A body part cooling apparatus for regulating the temperature of a part of the human or animal body, the body part cooling apparatus comprising: a refrigeration and control unit; and a body part cooling attachment; wherein: the refrigeration and control unit comprises: a heat exchanger, a pump, an outlet connection and an inlet connection all of which are connected together via interconnecting pipe work; a first temperature sensor, a second temperature sensor and a heat transfer fluid flow rate sensor; and a controller arranged to receive respective signals from the first temperature sensor, the second temperature sensor and the flow rate sensor and to control operation of the heat exchanger, the pump, or both the heat exchanger and the pump; the body part cooling attachment comprises: an attachment part for attaching to the human or animal body, and hosing which connects the attachment part to the outlet connection and the inlet connection of the refrigeration and control unit; the heat transfer fluid is disposed in the heat exchanger, pump, interconnecting pipe work, hosing and attachment part for circulation by the pump; and the controller is arranged: to monitor the difference in temperature of the heat transfer fluid across at least the attachment part of the body part cooling attachment and to monitor the flow rate of the heat transfer fluid through the attachment part, and to calculate the heat energy removed by the attachment part over a predetermined period of time, and to control the heat exchanger or the pump, or both the heat exchanger and the pump, to control the heat energy removed from the part of the human or animal body by the attachment part based on the calculated heat energy extracted, characterised in that the heat energy extracted follows a predetermined heat transfer characteristic, the predetermined heat transfer characteristic is variable over time, and the heat transfer characteristic is determined according to a drug, drug combination and/or drug dosage to be administered to the human or animal. a refrigeration and control unit; and a body part cooling attachment; wherein: the refrigeration and control unit comprises: a heat exchanger, a pump, an outlet connection and an inlet connection all of which are connected together via interconnecting pipe work; a first temperature sensor, a second temperature sensor and a heat transfer fluid flow rate sensor; and a controller arranged to receive respective signals from the first temperature sensor, the second temperature sensor and the flow rate sensor and the refrigeration and control unit comprises: a heat exchanger, a pump, an outlet connection and an inlet connection all of which are connected together via interconnecting pipe work; a heat exchanger, a pump, an outlet connection and an inlet connection all of which are connected together via interconnecting pipe work; a first temperature sensor, a second temperature sensor and a heat transfer fluid flow rate sensor; and a controller arranged to receive respective signals from the first temperature sensor, the second temperature sensor and the flow rate sensor and to control operation of the heat exchanger, the pump, or both the heat exchanger and the pump; the body part cooling attachment comprises: an attachment part for attaching to the human or animal body, and hosing which connects the attachment part to the outlet connection and the inlet connection of the refrigeration and control unit; the heat transfer fluid is disposed in the heat exchanger, pump, interconnecting pipe work, hosing and attachment part for circulation by the pump; and an attachment part for attaching to the human or animal body, and hosing which connects the attachment part to the outlet connection and the inlet connection of the refrigeration and control unit; the heat transfer fluid is disposed in the heat exchanger, pump, interconnecting pipe work, hosing and attachment part for circulation by the pump; and the controller is arranged: to monitor the difference in temperature of the heat transfer fluid across at least the attachment part of the body part cooling attachment and to monitor the flow rate of the heat transfer fluid through the attachment part, and to calculate the heat energy removed by the attachment part over a predetermined period of time, and to control the heat exchanger or the pump, or both the heat exchanger and the pump, to control the heat energy removed from the part of the human or animal body by the attachment part based on the calculated heat energy extracted, to monitor the difference in temperature of the heat transfer fluid across at least the attachment part of the body part cooling attachment and to monitor the flow rate of the heat transfer fluid through the attachment part, and to calculate the heat energy removed by the attachment part over a predetermined period of time, and to control the heat exchanger or the pump, or both the heat exchanger and the pump, to control the heat energy removed from the part of the human or animal body by the attachment part based on the calculated heat energy extracted, the heat energy extracted follows a predetermined heat transfer characteristic, the predetermined heat transfer characteristic is variable over time, and the heat transfer characteristic is determined according to a drug, drug combination and/or drug dosage to be administered to the human or animal.