The Variation of Serotonin Values in Dogs in Different Environmental Conditions.

Serotonin is considered to be the neurotransmitter that controls several types of behavior: aggressiveness, impulsivity, food selection, stimulation, sexual behavior, reaction to pain, and emotional manifestations. The aim of this study was to determine the serotonin values in 43 dogs, divided into three different experimental variants: (1) between two groups of medium ( = 6) and small ( = 4) breed shelter dogs; (2) in dogs with ( = 15) and without ( = 10) owners after administration of pre-spaying/neutering anesthesia; (3) in different behavioral states ( = 8) classified as follows: M1-happy, M2-aggressive, M3-calmed status, post-exposure to a stressful situation, compared to the reference time referred to as M0. There were no significant differences ( ≥ 0.05) regarding the serotonin values between the two groups of medium and small breed shelter dogs. Following anesthesia, the average mean serotonin values were significantly lower ( ≤ 0.003), by 63.85 ng/mL, in stray dogs compared to dogs with owners. No significant differences ( ≥ 0.05) were found when comparing the reference time M0 to M1, M2, and M3. The differences decreased significantly ( ≤ 0.05), by 89.61 ng/mL, between M1 and M2 and increased significantly ( ≤ 0.008), by 112.78 ng/mL, between M2 and M3.