Military dogs, especially improvised explosive device (IED)-detection dogs, work in war zones under harsh conditions. Being attuned to fear-inducing sounds and recovering quickly is a critical requirement. Margaret Gruen and her colleagues recently investigated a new method to assess sound induced fear and anxiety in candidate IED-detection dogs – specifically, Labrador retrievers.
An IED is a bomb constructed and deployed in ways other than in conventional military action. In the second Iraq War, IEDs were used extensively against US-led invasion forces. By the end of 2007 IEDs had become responsible for approximately 63% of coalition deaths in Iraq (source). In 2003, there were 81 recorded IED incidents in Afghanistan. In 2009, there were 7,228 (source: Washington Post). This emphasizes the need for reliable military dogs, dogs who are not easily affected by fear and anxiety due to loud sounds such as rapid gunfire, explosives and other military noise. Recently an Open Field Test using recorded thunderstorm sounds was shown to be a robust model of noise-induced fear and anxiety in laboratory beagles (Araujo et al., 2013). But is this test also a suitable indicator for emotional resilience in military dogs?
Attempts to induce fear and anxiety
For Gruen’s study, 16 Labradors were selected from a private training firm. The open field test (OFT) arena consisted of a room of approximately 3 x 3 m and included one hiding place to which the dogs could retreat. Two cameras monitored the dog at all times, when they were in the open as well as in hiding. Digital-audio recordings of thunderstorms or simulated gun battles were played for 3 minutes through two speakers at a fixed decibel level (104-105dB) during a 9-minute session in the OFT arena. The sound stimulus was only played on day 2 (thunderstorms) and day 4 (gunfire) of a five day test; on days 1, 3, and 5, only ambient noise was played.
Heart rate, cortisol (via saliva), and body temperature data were collected immediately before and after each 9-minute session. Behavioral data was collected during the entirety of the 9 minutes: EthoVision XT automatically tracked the distance travelled in the room, and the researchers used the dogs’ postures to calculate fear/anxiety scores.
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Indicators of habituation
Two forms of habituation were seen in the OFT. Over the course of five days, there was a significant decrease in distance traveled both within each day and across each subsequent day, suggesting that the dogs acclimated quickly to the room. Salivary cortisol, heart rate and body temperature levels did not decrease between sound stimulus test periods; however, heart rate did show an overall decrease within the control (stimulus free) sessions.
Persistence of sound-induced anxiety
What was interesting to see in the fear/anxiety scores was that after the sound stimulus of three minutes, the dogs’ scores quickly returned to the baseline level (period before the sound stimulus). However, the scores did not fall below baseline levels during sessions in which the sound stimulus was presented as they did during control periods. The overall increase in fear/anxiety scores on sound stimulus days suggests a persistence of sound-induced anxiety.
OFT is useful for evaluating candidate IED dogs
During the periods in which the thunderstorm or gunfire sounds were played, there was a significantly increased level of fear/anxiety scores and significantly increase in motor activity levels, suggesting that the OFT is a useful model for evaluating acute sound-induced aversion or fear reactions in candidate IED-dogs. OFT fear/anxiety scores correlated with a screening test for emotional resilience (Sherman et al, 2014), therefore making the OFT a suitable evaluation method for candidate Labrador retrievers to be used as IED dogs.
Find out more
Read more in the complete study:
Gruen, M.E.; Case, B.C.; Foster, M.L.; Lazarowski, L.; Fish, R.E.; Landsberg, G.; DePuy, V.; Dorman, D.C.; Sherman, B.L. (2015) The Use of an Open Field Model to Assess Sound-Induced Fear and Anxiety Associated Behaviors in Labrador Retrievers, Journal of Veterinary Behavior, doi: 10.1016/j.jveb.2015.03.007.
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- Araujo, J.A.; deRivera, C.; Landsberg, G.M.; Adams, P.E.; Milgram, N.W. (2013). Development and validation of a novel laboratory model of sound-induced fear and anxiety in Beagle dogs. J. Vet. Behav. Clin. Appl. Res. 8, 204-212
- Sherman, B.L.; Gruen, M.E.; Case, B.C.; Foster, M.L.; Fish, R.E.; Lazarowski, L.; DePuy, V.; Dorman, DC. (2014). Development of an emotional reactivity test for behavioral evaluation of explosive-detecting military working dogs, J. Vet. Behav. in submission.