A left displaced abomasum can be a sign a herd’s transition period needs attention. Louise Hartley talks to vet Matt Hylands of Lambert Leonard and May Farm Veterinary Surgeons about the disease.
A left displaced abomasum (LDA) is a costly condition, not only due to the drug and vet fees, but also the reduced milk yield and subsequent effect on fertility.
In theory, it can occur in any cow in any herd, but in practice, it is a disease of high-yielding dairy cows in early lactation.
Matt Hylands, from the Lancashire branch of Lambert Leonard and May, explains the condition.
The abomasum is the cow’s fourth, or true, stomach. It is the final stomach on the diet’s journey to the intestines and, like our stomach, is where a lot of chemical digestion takes place.
It lies on the floor of the abdomen on the right-hand side, just behind the lungs and diaphragm.
A displaced abomasum is seen when the abomasum moves from its normal anatomical position. An LDA occurs when the abomasum drifts over to the left of the cow and lies between the rumen and the left body wall [see below]. It constricts outflow, causing a build-up of gas and a dilated abomasum.
The exact cause is still not thoroughly understood. It is thought during pregnancy the uterus pushes the abomasum slightly to the left, which ordinarily will return to its normal position on the right immediately after calving, presumably helped by the massive rumen which naturally lies on the cow’s left-hand side.
It is well-documented a cow’s dry matter intake around calving naturally drops, meaning the rumen takes up a fraction of the space it originally did, resulting in less pressure on the abomasum to return to the right-hand side.
In addition, after calving, the abomasum can develop atony [a lack of tone], which means its contents fail to pass through, and instead gas builds up, making the chance of it drifting between the rumen and left body wall even more of a risk.
A number of different factors cause abomasal atony, including acidosis, ketosis, hypocalcaemia [milk fever], mastitis or metritis.
All these conditions are commonly encountered at or around calving and usually cause a further drop in dry matter intake, meaning an even smaller rumen and even bigger risk of a displacement.
Although LDAs make up 80-90 per cent of displaced abomasum cases, cows can also suffer from right displaced abomasums, caused by the same principles.
The most common symptom of an LDA is unsatisfactory milk yield in the cow’s first month in-milk. She may also have a loss of appetite, quite often eating forage but refusing concentrates.
Unless the abomasum is significantly bloated, or an ulcer is present, the heart rate and vital signs tend to be within normal limits.
Yes. Tapping the skin with your fingers while listening with a stethoscope along a diagonal line drawn between the cow’s left hip and elbow will reveal an area of high-pitched pinging, usually over the last rib, similar to a drop of water falling into a tin bucket [see diagram below].
Practice makes perfect, and once heard, this sound is very hard to miss.