Tacrolimus therapy for dermal arteritis of the nasal philtrum refractory to surgery and anti‐inflammatory therapy (doxycycline/niacinamide and topical fluocinolone) in a dog

Background Dermal arteritis of the nasal philtrum is a rarely reported condition commonly affecting large breed dogs. Objective To describe the effective treatment of nasal philtrum arteritis with topical tacrolimus in one dog. Animal A 9‐year‐old, intact male German shorthair pointer dog was presented with well‐demarcated deep erythematous ulcers targeting exclusively the skin of the nasal philtrum, accompanied by frequent series of haemorrhage. Methods Complete blood count, serum chemistry profile, urinalysis, histopathological examination and immunohistochemistry of skin biopsies. Results The presence of a V‐shaped ulcer with subendothelial spindle cell proliferation resulting in stenosis of dermal arteries and arterioles on histological evaluation, together with a well‐demarcated deep nasal philtrum ulcer was consistent with arteritis of the nasal philtrum. Treatment was initiated with twice daily oral doxycycline and niacinamide in conjunction with topical fluocinolone cream. Over the course of two years, the lesions progressed with frequent bleeding episodes. A novel surgical approach provided deep resection of all grossly affected tissue; four months later a recurrence of fissures and occasional mild bleeding from the original site was noted and there was no improvement after another two months of oral doxycycline/niacinamide and topical fluocinolone treatment. Topical application of 0.1% tacrolimus twice daily resulted in complete healing of the ulceration and normalization of the epidermis. Over the subsequent 15 months, the dog's lesions remained in remission with topical tacrolimus application twice daily. Conclusions and clinical importance Topical tacrolimus ointment appeared effective at inducing and maintaining lesion remission in this dog with nasal philtrum arteritis.