MarkO is correct.

"Treatment of hyperthermia consisting of measures which will rapidly lower core body temperature. However, care must be taken to avoid causing vasoconstriction or shivering. Vasoconstriction will impede heat loss and shivering will create heat."
http://www.rnceus.com/hypo/hypertreat.html

When I worked for a vet in SoCal, we got a couple cases of dogs left in hot cars every summer. While we hosed them down with cool tap water and placed cold packs around their head in their armpits and groin area, my vet warned us that they couldn't be packed in ice or immersed in very cold water. The highest rectal temp I every saw was 112F in a Springer Spaniel. Yes, he died.

Sue