Fat dogs and cats could become common place in the UK if owners do not radically change their habits, according to a report from a leading animal charity.

The annual PDSA Animal Wellbeing (PAW) report showed a "shocking" rise in dog aggression, which the animal experts say is fuelled by a "cocktail of boredom, lack of training and socialisation and worryingly low levels of regular exercise".

Rescue dog Jack, a King Charles Cavalier, was adopted by Rose Welch, who met him the night vets thought he might die from obesity.

The report, which is the largest ever annual assessment of pet welfare, found 80% of vets and nurses predicted the number of overweight pets would overtake the amount of health cats and dogs in the next five years.

Some 5.5 million British pets are fed fatty treats and this taking a long-term toll on their health, vets warn.

Poor diets are made worse by a lack of exercise, the report warned. Some 2.4 million dogs in the UK are not given the opportunity to safely exercise off the lead outside the home or garden on a daily basis, with more than 800,000 pooches never going for walks at all. The PDSA said that this can lead to destructive behaviour and anxiety, as well as aggression and obesity.

And it said a quarter of a million dogs are behaving aggressively towards people every week with more than 600,000 dogs a week showing hostility towards other pets.

Among the other findings of the report are:

• 1.5 million dogs are not properly "socialised" as puppies - which involves exposing them to everyday sights and sounds before 12 weeks of age.
• 62% of pet owners have been concerned or frightened by another dog's behaviour
• 30% of pet owners report they have been bitten or attacked by a dog
• Over half of veterinary professionals report an increase in levels of dog on dog attacks
• Owners over 55 are least likely to seek vet advice regarding their pet's diet.
• Just 66% of dog owners are aware that microchipping will soon be compulsory in England and Wales
• Five million pet owners did no research at all before taking on their pet with many largely unaware of the specific needs of their chosen pet
• 25% of pet owners would consider getting a puppy from a puppy farm where there welfare needs are unlikely to have been properly met