1. Eighteen male sledge dogs were weighed immediately on removal from their sheltered winter quarters at Halley Bay, Antarctica (75° 31′s, 26° 42′W) and weekly thereafter for 14 weeks. The first 2 weeks they were tethered and inactive and the following 12 weeks travelled an average of 10.9 km/d fully laden. Daily energy intake during winter and while tethered averaged 18–25 MJ/d and while travelling 13.9 MJ/0d.
2. Mean weight loss during the 2 weeks of inactivity was 2.3 kg despite an energy intake almost twice the recommended requirement. During the 12 weeks travelling energy intake decreased to 13.9 MJ/d but the weight loss stopped. Weather conditions at this time were becoming progressively milder.
3. The evidence suggests that sledge dogs are capable of high levels of cold-induced and possibly diet-induced thermogenesis and that these factors, particularly the former should be taken into account when designing dog rations and feeding schedules.