A disease which occurs mainly, although not exclusively, in high producing dairy cows during the first 6 weeks of lactation.

AETIOLOGY

Abomasal( 4th stomach) motility is known to be reduced when cattle are fed a diet with a high fat and/or high protein content and once the abomasum becomes hypotonic it will become distended with food material and gas. It has been suggested that the abomasum moves forward and to the left under the rumen during late pregnancy when the gravid uterus causes the rumen to lift slightly from the abdominal floor, and then becomes trapped when the rumen re-expands after calving. A secondary acetonaemia usually develops.

Concentrate feeding and lack of exercise are also important factors in the aetiology.

CLINICAL FINDINGS

In the period following calving (may vary from a few days to weeks) there will be a selective anorexia (roughage eaten, concentrates refused), accompanied by a marked drop in milk yield and a ketotic smell from the breath, milk and urine.

Rectal temperature, cardiovascular and respiratory findings are all within the normal range. Quite often a concurrent septic focus may be detected e.g. mastitis/metritis/lameness etc.

Rumenal movements are reduced in frequency and strength and faecal output is reduced and slightly soft, but in some cases intermittent profuse diarrhoea may occur.

The displaced abomasum can be heard on the left flank, usually between the ninth and twelfth ribs over the upper two thirds of the abdominal wall. Abomasal sounds are typically high pitched with tinkling and splashing sounds which are often peristaltic; these sounds may be heard spontaneously or after gently ballotting the lower part of the abdomen in that area.

These sounds often disappear if an animal is moved and great care must be taken to conduct a thorough examination before a diagnosis of left sided displacement of the abomasum is ruled out, in some cases it may be necessary to re-examine the cow the next day.

TREATMENT

On diagnosis of a left abomasal displacement in a dairy cow three options are open to the veterinary surgeon:

1. Conservative treatment e.g. rolling
2. Surgical correction
3. Cull.

Conservative treatment is often employed as an initial treatment and if this fails then surgery is performed. The technique of rolling is used often but the majority of cases recur. The cow is cast on her right side and rolled on to her back. At this stage the abomasum normally tends to move towards its correct position, and can be ballotted over midline. The cow is then rolled on to her left side and the abomasum can be percussed over the right flank. She should remain in left lateral recumbency for several minutes. After rolling, the animal should be encouraged to eat as much roughage as possible. 

Culling should be considered if the cow had been marked for cull in the near future for some other reason eg. mastitis; old age; poor feet. Also if the animal has had a reduced milk yield for a long period prior to examination then even if surgery is performed she will be unlikely to perform well in that lactation.

However in almost all cases surgical correction should be the first option if economically viable. Many cows which have been successfully treated conservatively have a recurrence of the condition in the subsequent lactation and surgery should be considered. The earlier after diagnosis that surgery is performed the better the likelihood that the cow will perform to her potential in that lactation.

Cases of right-sided dilatation and torsion of the abomasum are very much less common than cases of left-sided displacement 

Prognosis in cases of right-sided dilatations of the abomasum should be very guarded as often by the time veterinary advice is called for torsion has occurred with the cow in shock close to death.

Right-sided dilatations very frequently become torsions. Some cases do however resolve spontaneously.

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