The PDSA charity says a large number of pet owners in Wales and across the UK aren't feeding their animals the right diet.
The organisation warns that a poor diet combined with a lack of exercise could lead to reduced life expectancy in a pet.
Pet obesity poses not only major health risks such as diabetes, arthritis and heart disease, but sadly also means daily misery for millions of pets who are feeling the strain from carrying too much weight.
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Stars of Team GB at this years' Olympics were in Wales today, as part of ITV's I Am Team GB campaign.
As Wales gets involved in the country's biggest sports day - Our Olympians have been getting in on the action.
ITV switched off all of its channels for an hour on Saturday as part of a national sports day event.