A comparative study of subcutaneous, intralymphatic and sublingual immunotherapy for the long‐term control of dogs with nonseasonal atopic dermatitis

Background: Allergen-specific immunotherapy (ASIT) is the only causative treatment of canine atopic dermatitis (cAD). Different routes for administration of ASIT have been used; however, comparative studies are lacking. Hypothesis/objectives: The present study compared the efficacy and safety of subcutaneous (SCIT), intralymphatic (ILIT) and sublingual (SLIT) immunotherapy. Animals: 30 atopic dogs were included and allocation to three groups (SCIT, n = 8; ILIT, n = 12; SLIT, n = 10) was determined by the owners. Methods and materials: ASIT was administered using routine protocols. The pruritus Visual Analog Scale (PVAS), canine atopic dermatitis extent and severity index (CADESI), concurrent medications and adverse events were recorded initially and one, three, six and 12 months later. The main outcome measure was return to a normal status, which included CADESI <12, PVAS <2.5 and medication score <10. Results: Drop-outs were distributed evenly and 23 dogs finished the study (SCIT, n = 6; ILIT, n = 10; SLIT, n = 7). Adverse reactions to treatment were rare. At the start of the study, the three groups were homogeneous with respect to clinical signs and concurrent medications. After 12 months of ASIT, the CADESI and PVAS had decreased with a stable medication score in the ILIT and SCIT groups (P < 0.05), while all three scores had increased in the SLIT group. Return to normal state was achieved in one of six (17%) dogs receiving SCIT, in six of 10 (60%) dogs receiving ILIT and in one of seven (14%) dogs receiving SLIT. Conclusions and clinical importance: These findings suggest that SCIT and ILIT improved clinical signs of cAD, whereas ILIT had a much higher return to normal rate