Wrap the dog in a thick cloth or towel to conserve body heat. If the dog is unconscious, keep its head as low as, or lower than, the rest of the body. Gently massage legs and muscles to maintain circulation unless you suspect that they may be fractured or broken. If the dog is conscious and restless, keep it horizontal and well wrapped up. Get to the vet's surgery promptly.
Time is vital, especially for the intravenous introduction of fluid in severe cases.
Don't give anything by mouth if the dog is unconscious, convulsing or vomiting. Take pulse and breathing rate every 30 minutes and record them. Note any blood in urine etc, and report these details to the vet. This often occurs if the dog is kept shut up in a house or car without shade, ventilation or water. Signs are panting, slobbering, vomiting and diarrhoea, raised temperature and ultimately collapse and coma.