The author is a partner and large animal veterinarian at Thumb Veterinary Services in Deckerville, Mich.
Nothing was more exciting for me as a young vet student than studying the "biology" of DAs (displaced abomasums). And, after 30-plus years of practice, I still find myself challenged with the diagnosis and treatment that cows require.

Although many cases are "routine," there are those that deserve a second look. It is quite remarkable what trouble the fourth stomach can get into!

A common occurrence
DAs on the left side (LDA) are considered one of the most common abomasal (fourth stomach) diseases in dairy cattle. Although typically seen as a fresh cow disease, they can occur throughout lactation and occasionally in nonlactating cows and heifers. In fact, I corrected an LDA on the bull "Fast Future" prior to its excellent genetic proof some 25 years ago.

Most DAs do occur in the early fresh cow. Gary Oetzel, D.V.M., University of Wisconsin School of Veterinary Medicine, commented that, on average, cows eight to 12 days in milk will represent a large percentage of cases.

When I was attending vet school, we believed the disease mainly occurred in multiparous cows. Over time, we have seen a growing incidence in first-lactation animals as well.

Cows that develop the usual metabolic diseases (milk fever, metritis, ketosis and fatty liver) are definitely at a higher risk for an LDA. Occasionally, DAs pop up in "not-fresh" animals as well. Often, this can be a secondary disease following ration changes, feed quality issues, pen moves, estrus behavior and so forth.

In the Upper Midwest, we see a slightly higher incidence in late winter through spring. This may be due to issues such as environmental conditions, more fermentable feeds in storage and less exercise, among others.

Feeding and management of the dry and fresh cow are critical. Under well-managed systems, LDA incidence can be less than 1 percent. We, as an industry, are making positive progress due to all the great changes many producers have made over the last few years in transition cow management, nutrition, and housing.

Some DAs are easily found while others sneak by. Cows with LDAs typically start to lose udder bloom in the early fresh period. Rumen fill should be assessed in the left paralumbar fossa, just behind the last rib.

At a distance, a careful eye will pick up on the shape of the abdomen from the rear. Usually, the depth from the firm rumen and the last rib will be larger than normal. The cow often stops chewing her cud and may just nibble on her feed. Her manure can be "lumpy-loose" in character. At this time, she would need a closer exam.

I don't know about you, but whenever I reach for my stethoscope, the barn becomes a surround sound auditorium of vacuum pumps, skid steers, fans and crowd gates. You need a quiet area in the fresh cow pen that allows for a "good listen." It can help foster earlier detection of disease.

Listen to the entire left side - not only over the rumen (paralumbar fossa), but also the wide, deep area under the rib cage. Simultaneously, flick one or more fingers (percussion) while listening with the stethoscope (auscultation). A typical LDA will have a "ping" sound, while rumen atony with gas will produce a lower pitched "pong" sound.

This is an important distinction, as it directs our treatment plan. Adding ballottement with your fist (like bumping for a calf) will also add splash to your ears, enhancing our ability to pick up abdominal disease. Working with your veterinarian helps to establish thorough procedures for abdominal exams.

The right side dilemma
Things get a little more involved on the right side of the cow's abdomen. Right DAs are similar to LDAs in the fact that the abomasum fills with gas and dilates. The fourth stomach is displaced from the lower right abdomen in a counterclockwise direction (from the rear of the cow) to reach the upper portion under the last few ribs and the right paralumbar fossa.

These cases follow most of the history and signs as mentioned with LDAs. In both cases, the progression of illness can range from a few hours to a few days. Cows just seem to "tough it out" for a period of time. Cattle in general are fairly stoic and do not typically show the early signs of abdominal pain (colic) that we see in other species.

At times, we see the right DAs doubling over and twisting in other directions as well. We refer to these displacements as RTAs (right side torsion) or RAVs (right abomasal volvulus), which refer to the additional rotations involved. Cows rapidly experience severe signs of depression and colic in these cases. We also find this condition affecting cows throughout lactation, even into the dry period.

These animals deteriorate quickly. They dehydrate and develop electrolyte and acid/base sickness. These cases also occasionally twist and displace the third stomach (omasum) as well. Aren't you glad we, as humans, only have one stomach to deal with?

There are many variations in the DA cow, but by combining history, clinical signs and a thorough physical exam, we are able to "fine-tune" our diagnosis and treatment options. Find a dedicated caregiver, a great cow person, on your farm who really enjoys quietly walking the pens looking for cows that are not feeling right. These folks can usually pick up the abnormal quickly, allowing for timely decisions to be made.
Enjoy your fall harvest season. This is my favorite time of the year!

This article appears on page 567 of the September 10, 2015 issue of Hoard's Dairyman.

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