The relationship between pedicle flap width and viable length was characterised for skin flaps of the flank in ponies. Four dorsally based, pedicle type skin flaps of 20 cm in length and 3, 6, 9 or 12 cm in width were created in a random sequence on one flank in each of 10 ponies. Flap survival length was assessed by skin texture and appearance, depilation of hair and wound healing at 14 days after surgery. There was considerable variation between animals in the viable length of flaps of the same width; however, a significant difference in the viable length of flaps of different widths was detected (P = 0.002). The viable length of the 3 cm flaps was significantly different from that of the 12 cm flaps (9.69 +/- 1.1 cm vs 12.97 +/- 1.0 cm, mean +/- se P less than 0.05). There was a positive correlation between flap width and viable length (r2 = 0.141, P = 0.017). There was no effect of flap order (cranial to caudal positioning relative to the other flaps) on viable length (P = 0.286). The results of this study demonstrate a significant relationship between flap width and viable length, confirming a previously unsupported assumption that flap width and viable length are related. These findings suggest that the clinician should employ broad pedicles when using local flaps to reconstruct skin defects on the flank of the horse.