After four months of arduous training, three K-9s graduated from the CIA fall 2017 "puppy class" this week.

Nicole, Indigo and Freya passed the two required certification tests from the Bureau of Alcohol, Tobacco and Firearms (ATF) and the United States Police Canine Association (USPCA) that ensure the dogs can detect explosives.

Dogs Freya, Indigo, and Heide graduated from the CIA Fall 2017 "Puppy Class", Dec. 8, 2017.

Freya and her handler were awarded the class's top dog award for earning 298.68 out of a possible 300 points — the highest score on the USPCA test.

Dog Freya plays with gifts during the CIA Fall 2017 "Puppy Class" graduation.

Two other K-9s, Heide and Harry, also passed the certifications and will work for Virginia's Frederick County fire marshal and the Fairfax County Police Department, respectively.

Harry joined this season's puppy class five weeks late after another dog, Lulu, dropped out of the program.

Lulu "began to show signs that she wasn't interested in detecting explosive odors," the CIA said in a press release in October.

While sometimes dogs can act uninterested in odor detection temporarily, the CIA determined Lulu's indifference was permanent.

"Even when they could motivate her with food and play to search, she was clearly not enjoying herself any longer," the CIA said. "Our trainers' top concern is the physical and mental well-being of our dogs, so they made the extremely difficult decision to do what's best for Lulu and drop her from the program."

Luckily, Lulu was adopted by her handler and now "enjoys her days playing with his kids, sniffing out rabbits and squirrels in the backyard and eating meals and snacks out of a dog dish," the CIA said.

One other K-9 — Suni, described by the CIA as a "smart, silly, sassy Labrador" — did not graduate for reasons out of the dog's control.

Suni's prospective handler could not attend the second part of the training, so she was adopted by the family that raised her until she was 18 months old.

Dog Suni runs through the grass during the CIA Fall 2017 "Puppy Class" initial evaluations.

Honoring K-9s leaving service

The three CIA handlers who got new dogs this week had to say goodbye to the K-9s they've worked with over the past seven to eight years. New dogs typically enter service at about 18 months of age, and the CIA retires each dog by the age of 9 years.

At graduation, the dogs are honored with a CIA plaque and a shadowbox containing photos, their badge and other items.

"The retired dogs sat quietly, heads held high, a wise calm much different than the boisterous puppy antics displayed by the younger, soon-to-be K-9 graduates," the CIA said. "The crowd, made up of family, friends and colleagues — all those who made the K-9 program possible — cheered for the veteran dogs as they were honored for their service."

The CIA describes the ceremony as "bittersweet" for the handlers.

"After working with them seven days a week for eight years, it's pretty hard to separate a team," the CIA said. "Just about all of our dogs retire with their handlers and their families. If a handler cannot adopt their retiring dog due to a family situation or other reasons, then the option is given to another handler in the K-9 unit. Since CIA's K-9 officers love these animals so much, you will hardly ever hear of a dog retiring outside of the unit."

Each of the dogs that retired this week was adopted by the handler.

CIA K-9s Osmond, Lucy, and Gears wait for the retirement portion of the ceremony, Dec. 8, 2017.

The three retiring K-9s — Gears, Lucy and Osmond — "dedicated their lives to serving and protecting this country," the CIA said.

Gears worked overseas for 750 days during his career and has swam in 30 states.

Lucy started her career as an ambassador dog for Puppies Behind Bars before joining the CIA.

Osmond won numerous K-9 explosive detection awards over the years.

Dog Osmond retired from service in the CIA during the Fall 2017 "Puppy Class" graduation.

Because Gears, Lucy and Osmond have left service, their veterinary care is no longer covered by the government. A nonprofit group, Paws of Honor, will provide medical care and routine physicals.

For more information about the fall 2017 puppy class, click here.