Left Displaced Abomasum (LDA) is a condition in which the abomasum (see biology of the rumen) moves into the empty space left after calving. Usually situated on the lower right hand side of the abdomen, in LDA the abomasum moves to the upper left side of the abdomen, causing problems with digestion and gut flow.
Often after calving cows are switched to a high grain diet to meet the sudden demands of lactation, but grains are easily digested and reduce the overall volume of the rumen compared to high forage diets with repeated rumination. Ideally after calving the rumen would move into the space in the abdomen, replacing the calf, although if the rumen is not large enough the abomasum can easily fill the position first. Poor rumen function resulting from a sudden transition in diet post-calving can also lead to partially digested food entering the abomasum, continuing to ferment and release gas further pushing the abomasum out of position. Constriction of the abomasum between the rumen and abdominal wall prevents the escape of gases, causing the abomasum to increase in volume with limited normal digestion taking place. These conditions result in reduced appetite, a sudden decrease in milk yield and secondary ketosis, all of which are symptoms of LDA.
Diagnosis of LDA is usually performed by a veterinary surgeon using a stethoscope placed on the left side of the animal’s abdomen listening for a pinging noise. This noise is indicative of a gas-filled organ and can usually lead the vet to determine the presence and location of the displaced organ. Treatment of LDA usually involves an operation performed by a vet to move the abomasum to its correct position and prevent it returning, although some success can be had in conservative treatments such as “rolling” the cow to encourage the abomasum to slide back into place.
Prevention of LDA is simple if you know what causes it and how to prevent it. Transitioning cows to their lactation diet a few weeks before calving gives the rumen time to adjust to the new diet and prevents poor digestion in the days following calving. It’s also recommended to take measures to avoid acidosis around pregnancy such as introducing quality forages to stimulate rumination.