Pithomycotoxicosis (facial
eczema) is a seasonal hepatogenous
photosensitization of sheep caused by the ingestion of
sporidesmin contained in the spores of the fungus Pithomyces chartarum. We describe 4 cases of obstructive rhinopathy associated with chronic pithomycotoxicosis naturally occurring in the north of Spain. Sheep were 5 to 7 years old and Latxa breed. A detailed clinical study was conducted together with computerized tomography examination and completed by necropsy and histopathology. All sheep developed a permanent narrowing of the nasal lumen close to the nostrils causing inspiratory
dyspnea and
snoring. Computerized tomography demonstrated a significant increase of soft tissue in the rostral nasal cavity. Elevated gamma-glutamyl
transferase,
alanine aminotransferase, and
lipase were noted on serum biochemistry. At necropsy, liver
atrophy and
fibrosis associated with chronic pithomycotoxicosis was identified in 3 of the sheep. All sheep had whitish elevations and rough surfaces on the alar folds and areas adjacent to the nasal surfaces. Histopathologic assessments, which included histochemical and immunohistochemical techniques, of the nasal lesions identified moderate to severe
arteriosclerosis in 21.5% to 61.9% of the small arteries evaluated with surrounding
fibrosis and
edema. No changes associated with
hypersensitivity reactions were found. These lesions were similar to the ones described in blood vessels of the liver in chronic pithomycotoxicosis and in our cases. The results of this study suggest a direct action of the
sporidesmin on the rostral nasal cavity. Further studies are needed to analyze the impact of the
sporidesmin on the sheep nasal mucosa.