Displaced Abomasum

Also known as:

Twisted stomach LDA RDA

Description

This is much less dramatic than a displaced stomach in the dog, and develops chronically. The abomasum is the fourth stomach of the cow and hangs loosely by the omentum. It can move from its normal position to left displcement where it becomes trapped under the rumen or a right displacement which may result in abomasal volvulus and torsion. Rearrangement of abdominal viscera in pregnancy is thought to be an important aetiological factor, however reduced abomasal motility is thought to be the primary aetiological cause. Once the abomasum is displaced gas production by the organ continues causing distension and further displacement.

Signalment

A disease of the cow affecting mainly high yielding dairy cows on high concentrate diets. Usually occurs in the first 6 weeks of lactation. Sometimes displacemnet does occur before calving, this is in late gestation and accounts for 5% of cases.

Diagnosis

Diagnosis is made on history and clinical signs in combination with auscultation findings. Using a stethoscope the entire left and right flank should be percussed. Over the region of displacement a distinct ping will be heard. Once a ping is identified the stethoscope shoud be held over that area whist balloting the lower flank, this creates a splashing sound at the gas fluid interface which is heard as a tinkle. This confirms the presence of a displaced abomasum.

History and Clinical Signs

A typical history would be a recently calved cow with a sudden drop in appetite and milk production. Animals display general malaise and abdominal pain. On clinical exam a rapid loss of condition may be evident, ketosis, decreased ruminal activity on ausculatation. Often the left flank bulges behind ribs and the temperature may be normal or slightly raised.

Pathogenesis

• There are two manifestations of abomasal displacemet. In both the abomasum becomes trapped between rumen and abdominal wall.
  1. Ventral and to the left of rumen (LDA) - the more common presentation.

• 1. • Abomasal atony and increased gas production lead to displacement. The condition is induced by the combination of a high concentrate diet, hypocalcaemia and increased volatile fatty acids from the rumen. A displacement to the right an RDA is less common.
     • Constriction of blood vessels and trauma to the vagus nerve results in abomasal distenstion with blood-stained fluid and gas, congested mucosa and infarction.

Additionally the abomasum may rupture, causing peritonitis, shock and death.

• May be associated with secondary development of ketosis.

Treatment

Any concurrent diseases should be treated e.g hypocalcaemia, metritis, mastitis or ketosis. Conservative management can be attempted in low value animals. Rolling can be undertakne to try and manipulate the abomasum into the correct position. This technique involves casting the cow onto her right side and rolling her over whilst percussing and balloting the pings to track the movement of the gas filled abomasum. Reoccurence is likely and success rates with this are usually 30-50%. A number of surgical techniques are documented to correct the displacement. These are

• Blind toggle abomasopexy
• Right flank omentopexy
• Left flank omentopexy
• Right paramedian abomasopexy