From the study: Like humans, dogs can suffer from ADHD-like behaviors. A study from Spain analyzed the levels of serum serotonin and dopamine in dogs with signs similar to the ones presented in human patients with ADHD. Study data suggests a strong relationship between serotonin and dopamine and ADHD-like behaviors.
Dogs clinically classified as ADHD-like showed lower serotonin and dopamine concentrations.
Further, serotonin and dopamine levels were also linked to aggression, hyperactivity and impulsivity. Decreased serotonin concentrations were also related to fear, attachment and touch sensitivity. No relationship was found between serotonin and dopamine serum concentrations and attention deficits.
Source: MDPI, animals, March 13, 2023. Link.