In our hospital, lymphoplasmacytic rhinitis (LPR) is the third most common cause of nasal discharge second only to nasal neoplasia and nasal aspergillosis. Early studies that reported treatment response in a small number of dogs with LPR suggested that the disorder was immunemediated or allergic in origin and that steroid therapy was curative. (Burgener, Tasker) Curently, most dogs with LPR are non-responsive to steroid therapy but som are variably responsive to doxycycline or macrolides, suggecting that certain microbes may be involves in the pathogenesis of disease. We propose to initiate investigations into the roles of micro-organisms in dogs with LPR. We will use detection and quantitation of microbial DNA in nasal biopsies from dogs diagnosed with LPR and will compare these to levels found in dogs with neoplasia or nasal aspergillosis. TaqMan polymerase chain reaction (PCR) technology will be used to document and quantify biopsies of dogs. Information gained from this study will provide valuable insights into the micro-organisms that might participate in chronic LPR in dogs and will provide a rationale for the use of anti-microbial therapy in control of clinical disease.