2.1. Animals

On the basis of inclusion criteria, out of more than 108 dogs referred to the Veterinary Teaching Hospital of the University of Turin for episodes of aggression towards owners for at least 2 months and not more than 4, 8 dogs were included in the study. The group (7 males and 1 females) consisted of dogs of different breeds: German Shepherd (1), Cocker Spaniel (1), Jack Russell (1), Boxer (1), and mixed breed (4). The mean age was 3.6 years (ranging from 1.2 to 6 years). The dogs showed no clinical signs but aggression and had received no pharmacological treatment. At the time of enrollment, the presence of any concurrent medical condition contributing to aggression was excluded by means of physical and neurological examination carried out by a board-certified neurologist and by serum biochemistry, complete blood count, and thyroid hormone levels (TSH andtotal thyroxine). Among inclusion criteria, there was the possibility to manage dogs without using sedation.

The diagnosis of dominance-related aggression (owner-directed) was made by a behaviorist expert on the basis of anamnesis and clinical evaluation. The behavioral case history was collected by a questionnaire filled out directly by the owner, who was asked to describe a series of situations (e.g., food-related aggression; disturbed while resting; physical contact; postural or behavioral provocation by the victim) in which the dog displayed aggressive behavior [10]. Clinical diagnosis of aggression was established on a five-point frequency scale (0–4; higher score indicates more severe disease) for three different items concerning: (a) frequency of aggression episodes (F), (b) aggression intensity (I), (c) distance from the aggressive reaction to when the stimulus did not appear (D) (Table 1). The distance was defined according to the concept of the proxemic bubble, personal space surrounding the body that defines a sort of protective bubble: intimate (from 0 to about 0.5 m), personal (0.5 to 1.2 m), social (1.2 to 3 m), and public (greater than 3 m).

Evaluation of dog aggression on a five-point frequency scale (0–4).

A score ranging from 0 to 12 was assigned to each dog at the time of enrollment and at each further experimental time point. Dogs were considered for treatment if their clinical score was ≥8 at time of enrollment (T0).

During the follow-up, animals having a score ≤3 were considered to be fully responders to the therapy.