Hyperalbuminaemia (Alb > 35.0 g / l) can be a reflection of dehydration. Clinicians have to recognise that this may be a transient and self-correcting entity in otherwise healthy and well-managed horses sampled at rest and may not merit recourse to fluid therapy. Consistent minor hyperalbuminaemia and electrolyte elevations may be used to remind management of the need for sufficient provision of water. Frank dehydration obviously necessitates correction. Hypoalbuminaemia often occurs as a result of preferential production of globulins in chronic infection, in severe gastrointestinal disease and, in rarer conditions such as renal disease. Albumin may also be lost into body cavities, e.g. in pleuritis and similar entities.