Like most puppies, Zoey is energetic and insatiably curious. When she’s outside, the 3-month-old yellow Labrador keeps her nose pointed to the ground, sniffing things, tackling flowers and chewing on random objects without hesitation.

Such was the case on a recent morning, when owner Peter Thibault took Zoey out for a walk on their wooded neighborhood street in Andover, Massachusetts. At some point, he noticed Zoey had lunged toward an empty cigarette box that had been discarded near a tree – and then put it in her mouth. He bent down to try to take the package away from her.

“I was concerned about the tinfoil,” Thibault told The Washington Post. “She’s ingested a lot of strange stuff since we’ve had her … Labs are notorious for eating stuff.”

Less than a minute after he had wrested the cigarette box out of her mouth, Zoey fell over.

“It couldn’t have been in her mouth for longer than 30 seconds at the very most,” Thibault said. “She just collapsed on her side. She couldn’t stand up.”

At first, he assumed the dog had eaten something the night before that she was now having trouble passing. When Zoey didn’t respond to his nudging, he picked her up and carried her back home, a short distance away.

Thibault called his wife at work using FaceTime. Soon, Zoey’s eyes began rolling toward the back of her head; her tongue was hanging out, and she was laboring to breathe. It became clear that these were not just digestive issues.

“It was really my wife who urged me to call the vet hospital,” he said. “(Zoey) was getting progressively worse.”

Thibault loaded Zoey into the back seat of his car and whisked her to a nearby animal hospital that was open early. When he arrived, the doctor asked him to go over what had happened in the morning.

“She kept bringing me back to the cigarette box, (asking) ‘Was there anything in it?’ ” Thibault said. “Then they asked me to step out of the room.”

No more than five minutes later, they called him back in. To his shock, Zoey was upright and alert, as if nothing had happened.

The veterinarian told Thibault they had given Zoey a dose of naloxone, the generic form of Narcan, a medication used to counter the effects of an opioid overdose.

“I had never heard of Narcan before,” Thibault said. “I was in complete disbelief. I couldn’t believe it.”

Krista Vernaleken, a veterinarian and medical director at Bulger Veterinary Hospital, told the Boston Globe a variety of clues had led them to suspect Zoey may have come into opioids.

“That a collapse happened in an otherwise healthy dog who was fine just five minutes before, and knowing the dog had chewed on something on the street, there was a limited number (of) things that could be,” Vernaleken told the newspaper.

Thibault said doctors told him Zoey would have probably died if she had been brought in even 20 minutes later. He is alarmed to think about what could have happened if a child had come across the cigarette box, which was resting near where the school bus picks up his children every morning, he said. It is unclear what Zoey ingested. Even trace amounts of some opioids, like fentanyl, can be fatal to humans.

Vernaleken told the Boston Globe she has treated three similar cases of opioid overdoses in pets this year, and that no communities are off limits.