Objectives: Mold Aspergillus spp. is a common contaminant of the nasal mucosa in several animals and is the etiological agent of dog mycotic rhinitis. This disease, relatively recurrent in middle-aged dolicocephalic breeds, shows complicated and not always evident pathogenetic features; besides this, it evolves in chronic shape and sometimes it is associated to progressive osteolysis phenomena of the surrounding bone structure. The present work describes a particular clinical case, due to the young age of the dog and the fungal agents involved. Methods: An Epagneul Breton female one year old dog showed for several months sneezes attacks and muco-purulent discharge, sometimes with blood tracks, by the left nostril; it was treated unsuccessfully with antibiotics and non-steroid anti-inflammatory drugs. After the clinical examination, an endoscopy of the upper airways was performed, and through it was visualized and removed a vegetal foreign body in the lower meatus of the left nostril. Furthermore, the endoscope showed a marked disarchitecture of the turbinates and a conchal atrophy, associated with yellow-greenish and simil-caseous consistency plaques on the mucosa, probably traceable to fungal colonies. Specimens of this material were collected for bacteriological (standard culture media) and mycological (culture on Sabouraud dextrose agar and CAFC media, biochemical identification by API ID32C system) tests, together with bioptic samples of the mucosa for histo-pathological examinations. A radiographic study of the skull, to confirm the bone integrity, was also realized. Results: Bacteriological examination was positive for Staphylococcus intermedius, while mycological examination showed the development of two fungal species, the mold Aspergillus fumigatus and the yeast Cryptococcus laurentii, respectively; branching septate hyphae were demonstrated on histologic samples. Therefore, a systemic therapy with itraconazole (5 mg/kg BID per os) was prescribed; than, the dog was submitted to a topic application of 1% solution of clotrimazole after general anesthesia. Progressive resolution of the clinical findings was noticed, and an endoscopic investigation was performed after 3 weeks, showing the absence of fungal colonies. Moreover, a second topic treatment was made, while the itraconazole was suspended. One month after the end of the therapy, there were no relapses. Conclusions: The young age of the dog, as well as the positive response to the therapy, allow to hypothesize that the pathogenicity of A. fumigatus is related to the irritant action of the vegetal body, that has also brought the animal to cause a trauma to itself in the nostril region involved; this aspect could explain the fact that C. laurentii, a non pathogen yeast normally detectable on the mucosa of the first respiratory tract, found the way to grow and produce colonies. In the absence of hard tissue lesions, the persistent inflammatory stimulus expired with the extraction of the foreign body, increasing the effectiveness of the therapeutic protocol. Furthermore, the combinated systemic-topic treatment was useful to shortening the time of itraconazole administration (normally 6-7 months) and therefore to avoid its collateral effects.