Practical Fluid and Electrolyte Therapy and its Pathophysiological Basis

Abstract

All of us who are involved in bovine medicine and therapeutics are aware of the need for fluid therapy in many disease conditions. Intimately associated with dehydration, toxemia, gastro-intestinal disorders, and the need for fluid therapy are derangements of electrolytes and acid-base balance.

Let me first acknowledge that a whole battery of laboratory tests is impractical and probably impossible in practice. The objective of this presentation is to discuss the pathophysiology of acid-base and electrolyte disorders as they occur in bovine disease. With a basic understanding of pathophysiology, fluid therapy can be approached in a rational manner even without the benefit of laboratory tests. If those of us who can use laboratory determinations in cattle succeed in communicating our findings to those who don't, we will have come one stop closer toward making the contribution to veterinary medicine that I feel we owe.

The bovine species is somewhat unique in that both acidosis and alkalosis are common. Acidosis is a common condition in disease in all species. Alkalosis, however, is rather rare in most species but very com-mon in cattle. This is not to imply that acidosis and alkalosis per se are diseases of cattle which need to be treated. Rather, acid-base and electrolyte disorders are manifestations of disease which must be taken into account in designing a regimen of supportive therapy.

Many excellent articles have been written on the subject of practical fluid therapy. Included in many of these papers are various formulations of fluids and electrolytes for use in supportive therapy. Along such lines I really have nothing new to add. After all, the standard toward which each of these formulas strives is a standard upon which none of us can improve: that is plasma itself.

Instead, I would like to suggest that, as a starting point, two different kinds of corrective fluids are required: one for supportive therapy in cases of acidosis and the other for supportive therapy in alkalosis. In acidosis, Eltraad L.A.,* or a formula of similar composition, should be used for intravenous therapy. In the alkalotic patient, Ringer's solution or a formula of similar composition should be used. Oral fluids, designed for supportive therapy of the acidotic patient and the alkalotic patient can also be used. Fluid therapy in calf scours cases is somewhat more involved. A bicarbonate-containing solution is required for intravenous therapy. Oral therapy in calf scours cases may also be effective if an electrolyte solution which contains glucose is used.