CHICAGO (CBS) – A drug-sniffing dog had a big day at O’Hare Airport Monday allowing Customs and Border Protection officers to intercept four shipments of opium in a matter of hours.

One shipment was marked dresses, another cloth, and two were invoiced as traditional medicines. Each time, Shadow, an 8-year-old Belgian Malinois, alerted the officers, and got his reward. It alerted officers to the second, third and fourth packages in less than 30 minutes’ time.

All four shipments came from Laos. Two were destined for Wisconsin and two for Minnesota.

Customs and Border Protection spokesman Brian Bell said it’s all in a day’s play for the dog, which has been sniffing out drugs and other contraband for four years.

“The training involves starting off very simply. This is what marijuana smells like. You smell marijuana, you get rewarded. This is what opium smells like. You smell opium, and you alert us, you get rewarded. And that’s what Shadow’s motivation is,” Bell said. “Shadow wants to be rewarded. He wants to play with his little toy. So he’s out there looking for a reason to get that toy.”

Bell values the seizures at $489,000.