Effect of topical florfenicol, terbinafine and mometasone furoate ear drops on adrenocortical function in healthy small breed dogs with bilateral otitis externa.

Abstract

Testing for hyperadrenocorticism is commonly pursued in adult dogs with dermatological disease, and adrenocortical suppression has been well-documented following the use of topical corticosteroids in otic preparations. An otic suspension that contains florfenicol, terbinafine and mometasone furoate, and lasts for 30 days after a single application, frequently is used to treat canine otitis externa (OE). This medication was shown to cause adrenocortical suppression on Day (D)2 postadministration and two weeks after two applications two weeks apart. The objective of this study was to determine if topical florfenicol/terbinafine/mometasone furoate causes adrenocortical suppression in healthy, small-breed dogs with bilateral OE at D28 postapplication. Seven client-owned dogs weighing <10 kg diagnosed with non-Pseudomonas bilateral OE. Cortisol was measured pre- and post-adrenocorticotropic (ACTH) stimulation on D0. Topical florfenicol/terbinafine/mometasone furoate was applied in both ears. Dogs were reassessed on D28, and cortisol was measured pre- and post-ACTH stimulation. The median pre- and post-ACTH cortisol concentrations on D28 were 2.5 µg/dL (range 2.0-5.0 µg/dL) and 14.3 µg/dL (range 11.5-23.1 µg/dL), respectively. There was no significant difference (P = 0.85) between post-ACTH cortisol concentrations from D0 to D28. Results demonstrated no evidence of adrenocortical suppression, suggesting that there is no need to delay adrenocortical function testing in dogs treated with topical florfenicol/terbinafine/mometasone furoate when applied as per the manufacturer's recommendations.