More than 5 percent of military dogs serving in Iraq and Afghanistan are developing post-traumatic stress disorder (PTSD), according to the New York Times.

Dogs are often used in combat zones to sniff out bombs, clear buildings of people, or locate enemy fighters. A military dog famously participated in the raid that found and killed Osama bin Laden last May. About 650 military dogs currently serve in Iraq and Afghanistan, down from a high of 1,200. A total of 2,700 dogs are on active military duty.

While the use of dogs can help save human lives, life in a combat zone can have a high cost on the canines themselves. According to the Times, the symptoms of canine PTSD are very similar to those in humans suffering from trauma. Some dogs become hyper-vigilant, while others become either more aggressive or more timid. They might not be able to enter buildings or other areas where they once felt comfortable, and they might simply stop performing the tasks for which they were trained.

For dogs trained to locate explosives, this presents a danger not only to the animals but to their human handlers and the soldiers that rely upon them, according to Dr. Walter F. Burghardt Jr., chief of behavioral medicine at the Daniel E. Holland Military Working Dog Hospital at Lackland Air Force Base in San Antonio.

Dr. Burghardt has developed several videos, which the New York Times has posted with their article, to help veterinarians understand the symptoms of canine PTSD. He also consults with military veterinarians around the world via Skype or email.

The military has been cautioning about canine PTSD for some time. "Our biggest issue that we have with canines is canine PTSD," Army Lt. Col. Richard A. Vargus told Military Times in September. "We've seen a significant issue with that because when you're standing 10 feet away from an explosion, the dog has emotions and the dog is affected as well." Vargus said that a dog experiencing fear reactions could bite its handler, run away and hide, or simply cower when its team is preparing to go on patrol.

Treatment for dogs with PTSD is difficult since the animals can't communicate with therapists the way humans can. Sometimes extra exercise and obedience training can help. Others undergo "desensitization conditioning," which is similar to work done to alleviate phobias. Some are prescribed anti-anxiety medications such as Xanax. Many are retired from service or moved to non-combat operations.

Last year, CBS's "The Early Show" covered a case of one dog, a German shepherd named Gina, who suffered from PTSD after a six-month tour in Iraq and the successful efforts to rehabilitate her. You can see a video snippet from that show below:

Also on MNN: