Fungal nasal disease in the dog can be caused by a fungus known as Aspergillus fumigatus. The fungus likes to live in moist warm environments like in soil. It is in the same family of fungus that is responsible for causing common black bathroom mould.
In some dogs, it can set up an infection in the nasal cavity and the sinuses. It can cause damage to the nasal cavity and this can lead to sneezing, thick green sometimes blood tinged discharge. Some dogs can develop some loss of the nasal pigment at the corner of their nose.
These are difficult infections to treat and cure and if your pet is showing any signs of sneezing or nasal discharge then they should be assessed by a vet. In order for this type of infection to be diagnosed a CT scan needs to be performed of the nose and sinuses and collection of nasal tissue is needed via rhinoscopy (scoping of the nasal cavity)
Treatment may involve a anti-fungal soaking of the nasal cavity, some dogs also require short-term placement of sinus tubes to deliver anti-fungal for 7-10 days into the nasal cavity and sinuses and often combined with oral anti-fungal treatment. Oral anti-fungal medications often don’t work well on there own so topical treatments are needed.