Pan-Fungal Polymerase Chain Reaction and Fungal Precipitins Assays in West Highland White Terriers with Canine Idiopathic Pulmonary Fibrosis

Abstract

peer reviewedObjective: Canine Idiopathic Pulmonary Fibrosis (CIPF) is a progressive parenchymal lung disease of unknown origin mainly occurring in old West Highland White Terriers (WH- WTs). The objective of this study was to investigate a po- tential association between fungal infection or sensitization and CIPF. Methods: A conventional pan-fungal Polymerase Chain Reaction (PCR) assay targeting the conserved rDNA gene internal transcribed spacer-2 region was performed using DNA extracted from lung tissue samples from WHWTs af- fected with CIPF (n=26) and age-matched controls (n=14). Additionally, serum samples from 8 WHWTs affected with CIPF and 8 age-matched unaffected WHWTs were tested for precipitins against 10 species of environmental fungus using electrosyneresis on cellulose acetate. Results: Fungal DNA was amplified in 8 (57%) controls and 15 (58%) WHWTs with CIPF (P=0.973). Sequences of good quality were obtained for 5 samples and matched with 97% homology with Cladosporidium spp. and Alternaria spp. in 2 distinct WHWTs with CIPF, and with Aspergillus fu- migatus, unspecified fungi, and eukaryotic DNA from a plant (Popolus spp.) in 3 distinct controls. Results of the serologi- cal assay revealed the presence of ≥ 2 arcs of precipitins in 35 (44%) reactions in the CIPF group compared with 20 (25%) reactions in control group (P=0.013). Conclusion: These results suggest that an association be- tween CIPF and active fungal infection is unlikely as fungal DNA was equally amplified from lung of CIPF-affected WH- WTs and controls. However, the higher proportion of serum positive precipitin reactions in CIPF may suggest a lung sen- sitization to inhaled fungal allergens and warrants further investigation