Summary This report describes a case of severe hypophosphataemia associated with the management of hyperlipaemia in a miniature pony following colic surgery. Clinical signs attributed to hypophosphataemia included obtundation, anorexia, tachycardia, tachypnoea and generalised muscle fasciculations. Hyperlipaemia was managed with enteral and partial parenteral nutrition; insulin was also administered to control hyperglycaemia after the initiation of caloric support. Specific therapy for hypophosphataemia consisted of parenteral potassium phosphate at 0.03 mmol/kg bwt/h (i.v.). The pony made a full recovery without further complications. Hypophosphataemia may be an under-recognised clinical problem in certain populations of critically ill equids, such as those with hyperlipaemia and receiving insulin as part of their management. The routine measurement of phosphate concentration in these cases is recommended.