Fungal Infection (Rhinosporidiosis) in Dogs

A disorder caused by the fungus-like microscopic organism Rhinosporidium seeberi that can attack the mucous membranes of the nasal passages and surrounding tissue, resulting in distinctive cauliflower-like growths in and around the nasal cavity which generally require surgical removal. This disorder is rare in the United States region but it is more common in the areas of Africa, India, and South America.

Rhinosporidiosis is a disorder caused by a fungus-like microscopic organism called Rhinosporidium seeberi. It can cause distinctive cauliflower-like growths in and around the nasal cavity which usually require surgical removal.

Symptoms from Rhinosporidiosis can start as soon as two weeks from exposure or remain hidden for up to six months.

• Bloody nose
• Labored breathing
• Nasal swelling
• Growths in or around the nostril 
• Growths on other parts of the body (rare)
• Runny nose
• Sneezing
• Wheezing

The distinctive cauliflower-like growths in and around the nasal cavity are classified as granulomas and are not unique to Rhinosporidiosis. Other diseases that are often characterized by granulomas can include Cryptococcosis and chronic Rhinitis.

Types

Rhinosporidiosis is extremely rare in either canines or humans in the United States but is seen more commonly in Africa, India and South America. Until recently Rhinosporidium seeberi was believed to be either a fungus or a protist, but it has been reclassified into the group Mesomycetozoea, a separate group of organisms which are closely related to both fungi and animals. It is often still generally referred to as a fungus.

Rhinosporidiosis is caused by the microscopic organism Rhinosporidium seeberi which is acquired by inhaling spores from decaying vegetable matter, contaminated soil or stagnant water. 

Circumstances that may increase the risk of your canine becoming infected with Rhinosporidium can include:

• Exposure to an infected individual
• Senior dog
• Trauma to the nose
• Weakened immunity
• Young puppy

In order to make a diagnosis your veterinarian will first ask for a full history of your pet, and will perform a general physical exam. A complete blood count, biochemistry profile, and urinalysis will generally be ordered at this time as well to check for any abnormalities, and cultures would be ordered on any usable samples. Depending on what symptoms are present, an x-ray to ensure there is no blockage in the upper nasal passages may also be justified. 

A definitive diagnosis of Rhinosporidiosis is sometimes delayed until a biopsy can be done on a relevant tissue sample to show distinct evidence of a Rhinosporidium seeberi infection. There is likely to be a large number of spores easily visible under a microscope in each of the granulomas that develop in the nasal area.

Any underlying disorders or illnesses will need to be addressed to minimize secondary infections. The lesions that have developed in and around the nasal passage will continue to grow in size and should be surgically removed under general anesthesia for the overall comfort and safety of the canine. In severe cases, the surgeon may deem it necessary to remove a portion of the nose as well.

Anti-fungal or anti-bacterial medications may be prescribed after surgery by your veterinarian to prevent further infections. Depending on your specific circumstance medications may be offered to help facilitate healing of the wound or to reduce bleeding at the site of the excision. 

Even after successful removal of any growths, the recurrence rate is fairly high, around 10%.

During the recovery period it is best to have a comfortable and quiet space available for your companion to recuperate with plenty of access to food and water. Post-surgery treatment typically lasts around 15 days and you may want to limit the activity of your pet during that time to prevent bleeding from the surgical sites. It is essential to complete the full measure of any prescribed medications to minimize the risk of relapse. Rhinosporidium seeberi is zoonotic and can be transmitted to humans. Be mindful of good hygiene habits when treating your dog to prevent getting infected yourself.