Almost every flea product works somewhere you cannot watch: in the coat, over weeks, on a life cycle you have to take on trust. A bath is the exception. You get the dog wet, you work it in, and what comes off into the water is the only direct evidence anybody ever gets.

This is a veterinary medicinal shampoo containing permethrin. Beaphar say it kills fleas fast and helps stop reinfestation while cleansing the coat. Their instruction does not stop at the dog, though: fleas settle in the basket, the bedding, the carpets and the soft furnishings, so Beaphar recommend treating those areas with a household insecticide and vacuuming them regularly alongside the bath. The bottle is 250ML and it is cleared for dogs over 12 weeks of age.

• 250ML bottle
• Contains permethrin
• Cleared for dogs over 12 weeks of age
• Beaphar print DO NOT USE ON CATS on the label
• Beaphar advise treating bedding and soft furnishings at the same time
• A veterinary medicinal product

Read the capital letters before you read anything on this page. Beaphar's own label says DO NOT USE ON CATS, and in a household with both animals that is a handling decision rather than a footnote — where the dog dries, who handles it afterwards and what the cat sleeps on all follow from it. The dilution, the contact time, how often it may be repeated and what to do if it reaches the eyes are all on the bottle and none of them have been supplied to us, so the label is the document to work from. Worth being clear on what a bath is, too: it deals with the animal in front of you at that moment and is not a month of cover.

Who it's for: owners of a dog over twelve weeks who want to deal with what is on the coat today, in a house where a cat can reliably be kept clear of it.