Abomasum is the true stomach of the ruminants. It's major function is digestion by secreting enzymes, so diseases of this organ of
gastrointestinal tract is very important. The economic losses due to this condition are low production of milk during the disease and after surgical opertation, due to the cost of operation. On the average 80% of cows with LDA, produce 300 to 500 kilogram milk and 20% of cows with 2000 kilogram, produce less milk than other cows during a period of lactation.
This study was carried out on 33 cows that were referred to large animal clinic of faculty of veterinary medicine or at dairy farms. Clinical, hematological, biochemical and electrocardiographic findings were recorded from each case separately.
After surgical operation our clinical diagnosis was confirmed in all cases. Every case was examined closely for adhesion and local or diffuse
peritonitis. From 33 cases of DA studied in this survey, 31 were holstein, and 2 were crossbreed cows. Average age of the cows was 4.8 years. The highest incidence of DA was between 3th and 4th calving (45.16%).
From 33 cases of OA, 29 (81. 99%) had LOA and 4 (18.1 %) had RDA. (26.66%) of the cases had concurrent condition with DA, 16.66% had retained placenta and 16.66% had post partum metritis.
Haemograms revealed, 16% leuococytosis, 4% leuocopenia and 40% neutrophilia. Results of serum electrolytes analysis revealed, 50% hypochloremia, 31.81% hypophosphatemia, 22.72% hypocalcemia, 13.66% hypokalemia, 4.5% hyperphosphatemia, 18.18% metabolic alkalosis, and 9.09% metabolic acidosis.

Cardiac arrhuthmias included :22.72% bradycardia , 18.18% non-respiratory sinus arrhythmia , 13.63% tachycardia , 13.66% atrial fibrillation , 9.09% atrial premature contractiond and 4.54% sinoatrial block. It may be concluded that electrolyte variations and vagal nerve influences and acid-base abnormalities play major role in the incidence of above-mentioned arrhythmias. The most important finding is that after correction of DA(Abomasal Displacement) surgically and fluid therapy the arrhythmias returned to normal.