Carr & Day & Martin Gallop Stain Removing Shampoo 
Gallop Stain Removing Shampoo is an extra thick, concentrated, purple formula with powerful stain removing properties to enable you to remove the most stubborn and ingrained grass and stable stains. Ideal for light coloured horses and problem areas such as knees and hocks. Cleans whiter than white – even removes manure yellowing, yet still kind on sensitive skin.
Apply directly to a wet coat. Work in well with a brush, sponge or by hand to produce a good lather, then rinse thoroughly. For problem areas, such as hocks and knees repeat the process.