Successful Treatment of Cutaneous Lupus Erythematosus in a Horse With Tacrolimus Ointment.

Overview

• This study reports the successful management of cutaneous lupus erythematosus (CLE) in a horse using topical tacrolimus ointment and a UV-blocking mask over a three-year period without adverse effects.

Introduction to Cutaneous Lupus Erythematosus in Horses

• Cutaneous lupus erythematosus (CLE) is an autoimmune skin disease that causes lesions and inflammation.
• It can be triggered or exacerbated by ultraviolet (UV) light exposure, leading to flares that worsen skin lesions.
• The disease is characterized by lesions on sun-exposed areas, with the eyelid being a common site in horses.

Subject and Diagnosis

• The subject of this report was a 9-year-old gelding Quarter Horse presenting with a lesion on the right upper eyelid.
• Clinical examination and likely supportive diagnostic techniques (e.g., biopsy, histopathology) were used to confirm the diagnosis of CLE.

Treatment Approach

• Topical application of tacrolimus ointment was used as the primary treatment.
• Tacrolimus is an immunomodulating agent that inhibits T-cell activation, thereby reducing autoimmune inflammation.
• Alongside tacrolimus, a UV-blocking mask was employed to prevent UV-induced disease flares, protecting the sensitive skin areas from sunlight.

Results and Efficacy

• Clinical resolution of the eyelid lesion was achieved with this combined treatment approach.
• The horse was able to maintain disease control for 3 years, with management of flare-ups linked to UV exposure.
• No adverse effects were observed during this extended treatment period, indicating good safety and tolerability of topical tacrolimus in this context.

Significance and Implications

• This case demonstrates that tacrolimus ointment can be an effective and safe option for treating CLE in horses, a condition that can be difficult to manage.
• Using a UV-blocking mask as adjunctive therapy helped prevent flare-ups and likely contributed to sustained disease remission.
• The findings suggest potential for tacrolimus to be considered in equine dermatological autoimmune treatments where immunosuppressive therapies are needed but systemic side effects are undesirable.
• Long-term follow-up supports the feasibility of chronic management with topical agents in conjunction with environmental modifications.