A pair of month old spaniels, thought to be linked to the illegal puppy trade, died after being abandoned in Lockerbie.
Both dogs were found by a member of the public in the town last Thursday. One died and the other had to be put down.
The Scottish SPCA suspects the two dogs came from a low-welfare puppy farm and passed through Cairnryan.
An undercover SSPCA inspector said: “In the past we have come across similar cases where any puppies who fall ill on the journey are simply discarded and left to die.
“These young dogs were only four weeks old and should have still been with their mother and littermates.
“Instead they were left to die alone and afraid at the side of the road. This is the true cost of the puppy trade.”
He added: “The supply for badly-bred puppies will only disappear if public demand stops.
“Every year thousands of pups are dying at just days or weeks old to fuel the trade.”
South Scotland MSP Emma Harper said: “This incident in Lockerbie is absolutely tragic and highlights the continuous cruelty of the illegal puppy trade which, during the Covid-19 pandemic and lockdown, saw a shocking increase in activity.
“During lockdown there has been a 46 per cent increase of dogs coming into Scotland and the UK from Romania, many through the port of Cairnryan.
“I have actively campaigned against this since my election in 2016. I continue to work with the Scottish SPCA and others on these issues.
“I’d remind everyone looking for a dog to visit the SSPCA assured breeders site and to always see it with its mum.”
Anyone with information about the puppy trade can contact the SSPCA on 03000 999 999.