Up to 40% of domestic pet dogs in Europe could be overweight or clinically obese, according to veterinarians; some US vets say the figures are very much higher. It is a hidden problem for many owners -- they simply do not realise that their dog is heavier than it should be. UK practitioner Andy Green from the Pennard Veterinary Practice in Kent says: "They are not aware of gradual weight gain until they bring their dogs in for check-ups and see over time how much their dog has gained weight." Excessive weight can shorten a dog's life by up to two years, impair its quality of life, and contribute to medical problems such as heart and lung disease, arthritis and joint problems, as well as diabetes. Owners who are concerned about their dog's weight are being encouraged to visit the vet. Vets say that excessive weight is a clinical issue; owners are usually advised to reduce the animal's weight, through a combination of exercise and diet. For those dogs,...