Judy, the English pointer heroine of my new book, "No Better Friend," suffered mightily as a prisoner of war (yes--a dog who was a POW) in the jungles of Sumatra during WWII. She was also sunk two different times by enemy fire, forced to swim for her life in the South China Sea, and faced a multitude of other dangerous, high-stress situations.  When the war was over, she returned to a peaceful civilization, expected to simply “behave” as though her wartime experiences never occurred.

Similar burdens are placed on our dogs, in particular those rescued from difficult conditions and backgrounds.

In the 1940s, few humans, much less dogs, were diagnosed with what we would today call post-traumatic stress disorder (PTSD). But anecdotal evidence suggests Judy may have suffered from it, at least to some degree. Far harder proof exists that modern dogs can and do suffer from the disabling syndrome--and not just dogs that have been exposed to combat, as Judy was.

While the New York Times reported in 2011 that “more than five percent of the approximately 650 deployed military dogs are developing some form of canine PTSD,” that number is probably higher today. According to the Department of Defense, roughly 15% of the 1,700 working dogs used by the military are euthanized for extreme aggression or medical issues. How many of those animals are unfit for adoption or further service because of experienced trauma?

Meanwhile, a far larger and unknowable number of household dogs are potential casualties. Any kind of trauma, from fighting with other dogs to mistreatment at the hands of owners, current or previous, can trigger the canine version of PTSD.

Many people rid themselves of their pet dogs because of extreme behavior that they cannot comprehend or properly diagnose. The end result of this is often the putting down of the animal. This is particularly with rescue dogs, who naturally have a higher likeliness of background trauma (often inflicted upon them by humans). Such needless euthanizing can be avoided if, as with human sufferers, the symptoms are identified and not simply dismissed as the actions of a “bad dog.”

Sudden, aggressive changes in behavior and demeanor. Extensive skittishness. “Being bad around kids/people/other dogs.” Unexplainable whining, barking, or howling. These are just some of the indicators of potential PTSD in your dog. While “memory” as a concept of time doesn’t seem to exist in canines, they certainly are capable of emotional memory, and given their powerful senses of smell and hearing, the inciting factor may be not at all obvious to their human friends.

So what to do if you think your dog may have some form of trauma? The science is still new, but recent studies, in particular work done by animal scientist and psychologist Jaak Panksepp at Washington State University, have shown that rough, active play for even brief periods every day can help. The action apparently releases large amounts of brain-derived neurotrophic factors (BDNFs), which are associated with new neuronal growth--replacing the part of the brain that houses bad memories with new growth, and hence, new memories.

Not all dogs respond to this sort of non-traditional treatment. For them, herb and food therapies have been shown to help, as have appeasing pheromone supplements (often prescribed for separation anxiety), which lower stress. If these lower-impact methods aren’t enough, familiar anti-depressants like Prozac have been shown to work on dogs as well as humans. One thing you shouldn’t do is ignore the warning signs, or express frustration by dispensing further distress.

Judy’s life improved mightily when she left quiet and staid postwar England for a new life in Africa, one that featured regular rowdy interaction with people and other wildlife. You don’t need a passport or a troop of playful baboons to help improve your dog’s temperament. If your dog isn’t the same happy, friendly animal you know and cherish, seek out some professional advice.

It is ironic that at a time when we are belatedly discovering the great affect dogs can have as emotional support animals for human victims of PTSD, they may be suffering in silence themselves.

Robert Weintraub is a sports columnist for Slate, and his writing has also aired on ESPN, ABC Sports, CBS Sports, and dozens of other outlets. He is the author of "No Better Friend: One Man, One Dog, and Their Extraordinary Story of Courage and Survival in WWII" (Little, Brown and Company, May 5, 2015). He is also the author of "The House That Ruth Built" and "The Victory Season."