Review says spontaneous regression of equine sarcoids is rare

A new review in Equine Veterinary Journal argues that spontaneous regression of equine sarcoids is genuinely rare, despite the long-standing belief in some parts of practice that certain lesions may simply disappear if left alone. Sabine Brandt, of the University of Veterinary Medicine Vienna, reviewed the available evidence and concluded that when regression does occur, it appears limited to mild occult lesions and possibly some mild verrucous lesions, not sarcoids broadly. The paper also notes a major limitation in the older literature: many reported “regressing sarcoids” were diagnosed clinically, without histopathology or BPV testing, making it hard to know how many were true sarcoids in the first place. (researchgate.net)

Why it matters: For veterinary professionals, the review is a reminder to be cautious about watchful waiting and about interpreting uncontrolled treatment outcomes. Sarcoids are the most commonly diagnosed tumor of equids, and they’re persistent, locally aggressive lesions with variable behavior and frequent recurrence after treatment. A 2024 systematic review found the treatment evidence base remains weak, with substantial heterogeneity and insufficient evidence to recommend one modality over another, meaning assumptions about “natural” regression can further muddy already difficult clinical decision-making. (merckvetmanual.com)

What to watch: Expect this review to sharpen discussion around case confirmation, lesion classification, and the need for better controlled sarcoid trials that can distinguish true treatment effect from the uncommon cases that may self-resolve. (researchgate.net)