How Resilient Are Dogs to Stressful Experiences?

The lifelong emotional status of the search-and-rescue dogs deployed on 9/11.

Posted Dec 04, 2020

 Andrea Booher, FEMA News Photo/Public Domain
Source: Andrea Booher, FEMA News Photo/Public Domain

In the aftermath of the 9/11 terrorist attacks on the World Trade Center stories began to appear in the media about stress-related problems suffered by people engaged in the sad task of searching for victims in the rubble. These stress-related problems did not only affect the people involved in the search and rescue operations on-site, but many residents of New York who lived nearby and were directly impacted by the attack. There were also media reports that some of the search and rescue dogs working on site were suffering from post-traumatic stress disorder (PTSD) as well.

PTSD is a mental health condition that is usually triggered by a terrifying event or a sustained series of such events. In people, the symptoms include flashbacks, nightmares, severe anxiety, and uncontrollable thoughts related to the event. When a person is in danger it's natural to feel afraid, and this fear triggers changes in the body to defend against or avoid danger. This is the so-called "fight or flight" response, which is a healthy reaction, but in PTSD this response has gone awry. People with PTSD may feel stressed or frightened even when they are no longer in danger, and the symptoms can get worse over months or even years. This can be seen in the case of these terrorist attacks since more than 21 percent of New York City residents enrolled in the World Trade Center Health Registry reported new PTSD symptoms five to six years after 9/11. Probable cases of PTSD among the residents increased from more than 13 percent two to three years after the attacks to more than 16 percent five to six years later.

This raises the question as to whether the dogs called upon to serve at the attack sites were also impacted by PTSD or other stress-related problems because of the work that they did at that time. The answer has now been provided by a team of researchers headed by Elizabeth Hare at the Penn Vet Working Dog Center in the School of Veterinary Medicine at the University of Pennsylvania in Philadelphia.

This was one of those studies which required major, sustained, efforts on the part of the investigators. It involved 150 search-and-rescue dogs. A total of 95 were actually deployed to work on-site, and 55 were also trained search-and-rescue dogs who were not used to work on this particular disaster. The terrorist attacks occurred in September of 2001 and the data collection began in October of 2001 and lasted for 15 years, until the final canine participant died. Questionnaires were filled out annually over the course of each dog's life.

The questionnaire used was the Canine Behavioral Assessment and Research Questionnaire (usually abbreviated as the C-BARQ) which was developed by James Serpell and his and his associates at the University of Pennsylvania. It is a long questionnaire, involving 101 items. It is one of the best known, and most carefully validated questionnaires that assess a dog's behavioral characteristics. The majority of the items cluster into subscales such as trainability, several types of fear and aggression, chasing, and attention-seeking. Most of these items describe behaviors considered to be problems (with the exception of most of the trainability items). The C-BARQ is usually completed by puppy raisers for service dog puppies, owners for pet dogs, and handlers for working dogs. It depends upon responses from the person who knows the dog best and provides a method for is directly reporting the occurrence or non-occurrence of specific behaviors in their dogs in a structured way.

Since these questionnaires were administered over the lifetime of these search and rescue dogs it is not surprising that some clear age-related changes were observed. In terms of trainability, these behaviors were stable for about four years post-deployment and then decreased steadily with age, confirming observations typically observed in aging dogs. The touch sensitivity of these dogs increased steadily with age, while their excitability and attention-seeking decreased steadily with age. As we also would expect, the energy level shown by the dogs decreased slowly for several years, and then decreased more steadily for the remainder of their lives.

But what about the emotional and behavioral effects on the dogs who were actually deployed to work on the sites impacted by the terrorist attacks? When a direct comparison was made between the dogs who were directly used in search and rescue efforts at the World Trade Center or the Pentagon, versus dogs with similar training who were not used for those tasks, the researchers found no differences whatsoever. They conclude simply that "9/11 deployment did not adversely affect behavior in search-and-rescue dogs."

For the people working with these highly trained dogs in what ultimately turned out to be a sad, frightening, and hopeless task, there are bound to the strong emotional responses. The humans involved recognize the impact of what is taking place and its significance. For the dogs, however, if they had been well trained, their actual deployment to search through the rubble for possible survivors should be no different in the canine mind than any of their many previous training exercises. They do not understand that what they find or do not find may represent the salvaging or the loss of the hopes and dreams of a particular individual or his or her family. Their ignorance is bliss and protects them from the stress that their human handlers may be experiencing and allows the researchers to conclude that "Dogs’ behavior appears to be resilient to stressful experiences."

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Hare E, Kelsey KM, Niedermeyer GM, Otto CM, (2020). Long-Term Behavioral Resilience in Search-and-Rescue Dogs Responding to the September 11, 2001 Terrorist Attacks, Applied Animal Behaviour Science, doi:

Brackbill RM, Hadler JL, Ekenga CC, et al. (2009). Asthma and Posttraumatic Stress Symptoms 5 to 6 Years Following Exposure to the WTC Terrorist Attack. Journal of the American Medical Association, 302(5), 502-516