Rogue puppy dealers are using Facebook and Instagram to trade across Europe, often selling animals with fashionable mutilations such as cropped ears, an investigation has found.

Analysis of hundreds of posts found that trade is rife in underage pets and dogs bred with exaggerated features including excessive skin folds, which cause dermatitis, and very short muzzles, which leave animals struggling to breathe.

The craze for such puppies has allowed breeders to cash in using social media, where pets are easily advertised despite rules curbing the sale of live animals.

Sellers easily evade the social media giants’ guidelines by using code words, and emojis and hashtags with secret meanings, according to a report by the Four Paws global animal-welfare organisation.

Meta, which owns Facebook and Instagram, says it removes adverts that breach its rules as soon as it becomes aware of them. But the report says the platforms are hot spots for cruel and unethical puppy sellers.

Underage puppies for sale are often bred in poor conditions and transported illegally across borders from eastern Europe, according to the investigators.