A double-blind comparison of olive oil and a combination of evening primrose oil and fish oil in the management of canine atopy.

A randomised double-blind parallel study lasting eight weeks was used to assess the effects of olive oil in a group of atopic dogs whose clinical signs were well controlled by dietary supplementation with a combination of evening primrose oil and fish oil. Nine of the 11 dogs which continued to receive this combination were considered unchanged at the conclusion of the study, whereas eight of the 10 dogs switched to olive oil had deteriorated. The mean plasma concentration of dihomogammalinolenic acid, a precursor of potentially antiinflammatory mediators, was significantly reduced (P < 0.05) in the olive oil-treated group at the end of the study. There were no significant differences between the mean plasma linoleic, eicosapentaenoic and arachidonic acid concentrations in the two groups. These findings suggest that olive oil is not an effective therapeutic agent in the control of canine atopy.