Sarcoidosis is a disease complex found in several mammalian species. Specifically, equine sarcoids are the most common of tumor growths reported in horses.

Sarcoids are primarily non-malignant; they typically do not spread throughout the body, yet they do often grow larger and multiply locally. They can occur as single or multiple lesions in different forms; ranging from small, wart-like lesions to large, ulcerated and fibrous growths.