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CHRONIC RUMINAL DISTENSION DEFINITION This condition is associated with progressive abdominal enlargement due to ruminal distension, weight-loss and a variable degree of diarrhoea. INCIDENCE Chronic ruminal distension is a syndrome and may arise as the result of several different and unrelated events. As a syndrome it is, however, most common in weaned beef and dairy calves (particularly if they are weaned on to a high concentrate diet) and elderly cows. AETIOLOGY In cattle, aged less than one year, the condition usually occurs in the absence of other obvious abnormalities and it is usually assumed to be due to a primary defect in rumenal function, under certain circumstances this has been shown to be due to low fibre in the diet. Occasionally the condition may arise as a sequel to another disorder. In mature cattle, chronic rurninal distension usually occurs as a sequel to some other abnormality. CLINICAL SIGNS Calves: There is usually a history of the problem being obvious soon after weaning but never being severe enough to warrant a special consultation. Affected animals are usually bright, afebrile and apparently maintaining a reasonable appetite. They are, however, either losing weight or also failing to keep up with the others in the group. Abdominal pain is not a feature. The abdomen is often greatly enlarged and fluid sounds may be easily elicited on ballottement of either flank. Left-flank tympany is usually present and this, in combination with the distension ventrally, gives rise to a very characteristic shape which is most obvious when the subject is viewed from behind. Diarrhoea is usually present but rarely profuse. NB. When chronic rumenal distension arises as the result of thymic lymphosarcoma, a sound diagnosis of this latter condition is usually possible following first examination. Mature Cattle: The above description will suffice for many adult cattle with chronic ruminal distension. However there are several additional factors which are worth mentioning. First, it is possible to carry out rectal examination in these animals and therefore it is possible to confirm that the abdominal distension is due to an enlarged rumen in this way and not merely the fact that other demonstrable lesions are usually associated with this disorder in adult cattle means that a full clinical examination is much more commonly helpful in adults. Thus, in some (but unfortunately not many) cases where the problem has arisen following reticular adhesions, there may be a history suggestive of an earlier traumatic reticulitis or else abdominal pain may still be present; in other cases where distension is due to upper alimentary tract cancer, questions as to the type of cow, farm of origin, quality of grazing, access to bracken, presence of oral papillomata and any other signs suggestive of such cancer should also be considered. TREATMENT Clearly the approach to treatment must depend on the age of the affected animal. Spontaneous recovery may occur in calves but there is little doubt that this may be hastened or calves may be saved by either the surgical formation of a small ruminal fistula or else the insertion of an in-dwelling rumen cannula. If the latter procedures are followed in calves without any other clinical abnormalities, the prognosis is generally good. In contrast, the prognosis for adult cattle with definite chronic ruminal distension is always bad. So often they either deteriorate due to an extension or worsening of the underlying cause of the problem (e.g., in the case of upper alimentary tract cancer) or else they reach a stage of sub-optimal health with impaired productivity (e.g. in the case of chronic reticular adhesions). Hence, early slaughter should be advised for all cases unless there is a good case to consider some other approach and any surgical manoeuvre must be carried out on the strict understanding that the prognosis is likely to be very poor. |
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