More than five per cent of the 650 currently deployed by U.S. forces have PTSD, and of those about half are likely to be retired from service.
Although vets have long diagnosed behavioral problems in animals, the concept of canine PTSD is only about 18 months old, and is still the subject of debate.
Like humans with the disorder, different dogs show different symptoms. Some become hyper-vigilant. Others avoid buildings or work areas that they had previously been comfortable in.
It's a fact that fears once learned are never unlearned.
Treatment for canine PTSD can be very difficult because the patient cannot explain what is wrong, vets and handlers must make educated guesses about the traumatizing events.
Care can be as simple as taking a dog off patrol and giving it lots of exercise, playtime and gentle obedience training. Some dogs are also treated with the same medications used to fight panic attacks in humans.
Just as physicians have yet to find a surefire way to treat PTSD among humans, so too are veterinarians weighing a wide range of options when it comes to helping their canine patients. Some focus on exercise and gentle obedience training, others go the more aggressive route and prescribe medications and counter conditioning.
Dogs that do not recover quickly are returned to their home bases for longer-term treatment.
But if they continue to show symptoms after three months, they are usually retired or transferred to different duties.
Military Dog adoptions: