Right displaced abomasums (RDAs) are rarely a major problem on most farms, but can be economically important due to production losses and deaths. Incidence of RDAs varies, but they are generally 10 percent or less of the total displaced abomasums seen on any farm. A RDA is an emergency situation, and producers need to recognize the clinical signs of a cow with a RDA to seek immediate help.
RDAs are more commonly seen in cows during the early fresh period (usually less than 80 days in milk), but have been diagnosed at every stage of the cow's life. My most unusual RDA was in a six-month-old heifer presented as a chronic bloat case. Her bloat was relieved, but returned within 12 hours. Fortunately, her RDA was repaired successfully, and she went on to be a great producer.
Most of the cases I have seen can be traced back to a sudden feed change, grain overload, and high-grain/low-fiber diets. With high-concentrate diets and sudden changes to these diets, there is a significant increase in the production of volatile fatty acids (VFAs) in the rumen. These VFAs move into the abomasum where they act directly on the smooth muscle, decreasing motility. With this decreased motility, there is an increase in gas formation. Rumen bicarbonate mixes with the hydrochloric acid to form carbon dioxide. Other gases, such as methane and nitrogen, are found, also.
In most cases, the abomasum will displace in one of two ways. The first is an abomasal dilatation where the abomasum floats up, causing it to "flip over" 90 to 180 degrees. This is the less severe form. The second, and more serious, is an abomasum volvulus or torsion. This involves a twisting of the organ, often involving the omasum (the third part of the forestomach), and potentially damaging the vagus nerve and blood supply to the abomasum.
Clinical signs of RDAs are generally more severe that those of the left displaced abomasum. The drop in milk production is usually more sudden, with a cow giving virtually no milk in 36 to 48 hours. The cow usually shows more evidence of abdominal pain and has an elevated heart rate, sometimes greater than 90 beats per minute. A cow with an abomasal volvulus or torsion will present with more dramatic and serious signs than a simple dilatation. The feces will be normal at first, but usually become scant. In later stages, a dark water or tarry manure is usually present.
Diagnosis is made with a stethoscope by auscultating a "ping" over the right side - the distal rib cage and/or the upper flank. Expertise is needed to distinguish the "ping" of a RDA versus small intestinal gas. I also like to ballot the lower part of the flank while listening over the area of the ping. In RDAs, you should hear a sloughing sound, like water in a balloon. The evidence of a right-side ping, a positive slough, and the other signs provide a positive diagnosis of a RDA.
Treatment must be dramatic and immediate. Time is of the essence with RDAs, since there is the possibility of decreased blood flow to the organ in torsion cases. Minutes can mean the difference between a successful recovery and an animal that must be culled. Surgical correction is the only means to correct and replace a RDA. The success rate of animals diagnosed early can be 35 percent to 80 percent. The amount of fluid present in the abomasum, the degree of abomasal distention, and the gross appearance of the abomasal tissue can be used as a guide for a prognosis.
Post-operatively, these cows may require IV fluids and other medications to correct an acidosis or alkalosis condition. If I feel we have a good chance of recovery, I also give antibiotics, anti-inflammatories like flunixin, and oral fluids with a calcium solution, electrolytes, and magox powder, since these drugs do have a withdrawal time for slaughter. If her prognosis is questionable, I'll only give IV fluids and drugs without any slaughter withdrawal times. The key for producers is to catch these cases early and call your veterinarian immediately. If your farm's LDA/RDA incidence is increasing, have your veterinarian help you find the cause and prevent these problems. You'll be dollars - and cows - ahead.
Jim Brett is a practicing veterinarian in Montezuma, Ga.