By Sarah Tawton
Animal welfare campaigners have set out new guidelines to protect pets advertised online.
The Pet Advertising Advisory Group (PAAG) says it has seen a number of "shocking" internet adverts.
This includes a puppy being offered as a swap for a mobile phone and a tortoise in exchange for a watch.
Up to 120,000 pet adverts appear on UK websites each day.
But the PAAG is warning that many of these online ads are putting these animals welfare at risk and leave buyers in danger of buying sick, dangerous or even illegal creatures.
Adverts spotted by the company included one person who was selling a zonkey, which is a very rare cross between a zebra and a donkey.
Other sellers offered pitbulls for sale despite it being illegal to sell this breed in the UK.
And one owner was trying to get rid of a cat in need of urgent veterinary treatment due to a badly damaged eye.
One advertisement offered a chihuahua in exchange for a golden retriever, while others were even offering an Arctic fox and four marmoset monkeys.
PAAG's new set of minimum standards is designed to help buyers make a safe and ethical choice when deciding to find a pet online.
The group, which is made up of representatives from leading animal welfare groups and specialist agencies, said it wants to remind internet users that an animal is not a commodity.
PAAG wants to make it clear to owners that pets should not be advertised or bought in the same way as household items such as a washing machine.
A list of websites which comply with the new rules will be available to consumers via the PAAG website.
Clarissa Baldwin, PAAG chair, said: "While we recognise that pets are commonly advertised online, it is still shocking to know that there are between 100,000 and 120,000 pet advertisements appearing on UK websites each day.
"The research undertaken by PAAG has revealed some truly terrible examples where animal welfare was clearly the last thought in the mind of the advertiser.
"Every day we hear from people who have bought an animal online only for it to fall sick or die soon after.
"We hope that the minimum standards will be just that, a minimum standard that a website must reach before posting advertisements for pets.
"In an ideal world we would prefer people not to buy pets online but would advise that if you are doing so that you check the website adheres to PAAG's minimum standards."