Aspergillus species are saprophytic fungi commonly found in compost piles, stables, and barns. They were first described in the environment in 1729 and have been associated with diseases in companion animals since 1829. Despite the ubiquitous nature of these organisms, disease occurs in only a small percentage of exposed animals.

In general, this fungal infection in dogs is either sinonasal or disseminated. The two presentations are caused by different Aspergillus species and are clinically distinct, as sinonasal aspergillosis does not lead to disseminated infection and solitary infections outside of the nasal passageways are rare.¹

In this article, we review these two classic manifestations of canine aspergillosis and discuss the diagnosis and treatment of affected patients.

Aspergillus fumigatus is the most prevalent isolate in patients with sinonasal disease, although infection can occur with other species including Aspergillus flavus, Aspergillus niger, and Aspergillus nidulans.¹ Although disease severity varies, most dogs with sinonasal aspergillosis have marked destruction of turbinate bones and mucosa. In severe cases, destruction of the frontal bones with invasion into the periorbital soft tissues and penetration through the cribriform plate into the central nervous system may occur.

Unlike the disseminated form, canine sinonasal aspergillosis occurs in apparently immunocompetent dogs. However, there is speculation that mucosal immune dysfunction predisposes certain dogs to infection.^1-3 In addition, fungal virulence factors may potentiate infection through interference with mucociliary clearance and macrophage phagocytosis.

Sinonasal aspergillosis affects primarily mesaticephalic and dolichocephalic breeds; brachycephalic dogs are rarely affected.² Most dogs with sinonasal aspergillosis are young to middle aged, with a mean age of 4.4 years (range = 1.5 to 8 years). This is substantially younger than dogs with nasal neoplasia, with a mean age of 9.5 years (range = 4 to 12 years).⁴