The present invention describes novel compounds, or veterinary or pharmaceutically acceptable salts thereof, veterinary or pharmaceutical compositions thereof, and medical uses thereof. The compounds of the invention have activity as prostaglandin EP4 receptor antagonists and are useful in the treatment or alleviation of pain, inflammation and inflammation-associated disorders. Also described herein are methods for treating pain by administering the compounds of the invention. For example, the invention describes 1-[2-[4-(2-ethyl-6, 8-dimethylimidazo[1, 2-a]pyrazin-3-yl)phenyl]ethyl]-3-(p-tolylsulfonyflurea of the formula : veterinary or pharmaceutical compositions thereof, and methods of treatment using the subject compound and compositions thereof.