The Royal Society for the Prevention of Cruelty to Animals says that one in three pets are overweight and that the makers of pet food are partly to blame.

The charity says the recommended servings printed on the side of cat and dog food tins are pitched at the highest end of the acceptable scale.

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It is also warning about the proliferation of high calorie, fatty pet snacks - saying there are now more than 500 varieties on the market.

The RSPCA wants pet food companies to put lower recommended daily servings on their tins.

It also wants owners to be more aware of the dangers of overfeeding pets.

It warns that dried pet food is a particular danger - often owners do not realise how dense the product is and put too much in their pet's bowl.

Overweight pets at risk

There are an estimated four million overweight cats and dogs in England and Wales.

The RSPCA says animals that have become too fat are at risk of developing crippling, or even life-threatening, illnesses.

The Pet Food Manufacturers' Association says it accepts that there are too many overweight pets in the UK.

But the association denies that members' labelling is in any way irresponsible.