People who are considering investing in pet toys and food for an animal can do so online, but when it comes to buying the pet they should stay away from the internet.
Battersea Dogs & Cats Home is set to launch a campaign to warn prospective owners about buying online, reports the Press Association.
It is looking to stop sellers breeding irresponsibly to make money by obtaining more regulation of websites such as Gumtree and Facebook.
Liz McWalter, head of intake at the charity, told the news provider: "A quick search on the internet reveals just how easy it is to buy a pet cheaply and quickly without giving any real thought to the life-changing decision you are making.
"We need to see much stricter guidelines on the sale of pets online to prevent thousands more dogs and cats ending up mistreated or abandoned."
Last year, Battersea cared for 6,917 dogs and 2,742 cats and managed to rehome 2,821 dogs and 2,241 cats.