Displaced abomasum

What it is

In the adult, the abomasum rests on the abdominal floor, mostly to the right of the median plane. When it loses motility (abomasal atony) and accumulates gas, it rises and is displaced:

• Left displaced abomasum (LDA): the most common form. The abomasum passes under the rumen and rises between the rumen and the left abdominal wall. It obstructs transit only partially and does not compromise blood supply, so it progresses slowly.
• Right displaced abomasum (RDA): the dilated abomasum rises on the right side, next to the right abdominal wall.
• Abomasal volvulus: the right-displaced abomasum rotates on an axis that runs through the lesser omentum, often together with the omasum (omasal-abomasal volvulus). Transit and blood supply are obstructed: the abomasum fills with fluid and sequesters hydrochloric acid, chloride and potassium, leading to dehydration, hypochloraemic, hypokalaemic metabolic alkalosis and ischaemia of the wall. It is a surgical emergency.

It is regarded as a transition period disease: the drop in feed intake around calving, a ration rich in concentrate and poor in effective fibre, hypocalcaemia, ketosis and postpartum inflammatory diseases (metritis, retained placenta, mastitis) reduce abomasal motility, and after calving the uterus leaves free space in the abdomen.

Who it affects

Mainly high-yielding dairy cows, particularly of breeds such as the Holstein, in the first month after calving. RDA and volvulus are less common than LDA and can occur at any stage of lactation. It is rare in beef cattle.

Anatomy involved

• Abomasum: the fundus and body rest on the abdominal floor, ventral to the omasum and caudal to the reticulum; the pyloric part rises on the right to the pylorus. It is held only by the greater omentum (on the greater curvature) and the lesser omentum (on the lesser curvature), so it is quite mobile. When it moves to the left it becomes trapped between the ventral sac of the rumen and the abdominal wall; at surgery it is fixed in its normal position through the omentum (omentopexy) or the abomasal wall itself (abomasopexy).
• Omasum: lies on the right, cranial to the abomasum, and communicates with it through the omaso-abomasal orifice. In volvulus the twist occurs near the omaso-abomasal junction and can drag the omasum along, which worsens obstruction and ischaemia.

Clinical signs

• LDA: reduced appetite, often more marked for concentrate than for forage, drop in milk yield, secondary ketosis, scant and sometimes pasty faeces. Simultaneous auscultation and percussion over the dorsal third of the last left ribs reveals a high-pitched metallic sound ("ping"). General condition is usually only mildly affected.
• RDA: similar signs, with the ping on the right side.
• Volvulus: sudden onset, complete anorexia, colic, tachycardia, dehydration, distended right abdomen, scant dark faeces; on rectal palpation a distended viscus may be felt in the right caudal quadrant. Without surgery the cow deteriorates quickly.

Diagnosis

• Auscultation with percussion (ping) and auscultation with succussion (fluid splashing sound). The ping is not specific to the abomasum: on the left it can also come from rumen gas or pneumoperitoneum, and on the right from caecal dilatation or gas in the colon or duodenum.
• Ultrasonography of the flank: shows the abomasum, with its contents and folds, between the rumen and the left abdominal wall.
• Laboratory: blood or milk ketone bodies (β-hydroxybutyrate), calcium, and in RDA and volvulus acid-base status and electrolytes (hypochloraemic, hypokalaemic alkalosis). Preoperative L-lactate helps establish the prognosis of volvulus.
• Definitive confirmation is at laparotomy.

Treatment and prevention

• LDA: the abomasum is repositioned and fixed. Closed techniques (rolling the cow, with or without percutaneous toggle fixation) are quick and cheap, but they are blind, and rolling without fixation has a high recurrence rate. Open techniques are right flank pyloric omentopexy, left flank abomasopexy and right paramedian abomasopexy; there are also laparoscopy-assisted techniques.
• RDA and volvulus: right flank laparotomy, emptying of the abomasum, repositioning and omentopexy, with fluid therapy to correct dehydration, hypochloraemia and hypokalaemia.
• Concurrent diseases (ketosis, hypocalcaemia, metritis, mastitis) must be treated at the same time.
• Prevention: transition cow management; maintain dry matter intake around calving, enough effective fibre in the ration, avoid cows calving overconditioned, prevent hypocalcaemia and monitor subclinical ketosis. Monensin reduces the risk, where its use is authorised.
• Drug use in food animals is subject to each country's regulations and to withdrawal periods for milk and meat.

Key studies

• Duffield et al. (2009), cohort of 1010 Holstein cows from 25 Ontario farms. Serum β-hydroxybutyrate ≥ 1200 µmol/L in the first week postpartum was associated with a higher risk of displaced abomasum (OR 2.60), and in the second week, at a threshold of ≥ 1800 µmol/L, the risk was higher (OR 6.22). The farms were mainly tie-stall herds feeding concentrate separately, which limits extrapolation.
• Duffield et al. (2008), meta-analysis of 16 studies with about 9500 cows: monensin reduced the risk of displaced abomasum (RR 0.75) and of ketosis (RR 0.75). Monensin is not authorised for dairy cows in every country.
• Sterner et al. (2008), cohort of 810 Holstein cows with LDA. At 60 days, 79% of those corrected by a veterinarian with roll-and-toggle, 71% of those corrected the same way by farm staff and 73% of those operated by laparotomy were still in the herd. Mastitis, a previous LDA, a high preoperative risk and correction by farm staff were associated with leaving the herd. Groups were not randomised.
• Seeger et al. (2006), randomised trial in 120 cows with LDA: laparoscopy-assisted abomasopexy versus right flank omentopexy. Success was almost equal (59 of 60 versus 60 of 60); laparoscopy was shorter (median 27.5 versus 38 minutes) and intake and milk yield recovered faster over the first 5 days, but there were 2 relapses and 5 wound complications, versus no relapses and 2 complications with omentopexy.
• Canatan and Aslan Canatan (2026), systematic review and meta-analysis of 10 studies with 2900 cows (3 randomised trials). Overall, minimally invasive surgery was associated with lower mortality (RR 0.65) and more milk (1.76 kg/day more), but when the analysis was restricted to the randomised trials there was no difference in mortality (RR 1.27; 95% CI 0.39–4.07). There were no differences in recurrence, complications or surgical time. The supposed survival advantage of minimally invasive techniques rests on observational studies. Volvulus was not evaluated.
• Boulay et al. (2014), cohort of 102 cows operated on farm for RDA or volvulus. Preoperative plasma L-lactate predicted a poor 30-day outcome better than heart rate (area under the curve 0.92 versus 0.77). At a cut-off of 2 mmol/L, sensitivity was 76.2% and specificity 82.7%; a value of 6 mmol/L or more had a specificity of 97.5%. The outcome was based partly on the farmer's satisfaction reported by phone.