Rhinosporidiosis in Cats

Rhinosporidiosis causes tumor-like masses that are pink to grey in color and may be covered with a yellow or white foci. The nasal mucosal mass is visible upon rostral rhinoscopy, unavailable to cat owners, which leaves vague clinical signs of epistaxis, sneezing and nasal discharge. As symptoms of Rhinosporidiosis mimic common conditions such as feline allergies, the nasal polyps are left untreated, growing in number and size. A fungal-induced polyp can be as small as a few millimeters to up to three centimeters in size, which may protrude from the cat’s nostril. 

The fungal infection rhinosporidiosis in cats is a nonfatal, chronic infection of the nasal mucosa specifically characterized by tumor-like epithelial proliferations within the nasal cavity. The etiologic agent to cause Rhinosporidiosis is the alga Rhinosporidium seeberi, a classified fungus of uncertain phylogeny. Believed to be contracted by mucosal contact with stagnant water sources or soil, rhinosporidiosis is an endemic in Argentina and India, but almost all reports in North America are primarily from the southern United States. Rhinosporidiosis is commonly encountered as a single sporadic case, but felines can pass the fungal to other host species such as canines, humans, birds and mammalian livestock.

Rhinosporidiosis in cats may not be fatal, but will cause a feline great respiratory distress. The symptoms a cat may display are related to the nasal blockage in one or both nostrils. Clinical signs of this fungal infection include: 

• Unilateral nasal discharge
• Sneezing 
• Wheezing 
• Reluctance to engage in physical activity 
• Labored breathing
• Open mouth breathing 

The fungal infection, rhinosporidiosis in cats is caused by the alga Rhinosporidium seeberi. This fungal organism has not been successfully cultured and the habitat this organism normally claims host to is unknown. However, it is believed that the alga Rhinosporidium seeberi is found in stagnant water sources or soil. When a cat comes into contact with these contaminated sources, it is believed the fungus attaches to the mucosal layer of the nasal cavity. It is assumed that felines with trauma to the nose, such as bite or scratch wounds, are at higher risk for contracting the infection as the open skin grants easy access for the organism.  Uncommon to North America, rhinosporidiosis is an endemic in Argentina and India, but is commonly encountered as a single sporadic case in Africa as well as South America. 

A feline presented to the veterinary clinic with rhinosporidiosis will have no significant blood abnormalities upon the completion of routine blood work, which will aid in the ruling out of respiratory viral infections. Upon physical exam, the nasal mass may be visible but the veterinarian may require the use of a rostral rhinoscopy tool to identify the lobulated, rough, pink to grey colored polyp. The appearance of the polyp is easily mistaken for other granulomatous lesions common to inflict felines such as cryptococcosis, entomophthoromycosis, or aspergillosis. Therefore, differentiating a rhinosporidiosis polyp from others requires microscopic evaluation of a biopsied sample of the located mass. The demonstration of the numerous, thick-walled spherules of the Rhinosporidium seeberi fungal agent confirms the diagnosis of the infection, rhinosporidiosis. 

The treatment choice of fungal infection Rhinosporidiosis in cats is surgical removal of the polyp(s). This surgical operation generally requires rhinotomy, as the polyps often extend into the nasal cavity. Following surgery, the veterinarian may apply gauze packs containing active agent povidone-iodine to the operated area in an attempt to minimize the rate of recurrence. The doctor may also treat your cat will long-term therapeutic drugs, such as dapsone or ketoconazole, if he or she believes the chances of recurrence are high. 

Following surgery, your cat will be restricted from physical activity and sent home with pain managing medication. Expect a follow-up appointment with the veterinarian approximately a week following the surgery, when the doctor will evaluate the feline’s recovery process. Most felines make a full recovery within a few weeks.

Surgical removal of the rhinosporidiosis polyp is a highly effective form of treatment and most felines do not have recurrent infections. However, some felines have reported recurrent cases of rhinosporidiosis as early as a two months after surgery. Treating rhinosporidiosis in cats can be frustrating and costly to cat owners, but consulting your veterinarian can help. Talk to your veterinarian about the best treatment and possible prevention option for managing rhinosporidiosis in your cat.