High demand for pugs, dachshunds and French bulldogs is fuelling the "sickening trade", the Dogs Trust warns.
The warning comes after almost 100 puppies were seized in just a week during a covert operation at the United Kingdom border control as devious importers hone in on the Christmas trade.
Hundreds of puppies are being smuggled into the United Kingdom to cope with the demand in the run up to Christmas, authorities have warned.
Dogs Trust are giving advice on how to avoid purchasing puppies which are being smuggled into the country, with many animals experiencing "shocking" conditions as they enter the UK.
Demand for in-trend breeds such as French Bulldog, English Bulldog, Chow Chows and Daschund has seen a rise in the "sickening trade".
In 2016, some 275,876 dogs travelled to Britain, more than treble the recorded number in 2011.
Dogs Trust veterinary director Paula Boyden said: "Buying an illegally imported puppy could potentially cost well-meaning but unsuspecting families thousands of pounds in quarantine and vet bills and emotional heartache for the family if the puppy falls ill or worse, dies". Seven cane corso pups reportedly had their ears and tails illegally cropped and docked with scissors and vodka.
Ask to see the mother and pup together, visit the new pup a few times and get paperwork before taking it home.
Report suspicious sellers and take new puppies to their own vet for a health check as soon as possible.
The trust also advises people not to meet anywhere that is not the puppy's home, buy from anyone who can supply various breeds on demand, buy a puppy that looks too young/small or underweight, or allow yourself to be pressured into a sale. Miss Boyden added: 'We continue to be astounded at the lengths these deceptive breeders and dealers will go'.
Only half (48%) of respondents the Dogs Trust surveyed said they would be concerned if their most recently bought puppy was imported illegally and a third (33%) said they would buy a dog from an online classified site or social media - highlighting the scale of the problem.
A spokesperson for the Department for Environment, Food and Rural Affairs said: "We are cracking down on animal trafficking with one of the toughest pet border checking regimes in the world".