Equine Rhinosporidiosis is a chronic infection caused by the Rhinosporidium seeberi organism which is of parasitic nature. It is characterized by single or multiple, painless, slow-growing, and noninfiltrating masses which are most commonly found within the nasal mucosa and occasionally the ocular mucosa.

Rhinosporidosis is endemic in India and Sri Lanka but has been reported to have previously occurred in the United Kingdom, South America, United States and South Africa.