White coats show everything. Grass, mud, saliva on the paws a dog has been chewing, the rusty shadow under the eyes and around the mouth, and all of it builds up gradually enough that owners often do not see how dull a coat has gone until it is washed properly. A brightening shampoo works on that staining specifically rather than just cleaning, which is why groomers keep a separate bottle for the pale dogs on the books instead of using one shampoo for everything.

This is a professional concentrate, diluted fifteen parts water to one part shampoo, so a small bottle goes a very long way and the 5-litre works out cheaper still for a multi-dog household or a grooming room. The blend carries cucumber, passion flower, lemon and lime extracts, which condition as the shampoo lifts the dirt, and that matters on a white coat because harsh cleaning leaves the hair dull and coarse, undoing the brightness you were trying to get in the first place.

• Formulated for white and light-coloured coats
• Targets dirt and staining rather than just washing
• Cucumber, passion flower, lemon and lime extracts
• Professional high-concentrate formula, dilute 15:1
• Three sizes: 250ml, 500ml and 5 litres

On what brightening can and cannot fix. It lifts staining out of the coat. It does nothing about the cause of tear staining, which sits in the eye rather than the fur, so a dog whose eyes run constantly needs a vet appointment as well as a bath. Dilute it properly, too, because neat concentrate is wasteful and leaves residue.

What the options mean. Sold in sizes from 250ml to 5 Litres — £7.49 to £27.99.

Who it's for: Owners of white and pale-coated dogs, and groomers who want a stain-lifting shampoo that keeps working out cheaply.