A presumptive diagnosis can be based on presenting clinical signs and radiographic evidence of bony lysis within the nasal turbinates and increased soft tissue densities.
A definitive diagnosis is based on histological examination of nasal biopsies, which usually shows infiltration of nasal mucosal and submucosal infiltration with lymphocytes and plasma cells.
Differential diagnosis include foreign bodies, nasal tumors, mycotic rhinitis  (Aspergillus fumigatus, Penicillium spp), traumatic rhinitis, granulomatous rhinitis (Bartonella berkhoffii), stenotic nares and rhinitis syndrome caused by canine herpesvirus with secondary bacterial infections, which has been reported in the Irish Wolfhound.
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