According to an Associated Press story on bloodhorse.com, a top Hong Kong horse trainer ridiculed a doping charge against him after officials found the banned substance in a shampoo handed out freely by track veterinarians, a newspaper reported Wednesday.

Trainer Ivan Allan attacked The Hong Kong Jockey Club’s chief veterinary surgeon, Dr. Keith Watkins, for saying a horse tested positive for the diuretic Isosorbide and saying that the drug could not have come from anything used by club vets, the South China Morning Post reported.

The horse, Cheers Hong Kong, was scratched from a race Feb. 23 as a result, but Allan complained that the diuretic is contained in a skin-rash shampoo for horses called Imaverol handed out by Watkins’ department, the newspaper said