Comparison of serum brain-derived neurotrophic factor in dogs with and without separation anxiety

Abstract

Separation anxiety is a common behavior disorder, but our understanding of its etiology and underlying neurochemical mechanisms remains limited. The purpose of this study was to compare serum brain-derived neurotrophic factor (BDNF) levels in dogs with and without separation anxiety. BDNF, one of several neurotrophins, is prevalent in the limbic region and prefrontal cortex, which are key areas related to the regulation of mood, emotion, and cognition. Although an enriched environment increases BDNF levels, stress and glucocorticoid exposure decrease the expression of BDNF in the hippocampus and prefrontal cortex. As separation anxiety is associated with chronic stress, we hypothesized that BDNF levels in dogs affected by separation anxiety would be lower than BDNF levels in nonaffected dogs. A total of forty-eight dogs were classified by a board-certified behaviorist as affected (n = 15) or nonaffected (n = 33) by separation anxiety based on review of video clips of the dogs when left alone and owner reports of the dogs’ behavior. Groups did not differ in regard to age, body weight, body condition score, or sex, and most dogs were mixed breed. Fasted serum samples were analyzed with a canine BDNF ELISA. Nine (60%) dogs in the affected group and 12 (36%) dogs in the nonaffected group had a BDNF level <0.156 ng/ml, the minimally detectable level of the ELISA. The median (range) serum BDNF level was 0.10 (0.02-1.05) ng/ml for the affected group and 0.40 (0.03-9.98) ng/ml for the nonaffected group, after replacing the undetectable values with a random value between 0 and 0.156. The difference in BDNF level between the groups was significant (P = 0.037). The finding suggests the potential of serum BDNF as a biomarker for anxiety-related disorders in dogs.