The animal welfare charity seized 27 puppies on the morning of May 2 at Cairnryan port in Galloway.
The dogs, of various breeds, would likely have been sold for at least £600 each. All of the pups were taken back to Republic of Ireland where they are being cared for by the ISPCA while investigations are on-going.
The seizure was the result of a random stop by police at Cairnryan.
An SSPCA inspector said: “Unfortunately, the puppy trade is big business in Scotland with thousands of dogs being brought into the country each year from Northern Ireland and the Republic of Ireland, in particular from large scale puppy farms. They are then sold on at huge profit by the dealers.
“The illegal trade in puppies is still a major issue. The welfare of the breeding bitch and the puppies is compromised due to intensive breeding regimes and causes distress to the families who purchase these puppies.
“When trafficked pups reach their new owner via the dealers they often develop diseases such as parvo virus and giardia. Often the young dogs die from these diseases which can be extremely distressing for the owners.”
The charity has issued advice to anyone considering buying a puppy.
The inspector added: “Trafficked pups often look fine when they are purchased, but problems will begin to show at a later stage.
“We want to remind anyone looking to buy a puppy to please only go to reputable breeders, a list of registered breeders can be provided by the Kennel Club or your local council.”
“Always view the mother of any puppies that are for sale when the pups are still feeding from the mother, where possible it is best to view both parents. Never buy a puppy from a car park or allow for home delivery without visiting the breeder’s premises.
“If you have purchased a puppy that shows any signs of illness or distress take it to a vet immediately.”