Abomasal Displacement

Abomasal Displacement is the displacement of abomasums from its normal anatomical position; it may be towards the right or left side, but clinical signs are the same for both types.

The normal position of the abomasum is the mid-ventral line on the floor of the abdomen, slightly towards the right side.

Abomasal Displacement may be on the left side, which is called left displacement of abomasum (LDA), or on the right side, which is called right displacement of abomasum (RDA).

LDA is the most common among these. This is an abomasal disorder where the abomasum is displaced towards the left side and is trapped between the rumen and the left abdominal wall.

Etiology

Atony of abomasum and accumulation of gas resulting in distension of abomasum are the primary causes responsible for displacement, and there is always a link between a high incidence of LDA and a low-roughage, high-concentrate diet.

Precipitating factors

• Immediately after parturition, the incidence is higher (3–4 days postpartum).
• Immediately after parturition, the animal is lifted from roughage to a high-concentrate diet responsible for the hypertonicity of abomasums (increased volatile fatty acids).
• During pregnancy, the rumen is shifted slightly by the gravid uterus, so the abomasum is free to move on the abdominal floor, so it moves to the left side. But after parturition, involution of the uterus allows the rumen to assume its original shape on the abdominal floor; hence, abomasum is trapped between the rumen and the left abdominal wall.
• Rarely, the condition is also noticed in heifers due to oestrus during mounting.
• In breeding bulls, mounting displacement is also seen, but this is also rare.
• Post-partum hypocalcemia is also one of the precipitating factors for the occurrence of LDA, which contributes to abomasal hypomotility.

Changes associated with displacement

Compression of abomasums results in abstruction-like syndrome. It is estimated that a cow weighing about 400–450 kg can accumulate 35 litres of fluid in a trapped abomasum. Biochemically, there is a loss of chloride due to increased secretion of HCl, resulting in hypochloremia and, over time, hypovolemia. Systemically, there is ongoing dehydration and metabolic alkalosis, and in untreated cases, there could be signs of shock. In right-side displacement, the dilated trapped abomasum can undergo a 180-270° clockwise or anti-clockwise twist, resulting in an abomasal volvulus that is life-threatening.

Trapped abomasum stops further forward passage of ingesta, indicating a true obstructive episode.

Clinical Signs

Prolonged anorexia, a drop in milk production, signs of ketosis (due to an energy deficit) like a sweet smell in the urine, and loss of condition. This is called secondary ketosis. Distension of the mid-finger depends on the left or right displacement, which resembles balloon-like enlargement.

The condition is further confirmed by simultaneous auscultation and percussion over the distended organ or area between the 9th to 12th intercoastal spaces in an imaginary line drawn from left midflank to elbow. Typical high-pitched resonance sounds are heard and are called ‘ping’ or ‘pebble in well’ sounds. Other signs are the passing of scanty faeces, discomfort, and abdominal pain.

Abomasal volvulus in RDA reveals a sudden onset of abdominal pain, crouching, and tachycardia, followed by recumbency and death within 36–48 hours due to shock and dehydration.

Diagnosis

• Based on the history of recent calving.
• Based on the clinical signs
• Simultaneous percussion & auscultation at 9–12th intercoastal space with evidence of ping is characteristic.
• Lab investigation (hypochloremia, increased PCV, Liptak test)
• Laparoscopy: highly torturous vascular and pink colour differentiates abomasum from rumen.
• Exploratory laparotomy.

Differential Diagnosis

• Primary ketosis: ketonuria is severe; give response to glucose therapy without relapse.
• Traumatic Recticulo Peritonitis (TRP): winged elbows, grunt on palpation, fever are indicative.

Treatment

• Calcium supplementation improves the tonicity of abomasum (calcium boro gluconate at 200–400 ml IV or SC). Tonicity causes the flow of abomasal contents, leading to a decrease in the size of the abomasum, and the abomasum may return to its normal site.
• Concentrate diets should be stopped, and roughage feeding is advised.
• Fluids and electrolytes: ionic NaCl, depending upon dehydration, reduces metabolic alkalosis.
• Oral administration of mineral oil (3-5 liters) mixed with Mg(OH)₂ (500 gm).
• The rolling of animals has been tried with good results. In LDA, animals are laid down on left lateral recumbency with forelimbs and hind limbs tied separately. With a sudden jerk, animals are brought into dorsal recumbency, and with a similar jerk, they are rolled onto the right lateral recumbency.
• Surgical interventions like right paramedian abomasopexy and right paralumbar omentopexy can be performed.