Sodium and water homeostasis and derangements

Hypernatraemia in 39 hospitalised foals: clinical findings, primary diagnosis and outcome

“…Inadequate free water intake can lead to hypernatraemia. Fielding noted that hypernatraemia is seen most commonly in foals that have not been allowed or not able to nurse or drink water, particularly foals with neurological dysfunction . Neurological disease was reported in 51.3% of the present foals with admission hypernatraemia.…”

“…Hypernatraemia has a wide range of causes but can usually be attributed to one or some combination of three causes: (a) excessive sodium intake, (b) inadequate free water intake and (c) excessive free water loss. 3,16 As with many electrolyte abnormalities, multiple factors may be responsible for the observed derangement 16 and given the retrospective nature of this study, it was not possible to definitively determine the exact cause of the hypernatraemia in each of the 39 foals.…”

“…None of the 39 foals with admission hypernatraemia in this study had received hypertonic saline, hypertonic sodium bicarbonate, milk replacer or oral electrolyte solutions prior to referral. Foals have limited ability to handle high sodium loads and mild hypernatraemia can result if foals are maintained for long periods on large volumes of traditional isotonic fluids with inadequate free water replacement . Of the 39 foals, 5 had received a 1 L bolus of balanced polyionic crystalloid fluids prior to referral, but those fluids alone were considered unlikely to have induced hypernatraemia in the foals.…”

“…This was followed by more gradual replacement of the water deficit with 10% dextrose in water, with provision of balanced polyionic crystalloid fluids for ongoing water losses. There is a potential risk of cerebral oedema and seizure activity with overly rapid lowering of the serum sodium concentration and it has been recommended that the maximum rate of decrease in the serum sodium concentration should not exceed 0.5 mmol/L/h . Regular re‐assessment of serum electrolyte solutions during the initial phase of treatment has been advised until serum sodium concentrations normalise, to allow modifications of the fluid therapy plan if required .…”

“…Foals have limited ability to handle high sodium loads and mild hypernatraemia can result if foals are maintained for long periods on large volumes of traditional isotonic fluids with inadequate free water replacement. 16,20,22,23 Of the 39 foals, 5 had received a 1 L bolus of balanced polyionic crystalloid fluids prior to referral, but those fluids alone were considered unlikely to have induced hypernatraemia in the foals.…”