Type 1 abomasal ulcers in dairy cattle.

Abomasa from 912 randomly selected cows were examined; specimens were obtained at the local slaughter house on 35 days spread over one year. Abomasal lesions were assessed macroscopically and histologically. Additionally, haematological and blood chemistry (urea, aspartate aminotransferase, potassium, chloride, calcium) evaluations and the determination of rumen chloride concentration were performed. Of the 912 abomasa examined, 187 (20.5%) had ulcerative lesions of the mucosa. Lesions were classified from 1 to 4 based on severity as described by Whitlock (1980). All ulcers were classified as type 1 (erosions and non-perforating ulcers); thus, further division into four subtypes 1 a, 1 b, 1 c and 1 d was carried out. Fifty-six abomasa had minimal mucosal defects which were classified as type 1 a. Deeper erosions combined with local hemorrhage, classified as type 1 b, were observed in 54 abomasa. Type 1 c were crater-like ulcers and were seen in 61 abomasa. Sixteen abomasa had type 1 d ulcers which included two forms: ulcers with radial wrinkles converging on a central point, and ulcers with perforated folds. Types 1 a and 1 c occurred mainly in the pyloric region, and types 1 b and 1 d were observed mainly in the fundic region. Type 1 abomasal ulcus could not be diagnosed based on alterations in haematological or blood and rumen chemistry values.