Abstract

The concept of trait impulsivity has been well studied in the human psychological field; it underlies a range of human psychiatric problems and has been linked to serotonergic and dopaminergic functioning (Puumala & Sirvio, 1998). In dogs, impulsivity is ill-defined, having mainly been studied in relation to aggression. However, if impulsivity is a general behavioural trait, it would be expected that impulsivity is expressed in a wider range of behaviours. This study describes the identification of a behavioural profile for impulsivity and the development and validation of a psychometric assessment tool to detect this in dogs.

Methods
Questionnaire Development:
A predictive questionnaire of impulsivity based on expert opinion was developed by the authors and subject to a principal components analysis in order to explore the face construct validity of the questionnaire. Three factors relating to impulsivity were identified and interpreted as relating to Behavioural Regulation, Aggression with Response to Novelty and Responsiveness.
Laboratory Behaviour:
23 dogs were trained to use operant devices for food reinforces. Their impulse control was assessed based on a previously validated choice task using the Delayed Reward Paradigm (Wolff & Leander, 2002)
Physiological markers:
Urine samples were collected from the subjects during their normal toileting routine. High Pressure Liquid Chromatography (HPLC) with Fluorometric Detection was used to detect levels of the metabolites of serotonin (5-HIAA) and dopamine (HVA) in the subjects’ urine.

Results
Higher questionnaire (impulsivity) scores significantly correlate with more impulsive behaviour in the laboratory behaviour tests (P<0.05) and lower levels of urinary 5-HIAA and 5-HIAA/HVA ratio (P<0.05).

Discussion
This study has developed a reliable and valid tool for assessing impulsivity in dogs. It has provided evidence that the trait impulsivity does exist in this species and that there is a relationship with serotonergic and dopaminergic functioning. These findings are consistent with those in the human and other non-human animal literature.