Staff at Derby's Cats Protection Adoption Centre are warning people not to impulsively buy cats online as they say people cannot properly check their health.
The organisation says they have seen cats brought into them that have been bought online and have had to be given up.
Jake, pictured above, was one of those cats and had to be relinquished after his owner struggled to pay for a complex medical condition.
Staff at the site in Derby are urging people to do thorough research before buying their pet to avoid any issues.
Helen Wood, manager of the Cats Protection Adoption Centre in Derby, said: "Jake was brought into our care, he was an owned cat and the owners had done their best for him and he'd had some treatment for an illness.
"Unfortunately because of the costs they weren't able to continue with the treatment so when he came into our care he'd got hyperthyroidism and was quite poorly.
"But he was able to have an operation, he's made a really good recovery and hopefully now he'll soon find a new home."
Ms Wood said they had seen cats come in that had been bought online.
She said: "We are starting to se cats, people have bought them perhaps without thinking about it in advance and they need to relinquish the cats and they are asking us to help to take them in."
Ms Wood also gave some advice to people about buying cats.
She said: "Give it a lot of thought, make sure you are going to somebody that's reputable make sure you consider the costs of having a cat.
"If it's a kitten there's neutering, vaccinating, microchipping, flea-ing and worming. Even an adult cat may need all that doing and there's also costs in their future.
"There may be vet bills so it's just really researching it before you just see a pretty picture of a cat and just go ahead it.
"There needs to be a lot of thought, you could have the cat for up to 20 years or more."