A dull coat is one of the few things about a dog's diet that's actually visible day to day, which is probably why so many foods lead with a coat-and-skin promise even when the mechanism behind it is just a handful of specific nutrients rather than anything more complicated.

Hair Necessities puts Scottish salmon at 50% of the recipe (26% freshly prepared, 20% dried, plus salmon oil), with sweet potato and potato for the carbohydrate rather than rice or oats, making it grain-free. Biotin is included at 0.15mg/kg, on top of the standard vitamin and trace element pack, and the recipe carries no separate grain ingredient at all.

• Scottish salmon 50% (26% freshly prepared, 20% dried, plus salmon oil)
• Protein 24%, fat 13%, fibre 3%, ash 7.5%, 368 kcal/100g
• Grain-free recipe
• Biotin included at 0.15mg/kg
• Sweet potato and potato for the carbohydrate
• Also available in a larger bag

One thing worth knowing. Biotin at 0.15mg/kg is the specific coat-and-skin addition Barking Heads name here, but it's one nutrient among many that affect coat condition - a persistently dull or flaky coat is worth mentioning to a vet rather than assuming a food change alone will fix it.

Who it's for: owners of adult dogs who want a grain-free salmon recipe, particularly if coat condition is something you're keeping an eye on.