On behalf of my colleagues, I would like to announce the publication of the following paper in Wildlife Research.
Pierre-Yves Daoust, G.Mark Fowler and Wayne T. Stobo. 2006. Comparison of the healing process in hot and cold brands applied to harbour seal pups (Phoca vitulina). Wildlife Research 33: 361-372
Abstract. Hot branding has been used for many years by researchers to identify seals from a long distance. In livestock, cold branding has been proposed as an alternative because it is thought to be less painful. The purpose of this study was to compare the healing process of hot and cold brands applied to harbour seal pups (Phoca vitulina). A total of 306 animals were each branded with a unique set of four characters: three applied for 3-5 s with an iron heated to 500C, one applied for either 10 or 20 s with an iron frozen to -175C. At three subsequent times over 10 weeks, 43, 41 and 51 animals, respectively, were recaptured, the macroscopic appearance of their brands recorded, and biopsies taken for microscopic examination. Cold brands had a faster healing rate than hot brands. However, they had less destruction of hair follicles, and cold brands applied for 20 s had more depigmentation. Regrowth of hair follicles could subsequently obscure brands, while depigmentation reduces the contrast between the brand and the surrounding fur. Cold brands applied for 20 s also had more extensive deep vascular damage, which subsequently may have resulted in deeper wounds in some animals. Yet, macroscopically, other cold brands, or portions thereof, were almost invisible. Based on this short-term study, the technique of cold branding that we used in harbour seals does not appear as reliable as that of hot branding to provide permanent legible brands.
Wayne
Dr. Wayne T. Stobo Population Ecology Division Bedford Institute of Oceanography Fisheries and Oceans Canada B2Y 4A2
Phone: (902) 426-3316 Fax (902) 426 -1506