Abomasal Displacements (DA's)
Also known as twisted stomachs, left displaced abomasum (LDA's), right displaced abomasum (RDA's), or abomasal torsions (AT's).
So far this year we have seen an above average number of cows with these conditions.
What are they?
The fourth stomach - the abomasum, normally sits on the bottom right hand side of
the cow's abdomen beside the rumen. When the abomasum is displaced it can cross to
the left hand side of the abdomen between the rumen and the ribs. This is an LDA
and is the most common displacement.
The abomasum can also move up the right hand side of the abdomen, an RDA. RDA's
can progress to the most serious form of displacement, a torsion.
Why do they occur?
There seems to be a combination of factors that lead to the development of DA's.
In most cases we see them in cows that have been calved, between 2 and 8 weeks
and are high producers on a diet containing a lot of concentrates and low intakes of
pasture and hay. After calving, organs that were pushed out of their normal places by
the growing calf are able to move around freely, and there are several factors that can
lead to digestive upsets. There is often a severe dietary change, high levels of
concentrates and borderline blood calcium levels.
This combination of factors leads to slower passage of material through the
abomasum, and the possibility of gas remaining in the abomasum. The abomasum
then floats usually under the rumen and up the left side getting squashed between the
rumen and the ribs, or sometimes up the right hand side.
Abomasal torsions result from the twisting of the abomasum as it rises on the right side. A lot of RDA's progress to torsions as the abomasum gets bigger and rises higher.
What do affected cows look like?
Cows with LDA's drop in production and body condition, and are commonly seen by us
after not responding adequately to treatment for acetonaemia or retained membranes.
These cows don't look very sick, and are usually just not doing as well as they should.
If left longer they can develop acetonaemia and go off their milk completely as they
continue to lose weight. Cows with RDA's initially look the same as LDA's but they can
quickly deteriorate if the abomasum twists. Then they go completely off their milk,
look full on the right side, get sunken in the eyes, appear painful in the stomach, pass
small amounts of dark to black faeces, and get weak quickly. Once twisted these cows
can die quickly, sometimes in 24-48 hrs.
What can we do to fix them?
We believe that the best treatment, in most cases, is surgical correction. This involves
opening the cow in the right flank, removing excess gas or fluid, repositioning the
displaced stomach to the correct location, and stitching it in place. Cows with LDA's
respond well to surgical correction and usually recover quickly and come back on their
milk fully. Cows that have had a LDA much longer than a week or that have lost a lot
of weight may take longer to recover and may not regain full milk production, but will
usually survive. We expect a better than 95% success rate with most LDA's. Cows
with RDA's are usually more severely affected and consequently the success rate is
lower. The major factor influencing a successful outcome is how long the cow has been
affected. Cows with AT's often have a poor prognosis due to internal bleeding and
shock.
What can you do to prevent them?
Prevention of DA's is not always easy, perhaps especially this year due to the low
growth rates and low average daily intakes of pasture.
Some points to consider are:
- Minimise sudden dietary changes from a dry cow diet to a milking diet by allowing access to concentrates before calving and continue hay after calving. If paddocks are too wet, offer hay in rings on track through July and August.
- Prevention of milkfever through the use of anionic salts before calving and limestone after calving.
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