Use of activity monitors for assessment of pruritus in an acute model of canine atopic dermatitis.

BACKGROUND

We developed a canine model of acute atopic dermatitis to evaluate the potential of compounds to treat pruritus and skin lesions induced in Dermatophagoides farinae (Df)-sensitized dogs.

HYPOTHESIS/OBJECTIVES: The aim was to investigate the effectiveness of long-term recording activity monitors to assess pruritus induced by allergen challenges.

ANIMALS

Thirty-two Df-sensitized laboratory dogs.

METHODS

In two blinded crossover studies, 28 Df-sensitized dogs were challenged on 3 days with a Df slurry applied to clipped abdominal skin. Dogs were treated with a positive control (prednisolone 1 mg/kg once daily for 5 days, starting 1 day before challenge) or left untreated; all were fitted with activity monitors. To confirm pruritus, a parallel study with four dogs was conducted, filming the dogs before and during challenge and assessing the film for pruritic behaviour.

RESULTS

The activity of dogs treated with prednisolone was significantly lower between 00.00 and 03.00 h and between 03.00 and 06.00 h compared with untreated dogs (repeated-measures ANCOVA; P < 0.0001). To determine whether the recorded night-time activity corresponded to pruritic manifestations, we compared activity monitor and video recordings of four dogs for two periods (16.30-20.30 and 24.00-03.00 h) before and during a Df challenge. The correlation between night-time activity monitor activity and observed pruritic behaviour was highly significant (test of correlation coefficient versus zero: r = 0.57, P < 0.0001).

CONCLUSIONS AND CLINICAL IMPORTANCE

Determination of night-time activity with activity monitors after allergen challenge appears to be an objective and practical way to assess pruritus in this experimental model of canine atopic dermatitis.