Equine sarcoidosis: clinical signs, diagnosis, treatment and outcome of 22 cases

Abstract

Background – Equine sarcoidosis may present as a generalized or localized exfoliative dermatitis and/or as a granulomatous inflammation of multiple organs. Objectives – To report the clinical signs, diagnosis, treatment and outcome for 22 horses with histologically confirmed sarcoidosis. Animals – Twenty-two horses of different breeds, between 3 and 17 years of age. Methods – Diagnosis was based on clinical signs and histopathological findings. Results – The following three forms of equine sarcoidosis were identified: generalized (13.6%), partially generalized (18.2%) and localized (68.2%). High-dose systemic corticosteroids were used as the initial treatment in all three forms, followed by lower doses for a variable number of weeks. No local treatment was prescribed. Case outcome was variable; one of three cases of generalized sarcoidosis was euthanized immediately and the remaining two were euthanized after 2–3 months of unsuccessful treatment; all four cases of partially generalized sarcoidosis deteriorated despite treatment and were euthanized after 3.5–12 months; two cases with localized disease showed no response or insufficient response to treatment and were euthanized; four cases recovered fully with or without treatment, and one showed partial recovery without treatment; and eight cases improved whilst receiving prednisolone but required continuous low doses to maintain remission. Conclusions and clinical importance – Recognition of the different forms of sarcoidosis based on history, clinical appearance and histopathology assisted in making an informed choice between treatment and euthanasia and prevented unnecessary local treatment. Equine sarcoidosis should be included in the differential diagnosis of a localized exfoliative dermatitis of unknown origin.