Photo 1: Serosal surface of forestomachs and abomasum: The forestomachs have a ribbed appearance because of severe diffuse thickening of the epithelium (hyperplasia) and massive thickening of the keratinised layer (orthokeratotic hyperkeratosis)
Photo 2: Severe, diffuse, light brown, rough thickening of the epithelium (hyperplasia) of the rumen and reticulum with moderate thickening of the keratinised layer (orthokeratotic hyperkeratosis)
Severe diffuse thickening of the keratinised layer with normal keratin layers (orthokeratotic hyperkeratosis) and partly with keratin layers with visible nuclei (parakeratotic hyperkeratosis); mild diffuse hypertrophy and hyperplasia of the epithelium caused by proliferation of the stratum spinosum (acanthosis); mild exocytosis of a few neutrophils and macrophages in the stratum basale.
Severe diffuse hyperkeratosis of the rumen and reticulum
Severe, chronic, diffuse, orthokeratotic and parakeratotic hyperkeratosis of the rumen with mild acanthosis and mild suppurative rumenitis