Hill's Prescription Diet Metabolic + Mobility Dog Food review

Ingredients, as declared: Cereals, derivatives of vegetable origin, vegetable protein extracts, meat and animal derivatives (chicken 6%), seeds, vegetables, oils and fats (fish oil 2.3%), minerals, molluscs and crustaceans.

The list runs in categories. Cereals, derivatives of vegetable origin and vegetable protein extracts take the first three places, and the meat follows as meat and animal derivatives with chicken declared at 6%. Seeds, vegetables, oils and fats, minerals, and molluscs and crustaceans complete it.

Two entries carry the joint side of the pitch. Fish oil is pulled out of the fats and printed at 2.3%, and molluscs and crustaceans sit at the tail of the list. Glucosamine usually comes from shellfish shell in the trade, and that is its job in a recipe of this sort. Neither entry is described any further on the packet.

For an owner keeping track of ingredients, that puts chicken, fish and shellfish in the same bowl while the rest of the label stays at category level. It is worth a look before you start the bag if shellfish or fish is off your dog's list. The practice that recommended the diet can tell you how much room there is to move.

Protein is declared at 26.1% and fat at 12.6%, converting to 28.4% and 13.7% of dry matter. Crude fibre is 14.2%, or 15.4% once moisture is stripped out, and the carbohydrate estimate is 36.8% of dry matter. Energy works out at 315 kcal per 100g. High fibre with restrained energy is how a diet aimed at bodyweight is built, not a sign that something has been left out of it.

The mineral panel is dosed in print, with iron at 74.2mg, iodine at 1.8mg, copper at 7.3mg, manganese at 7.7mg, zinc at 130mg and selenium at 0.2mg, finished with a natural antioxidant.

Feeding on a bag like this gets set against the weight your dog is aiming at rather than the weight it is now. Ask the vet running that plan for the daily amount. They can also say whether a diet covering two problems together is the right call for your dog.

The bags run 1.5kg, 4kg and 12kg, at £5.57 a kilo. On the basis of a 15kg dog eating 266 grams a day, that is roughly £1.48 of food a day.