TRENTON, Maine — Between their diminutive size, playfulness and tendency to relieve themselves wherever they happen to be standing, the four puppies romping around Hancock County’s SPCA on Tuesday seemed no different from many other pups found at a Maine shelter.

But Joker, Jazz, Wendy and Mikey are unique in one key respect: the distance between their original home and their future adopted homes in Maine.

Just 36 hours earlier, the four “boonie dogs” were living in a shelter roughly 8,000 miles away on Guam, a Pacific island and U.S. territory closer to Japan than Hawaii.

The four puppies arrived by commercial airplane late Monday, the first of 12 bound from Guam to Maine this week as part of a program that is literally pushing the boundaries of what is already a thriving “dog rescue” industry in this state.

“The island of Guam has a huge dog overpopulation problem,” Tracy Shaw, executive director of the Hancock County SPCA, said Monday as the four wiry, short-haired pups lounged in their oversized kennels. “So we have jumped in to help them with the overpopulation problem.”

Every year, hundreds of dogs are “rescued” from overcrowded shelters in other states and brought to Maine for adoption. More than 50 organizations are licensed by the Maine Department of Agriculture to import dogs, the vast majority of which come from southern states with less aggressive spay/neutering programs and where unadopted pets face euthanasia.

But Guam? After all, the only county in the continental U.S. that juts farther east into the Atlantic than Hancock is its neighbor, Washington County. And some dogs in Maine shelters will ultimately be euthanized because they could not find homes.

Those are questions that Shaw evidently expected to field as word of the Guam puppies spread. Guam’s dog overpopulation problem is so severe, she explained, that the island’s single shelter has already euthanized more than 400 dogs so far this year.

Shaw added that the Trenton shelter is open to other arrangements and already works with other animal rescue organizations that import dogs from southern states.

“This just happens to be a [shelter] that we know was receiving no assistance at all and so many of the shelters in southern states are receiving resources,” she said.

“We are very happy that we can save their lives,” she added.

In addition to importing dogs to Maine, the Hancock SPCA is helping establish and finance a spaying/neutering program in the Guam shelter aimed at reducing the overpopulation. A portion of the $500 adoption fee — which is double the traditional fee — will go toward the spay/neuter program after travel and medical care costs are covered. The shelter already has received six adoption applications for the dogs.

Dog adoptions from far-flung places are not uncommon in Maine. Many dogs are imported from so-called “kill shelters” in Alabama, Georgia and Mississippi. And earlier this year, a Knox County shelter brought in a few dozen chihuahuas from California.

But Maine state veterinarian Dr. Donald Hoenig said he was not aware of any other dog rescue programs between Maine and Guam.

Because Guam is a U.S. territory, any imported dogs would have to be given a thorough checkup by a veterinarian, receive a lengthy list of vaccinations and would be subject to a quarantine of between two and five days, depending on the dog’s age.

“It would be like any other interstate transport,” Hoenig said. Shaw added that the Hancock SPCA — a licensed dog importer — is well aware of the requirements and is following them, including imposing a seven-day quarantine.

The arrangement between the shelters in Guam and Trenton is a result of a message that Shaw received from a former supervisor of hers who is stationed with the U.S. Air Force in Guam. Major Kathy Jordan, the former commander of the 341st Military Working Dog program, reached out to Shaw to help after seeing the situation on the island.

So what does a “boonie dog” — as they are known in Guam — actually look like? All four of the 8- to 10-week-old pups in the shelter on Tuesday were small, short-haired and wiry, weighing just a few pounds each. Shaw said she expects them to grow to about 25 pounds.

But because they are likely mixed-breed dogs, boonie dogs may have big or floppy ears, straight or curly tails and come in a variety of shades. The smallest of the four, Jazz, resembled a dachshund while others had more terrier traits.

As for whether puppies from a Pacific island will transition well to life in cold and snowy Maine, Shaw said she saw no problems considering that the puppies likely lived on their own before ending up in the Guam shelter. She recommended they be treated as indoor pets. And after years of working with dogs — including hundreds of puppies — Shaw was impressed with the boonies.

“These have to be some of the best tempered puppies I’ve come across,” she said.

Anyone interested in adopting one of the Guam rescue dogs will have to go through the traditional application process for any adoption. Although adoptions will not begin until next week, the shelter is already taking applications.

The public will be able to see the boonie dog puppies beginning Friday after 11 a.m. at the Trenton shelter.

Donations to the shelter’s “Island Hopping Campaign” also can be mailed to SPCA of Hancock County, 141 Bar Harbor Road, Trenton 04605.

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