Aki, a nine-year old Belgian Shepherd dog based at Frankfurt's international airport in Germany, sniffed out almost a quarter of million euros in cash from travellers in a few days.
Between the end of June and the start of July, Aki caught 12 passengers carrying a total of €247,280 ($290,540), according to the airport's customs office.
In one incident, the nosy mutt sniffed out almost €52,000 in the belt bag of a passenger.
Other cash was found in handbags, shoulder bags and inside jacket pockets.
“With her keen nose, Aki supports the custom officers… in the fight against tax evasion, money laundering and international terrorism,” said Isabell Gillmann, spokeswoman at the customs office in Frankfurt, Germany's business capital.
All 12 travellers could face fines.
In 2019, customs officials in Frankfurt caught passengers carrying a total of around €23.6 million in undeclared cash.
According to EU laws in place since 2007, if passengers enter or leave the EU with €10,000 or more in cash, they must declare it and its origins to Customs.
These regulations are in place to help investigators detect any illegal activity involving high volumes of cash, such as drug trafficking or money laundering.
German sniffer dogs may also be put to use in the battle against coronavirus.
Researchers from Hanover's University of Veterinary Medicine found in July that man's best friend could detect Covid-19 in human samples, suggesting that in future they could be deployed in transport centres or sporting events.