Ketosis is also known as acetonaemia. Acetonaemia is a disease of high yielding lactating cows. It is characterised by a drop in milk yield, a drop in body weight, inappetance and occasionally neurological signs. It is associated with an inadequate supply of the energy needed to sustain high levels of milk production. Acetonaemia can affect cows of any age, and any breed can be affected. It usually affects cows 3-6 weeks post calving, as this is the time when milk production peaks, but there is not a concurrent peak in appetite and dry matter intake.