Millions of pets are more aggressive, overweight and misunderstood due to a lack of welfare knowledge among owners, according to the PDSA.
The charity found 1.3 million dogs across the UK are demonstrating problem behaviour, while 18.5 million dogs, cats and rabbits are not being given the right pet food and are instead receiving a diet that could be deadly to them.
In addition, a lack of understanding about vaccination and neutering means 11.2 million pets are also at risk of life-threatening disease, the PDSA suggests.
The organisation's second PDSA Animal Wellbeing (PAW) Report canvassed the views of owners, vets and children to expose the most problematic welfare issues domestic animals in the UK are facing.
"The new report identifies serious concerns when it comes to the wellbeing of our pet nation, but in reality these are just the tip of the iceberg, especially if we don’t take action now to protect animal welfare long into the future. Taking on pets is a huge commitment and one that brings with it significant responsibilities throughout a pet’s lifetime, " said PDSA head of pet health and welfare Nicola Martin.
Click here to read about the findings in more detail.