An adult mixed-breed dog had a history of chronic sneezing and nasal discharge. A solitary deep-purple nasal mass was noted on examination, and a section was sent to the VDL for histology. Microscopic evaluation of the mass showed irregularly hyperplastic and polypoid mucosa. The submucosa was markedly expanded by chronicactive inflammation that often surrounded ruptured and intact variably sized sporangia occasionally containing numerous endospores. These features are consistent with Rhinosporidium seeberi infection. Rhinosporidium seeberi is a member of the Mesomycetozoa (DRIP clade of aquatic protistan parasites) and is an uncommon cause of rhinitis in dogs, horses and humans. The organism is difficult to culture and is considered potentially zoonotic. Rhinosporidiosis generally presents as a unilateral strawberry-colored nasal mass. It has been reported in at least two other dogs in the upper Mississippi River valley that had no extensive travel history . Complete surgical excision is typically curative.
This case report and others are also available in the Spring 2019 newsletter.
Heidi Pecoraro, DVM, PhD, Diplomate, DACVP
Hill et al. J Am Anim Hosp Assoc. 2010 Mar-Apr;46(2):127-3