Eoin Ryan of UCD Vet Hospital explains the signs, diagnosis, treatment and the control of displaced abomasum (LDA, RDA, RVA).The abomasum is the fourth stomach of ruminants such as cattle. It normally lies on the floor of the abdomen, on the right of midline. However, particularly in dairy cows post-calving, it can become displaced either to the left (LDA) or right (RDA) of the abdomen, where it tends to rise up under the ribs due to distension with gas.
It is one of the most common causes of poor appetite and reduced milk yield in the periparturient (the period from two weeks before to four weeks after calving) dairy cow.
There are a number of common risk factors for displacement of the abomasum, including cows overconditioned at calving (body condition score of 3.5 or greater) (Figure 1); subclinical or clinical nhypocalcaemia (low blood calcium); excess concentrates in relation to forage in the diet of the cow postcalving; a lack of long fibre in the diet; and a poor transition diet in the immediate postcalving period.
This happens when too many concentrates are introduced too quickly into the diet; concurrent disease, e.g. retained placenta, metritis and primary ketosis; large calves or twins leading to lots of space for movement of the abomasum; negative energy balance in the periparturient period; social and metabolic stress in first lactation cows, particularly when feed barrier space is restricted.
The Holstein breed seems to be predisposed to this condition, both due to their conformation (deep abdomens) and the metabolic stress associated with very high milk yields.
It is important to remember, however, that other breeds of dairy cows can also develop displacement of the abomasum, and the condition of right displacement and volvulus (displacement with concurrent twisting) of the abomasum (RVA) can occasionally occur in beef animals fed diets with an imbalance between concentrates and forage/fibre.
Symptoms
The classic symptoms of this condition are of selective inappetance and a marked drop in milk production in a recently calved dairy cow. By selective inappetance, I am referring to the way affected cows tend to stop eating concentrates, while continuing to eat forage (hay/silage/maize/grass), although at reduced intakes.
This selective inappetance occurs because all of these cows develop secondary ketosis, i.e. they are breaking down fat off their back as an energy source to compensate for the fact that digested food substrates are not being absorbed from the rumen or passing down to the intestines for absorption.
The physical displacement of the abomasum and its dilation with gas is painful and leads to reduced motility of all the cow’s stomachs.
The cow will quickly lose body condition and look empty due to lack of rumen fill. In some cows with LDA, the last three ribs on the left flank may be sprung outwards. If there is an RVA, i.e. displacement and simultaneous twisting of the stomach high on the right flank, cows will become very sick in the space of hours, i.e. they will develop signs of shock with sunken eyes, weakness, depression and distension of the abdomen as fluid builds up within the twisted abomasum.
While LDA is not an immediately life-threatening condition, RVA leads to death in 12 to 24 hours.
Diagnosis
LDA, RDA and RVA can all be diagnosed by your veterinary practitioner, who will auscultate ‘pings’ (high pitched metallic sounds) over the area of the displaced abomasum. They will also be able to tell if there is a right volvulus of the abomasum necessitating immediate surgery and if there is concurrent disease, e.g. retained placenta or metritis, which also needs treatment.
It must be remembered, however, that the gas within a displaced abomasum can rise and fall frequently and, therefore, there will be occasions when the vet will not be able to auscultate ‘pings’ one day, but they will be audible another day. Therefore, a suspect animal should always be checked on at least two occasions.
Treatment
Displaced abomasum can be managed conservatively but is best treated using surgical correction. Conservative management includes techniques such as rolling the cow, altering the diet and treating concurrent disease, but failure and recurrence rates are quite high.
Surgical correction (Figure 2) is very successful for LDA and RDA and has a high cost-benefit ratio, i.e. there is a 5:1 economic benefit in favour of surgical intervention.
In the case of RVA, the prognosis is poor if the cow is not discovered early and surgery performed as soon as possible (Figure 3).
Prevention
Displacement of the abomasum can be prevented by minimising the known risk factors. Attention should be given to BCS of dry cows to ensure that they calve down at BCS 3 to 3.25. The addition of long fibre to the dry cow and milking cow diets can also aid in prevention of the condition, together with the feeding of good quality dry cow minerals with adequate magnesium — one of the best preventative measures for hypocalcaemia.
Source: Irish Farmers Journal