Steiss, J.E., Schaffer, C., Ahmad, H.A., & Voith, V. L. (2007). Evaluation of plasma cortisol levels and behavior in dogs wearing bark control collars. Applied Animal Behaviour Science, 106, 96-106.
On Week -1, 24 healthy mixed breed kennel dogs were screened by physical examination, complete blood
count, serum biochemistry, and plasma cortisol measurement. Dogs were tested to ensure they barked at an
unfamiliar dog. Dogs were randomly assigned to control, electronic bark collar or lemon spray bark collar
groups (n = 8 per group). On week 0 (acclimation baseline), dogs wore inactivated collars 30 min/day for 3
consecutive days. On weeks 1 and 2, dogs wore an activated collar 30 min/day for 3 consecutive days. Controls
wore an inactivated collar. The bark stimulus was an unfamiliar dog walked in front of the run, three times,
30 s per presentation. Plasma cortisol was measured week -1, week 0 day 3, week 1 day 1, week 1 day 3 and week 2 day 3. ACTH
was measured week 0 day 3 and week 1 day 1. Barking and activity were measured each session.
Results: Dogs wearing electronic or lemon spray collars barked less than controls (P < 0.05) by the 2nd day
wearing an activated collar, with no significant difference in barking between collars. Mean numbers of
collar corrections per dog on the 1st day wearing an activated collar were 4.0 (electronic) and 2.0 (lemon
spray); the values decreased to 0 for both collars on the 3rd day. ACTH levels did not differ among groups
(P > 0.05). Mean plasma cortisol levels were within the reference range for all groups throughout the study.
Overall, there was a significant time effect (P < 0.05) but no significant difference in plasma cortisol
between the control, lemon spray and electronic collar groups (P > 0.05). Activity did not change
significantly over time (P > 0.05).