The survey of veterinary surgeries, carried out by scales manufacturer Marsden, asked what percentage of cats and dogs they saw were overweight. The average was 58 per cent - although the ratio reported by one practice was as large as four in five.
Most vets recommended monthly weighing of animals, although some suggested twice a month - especially if the animal was already overweight.
However, almost all of those surveyed said that owners only weighed their pets just once a year - at the vets.
Anita Dowe, of Abivale Veterinary Group in Oxfordshire, said: “Pet obesity is a tricky topic to tackle with owners. Often they don’t feel there is a problem, and it can be difficult to get them to understand the nasty consequences of obesity in their pet.
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“There is also often a strong emotional association with feeding and owners ‘feel bad’ not giving them treats.”
“I feel the biggest causes of pet obesity are simply owners overfeeding their pets, owners not realising there are different feeding guides for different foods, owners not realising how quickly the calories start to pile up when giving a treat here or there, and also owners not thinking their pet is overweight to begin with.”