A randomised, double-blinded, controlled trial to determine the efficacy of combined therapy of oclacitinib and marine oil extract PCSO-524 in dogs with atopic dermatitis.

Background: Polyunsaturated fatty acids (PUFA) can be beneficial in the management of canine atopic dermatitis (cAD). A commercial product PCSO-524 containing PUFA has demonstrated anti-inflammatory effects in dogs.

Objective: To evaluate the efficacy of PCSO-524, in combination with oclacitinib in dogs with cAD.

Methods: Seventeen client-owned dogs with cAD. Methods: A randomised, double-blinded, controlled trial. All dogs were treated with oclacitinib (0.4-0.6 mg/kg) twice a day for 14 days, then once a day until Day (D)42. They were randomly divided into two groups: PCSO-524 (n = 9) and sunflower oil (n = 8). Clinical status was assessed by Canine Atopic Dermatitis Extent and Severity Index, 4th iteration (CADESI-04) and pruritus Visual Analog Scale (pVAS) at baseline (D0), D14, D28 and D42. Trans epidermal water loss (TEWL) was measured at the same time points.

Results: CADESI scores decreased significantly after treatment and there was a significant difference between the PCSO-524 and the control group at D28 (p = 0.04) and D42 (p = 0.03). The PCSO-524 group also demonstrated a significantly decreased pVAS on D28 and D42 (p < 0.001 and p < 0.001) compared to D0, while significant differences were observed in the control group at D14 and D28 (p < 0.01 and p = 0.04) and not at D42 (p = 0.12). The mean TEWL showed a significant decrease at D28 and D42 in the PCSO-524 group, compared to the control group (p = 0.002 and p < 0.001).

Conclusions: The combination of PCSO-524 and oclacitinib may help to alleviate the rebound effect that occurs when tapering down the dosage of oclacitinib, as compared to using oclacitinib alone for the management of cAD.