Junk food and fatty treats are fuelling a "tragic" obesity crisis for British pets, new research has shown.
Owners are giving more than 10 million animals high-calorie foods including take-aways, biscuits, chips and even alcohol, according to the People's Dispensary for Sick Animals (PDSA) charity.
Around nine out of ten (87%) give pets treats, despite the fact that 91% realise the resulting obesity can reduce their pet's lifespan.
It means that of the UK's estimated 18 million pets some 2.5 million dogs (one in three) and over two million cats (one in four) are currently overweight, the PDSA claimed.
The charity said it was due to owners sharing their own unhealthy eating habits with their pets in a "well-intentioned but misguided attempt to make them happy".
Elaine Pendlebury, PDSA senior veterinary surgeon, said: "Sadly, seeing morbidly obese pets is now an everyday occurrence in vet practices across the UK; it is one of the biggest welfare concerns facing the nation's pets.
"It's effectively a silent killer leading to long term health issues for pets that can cut their lifespan by up to two years.
"Pet obesity significantly increases the danger of developing major health problems such as diabetes, arthritis and heart disease and can also bring about the onset of these chronic diseases much earlier.
"It's tragic to think that millions of pets are suffering under the strain of carrying too much weight, when it is an entirely preventable condition."
Pets in Scotland were the worst affected, with 72% of owners admitting that they give their animals unsuitable junk food, followed by animals in Wales (69%) and the North West (64%)
The survey of 2,078 pet owners found that Londoners scored the best, but almost half (48%) continue to over-indulge their dogs, cats and rabbits.
To tackle the problem, the charity is today announcing its annual PDSA Pet Fit Club, which has been running for the last eight years.
Dr Philippa Yam, leading animal obesity expert at the School of Veterinary Medicine, University of Glasgow, said: "PDSA's findings are very worrying and demonstrate that diet remains one of the most misunderstood welfare needs for pets.
"Obesity is one of the most pressing health issues affecting companion animals. PDSA's work in this area is hugely successful.
"I am delighted to see that Pet Fit Club is continuing to make a real impact on pet obesity, by raising awareness of the issue and helping to transform the lives of many pets who were heading for an early grave due to the severity of their weight problems.
"PDSA's programme clearly demonstrates that with tailored veterinary support and education, this devastating condition can be reversed."