DENVER -- A popular pet treat promotes fresh breath and clean teeth for dogs and cats. But several local pet owners have had problems with their pets not being able to digest the Greenies or even choke on the treats.

Laurie Gaynor said one of her dogs choked on a Greenie after trying the treat for the first time. She said the dog even vomited pieces of the treat hours later.

Gaynor said since the package claims the treats are 100 percent edible, she didn't expect that it could harm her dog.

"It really frightened me that somebody could choke that easily on them," said Gaynor. "These things can cost upwards of $20 a bag and they say on the front of them that they're highly digestible."

Veterinarians at Parker's Animal Emergency and Specialty Center have also had several problems with Greenies.

"We've had cases where the Greenies have been in the stomach and we've had cases where the Greenies are lodged in the esophagus -- the tube leading down to the stomach," said veterinarian Dr. Adam Rosenberg.

One recent case ended tragically.

"He was in the hospital for four days, almost five days, and had two separate surgeries to try to bring him through it and, ultimately, we were unsuccessful and he didn't make it," said Rosenberg.

On each package of Greenies, there is a caution label that says to monitor your dog to make sure the treat is properly chewed. It does say that gulping any item can be harmful or even fatal to the dog.

"To this day she has esophagus spasms and chokes almost every day because she feels like there's still something stuck in her throat," said Gaynor, of her pet.

She contacted the company, who told her that maybe the pieces were too big for her dog. They even sent her smaller versions of the treats.

The manufacturers of Greenies said, "We were extremely sad to hear about this dog, and hope he or she is recovering well. Millions of Greenies are sold every week. Very rarely we hear about a dog having a problem with Greenies. We thoroughly investigate the incident, and typically find out that the dog had an allergic reaction to our product, received the incorrect size for his or her weight and age as emphasized on our packaging, or swallowed an abnormally large piece without chewing it. Because we are uncertain of the details of this incident, we can't comment on it specifically. We wish the very best for this pet and pet owner."

If you have a question or concern about Greenies, the manufacturer would like to hear from you. Contact them at info@Greenies.com.