Trained with a tennis ball as a reward, Eros apparently got a tennis ball into his cage in Baltimore when no one noticed, popped it, chewed it and then swallowed it, Shantz said.
With no inkling of the looming health trouble, Shantz and Eros returned to Hagerstown and went back to work.
"I noticed that he'd get hungry and eat but then about 12 hours later, everything would come back up," Shantz said.
Over the next few weeks, the dog began losing weight, dropping 10 pounds before the ordeal was over, Shantz said.
She took Eros to the Park Circle Animal Hospital where Dr. Lindsay Kerfoot thought there might be a blockage but nothing showed up in the X-Rays.
Dr. Karen Rasmussen concurred with the blockage diagnosis and plans were made to perform surgery, Shantz said.
Eros was anesthetized and within minutes, the surgeon, Dr. Lemuel Halterman was able to confirm everyone's suspicions.
"They found about half of a tennis ball, still in one piece, lodged in the colon," Shantz said. "Dr. Halterman said he didn't think something that large could have gotten that far but it did."
Shantz said the ball had apparently been lodged in the colon for about a month. "It was really gross," Shantz said.
The ball was removed, unblocking the colon, Shantz said. Since the surgery, Eros has been steadily improving and regaining weight.
Eros is an official member of the police department and as such, all his medical expenses - $500 - are paid by the department, Shantz said.
Named after the Greek god of love, Eros came to Shantz when he was 2 years old for a cost of $4,700. He is cross-trained in English and German, Shantz said.
"The department bought Eros already trained in patrol and drugs," Shantz said. "We hit the streets as a team in just three weeks."
When a dog is bought untrained, the human partner has to train extensively with the dog, sometimes for months - a much more expensive proposition for the police department, Shantz said.