The young animals are being transported hundreds of miles, many in cramped conditions without food or water, and sold with false paperwork or passed off as 'home grown' pets.
Almost 70 puppies have been smuggled into Staffordshire in the past 12 months compared to 'one or two' in each of the previous two years, risking an outbreak of rabies.
The pups have been taken weeks before they are legally old enough to be moved without their mothers, say Trading Standards bosses.
The criminal activity is only discovered when the animals are taken to a vet for treatment and discrepancies are found between the information on their 'passport' and what the vet can see before them.
Although all breeds are involved, the market is being driven by the demand for certain dogs, particularly Pugs, French Bulldogs, Pekingese, English Bulldogs, Maltese, Bolognese/Bichons and Chihuahuas.
In 90 per cent of cases, owners are not even aware they have been sold a puppy from overseas.
Staffordshire County Councillor Mark Winnington, cabinet member for economy, environment and transport, said: "The youngest age a dog can legally imported with all its vaccinations is 15 weeks.
"But these traffickers think the dog is already losing its puppy cuteness by that stage and will be harder to sell, so they forge passports or break the rules to get it into the market place sooner.
"These breeds can be picked up for a few Euros in Eastern Europe and sold here for hundreds or thousands of pounds so it's a lucrative business where no thought is given to the dog's welfare."
The problem is a national one, with a ten-fold increase in illegally landed animals identified over the past couple of years. The number of illegally imported dogs found in Staffordshire rose to 69 in 2013/14.
Councillor Winnington said: "There is no guarantee that an illegally imported dog will have had any of the necessary vaccinations, which leads to a lot of heartache for the new owner.
"On the one hand it may already have something like parvo-virus, which could be fatal, or on the other if we find a dog has been imported illegally the owner will have to pay for it to be quarantined and to make sure it has all its vaccinations."
He urged dog lovers to take great care in buying a new pet and contact the authorities if they have any doubts.
He said: "It's public demand that's making this smuggling worthwhile for the traffickers, so people should look for the warning signs, such as the pup being cheaper than the usual price for that breed, or not being able to see it with its mother and rest of the litter."