Cows have a specialized digestive system that helps them process their high fiber diet. They have four distinct compartments to their stomachs—the rumen, reticulum, and omasum are the forestomach compartments. The abomasum is the “true” stomach of the cow and carries out similar function to the stomach in humans.
The abomasum is suspended by a loose attachment, which means it can potentially move out of its normal position where it can fill up with gas and prevent normal flow of feed through the digestive track (abomasal displacement).
Abomasal displacements typically occur in high production dairy cows. No one knows exactly what causes the abomasum to move out of its normal position. The majority of abomasal disorders occur in dairy cows during the first three months of lactation (milk production).
Three types of commonly seen abnormal positions include:
- Left Displaced Abomasum (LDA), most common
- Right Displaced Abomasum (RDA)
- Abomasal “volvulus” (twisting) on the right side (RVA)
The abomasum can also twist around itself (called an abomasal volvulus), which can compromise blood supply to the abomasum and the affected cows become much more ill much more quickly.
- Loss of appetite
- Decreased manure production
- Decreased milk production
- Dull, depressed, loss of appetite
- High heart rate
- Large amounts of gas and fluid collection on the right side
- Minimal manure production
Your primary care veterinarian may recommend performing the following diagnostics:
- Physical examination
- Rectal examination
- Simultaneous “auscultation and percussion” or “pinging” of the abdomen. A pinging noise is heard when there is a gas-filled organ up against the body wall, such as a displaced abomasum (Figure 1).
- Passage of a nasogastric tube, through the nose into the stomach, to test the fluid from the rumen
- Blood work evaluation
In some cows:
- Fixation to the body wall may fail
- Infection may develop at its incision site
- Complication after the surgery is more likely to occur if they have other illnesses, health problems (e.g., respiratory (lung) disease) or are severely dehydrated
After surgery, return cows to the herd with no special post-operative management unless drugs were used that require a specific withdrawal time.
It is necessary to:
- Monitor the surgical wound
- Treat incisional complications, if they arise
- Treat other concurrent diseases, such as mastitis
Generally, the outcome following surgery for abomasal displacement is quite favorable, regardless of the technique chosen. Reports show short-term success rates as high as 85-95%; not known, is how the cows will do long-term.
The prognosis following abomasal volvulus is more guarded because blood vessels can be damaged when the abomasum is twisted and the cow will require more intensive therapy. Cows that are stressed and have increased heart rates (>100 beats/min.) may not do as well as those that are treated early in the disease.
Unfortunately, no one knows how to prevent the onset of abomasal displacements. Avoid rapid changes in diet. There has been some suggestion that heredity may play a role in development of abomasal displacement, so examine breeding lines closely.