Border control officers stopped the van in the city of Mulhouse, France.
The van, which had Slovakian licence plates, was delivering the puppies to a Spanish pet shop, where they'll be sold off for a huge profit.
A shocking discovery
The pups were hungry, dehydrated, and displaying signs of stress and anxiety.
Welfare officers from the Society for the Protection of Animals (SPA) took charge of the pups. However, they were forced to hand them back to the driver due to a legal technicality.
He then continued on his journey with all 100 pups in the back of his van. Officers from the SPA believe that some of the puppies won't make it to Spain alive.
The SPA shared the story on social media, along with a petition demanding changes to European animal welfare laws.
Puppies need more protection
"This carrier alone transfers a hundred puppies from Slovakia to a pet store in Spain every two weeks; this is real trafficking in appalling conditions with appalling mortality," read one SPA post.
More than 60,000 people signed the petition within the first week. Now it's time for the authorities to sit up, take notice, and do the right thing. Puppy trafficking has to end.