencing the IRL Dream Journey having a serial biting habit. Most notably his jockey Ikezoe praised him as a smart boy for cornering his victims first (against a literal wall or corner) to cut off any escape routes before proceeding with the biting, to the utter disbelief of his colleagues (e.g. Yutaka, Drejour's previous jockey) and people reading the news in the JP racehorse fan community. Some of the comments back then were to the effect of "You must be crazy" and "You have a dangerous fetish (implied) there."

Which is why Trainer here seems turned on by Drejour taking a huge bite...