FC‐50 Results of repeat intradermal testing in 135 dogs

The usefulness of repeat intradermal testing (IDT) was assessed in 135 dogs in which initial IDT results were inconsistent with the history or when response to treatment was unsatisfactory. The interval between repeat IDT ranged from 8 days to 7 years. Repeat IDT was pursued: when a seasonal history was inconsistent with initial IDT results (45); response to immunotherapy (18) or flea treatment (3) was unsatisfactory; an elimination diet was unsuccessful (66); or for miscellaneous reasons (3). Fifteen dogs that had no reaction on first or second IDT were diagnosed with cutaneous food reaction (9), idiopathic seborrheic dermatitis (2), scabies (1), hypothyroidism (1), or an unidentified seasonal pruritus (1). The signs of the final dog in this group resolved with long‐term antibiotic therapy. Twenty‐two dogs that had negative initial IDT results developed one or more positive reactions on the repeat IDT and of these, 14 were started on immunotherapy. Forty‐four dogs with initial positive IDT results developed at least one additional significant reaction on repeat IDT leading to initiation or reformulation of immunotherapy in 34 dogs. Thirty‐three dogs with initial positive IDT results had the same number of reactions on repeat IDT, but reactions were not identical and prompted reformulation of immunotherapy. Twenty‐one dogs with initial positive results had fewer reactions on repeat IDT. In conclusion, these results provide evidence that repeat IDT is worthy of consideration in dogs with atopic dermatitis when initial IDT is negative, a seasonal history is inconsistent, or response to treatment has been suboptimal. Funding: Self‐funded.