An increase in testosterone levels affects the shedding of velvet which, in turn, influences the behaviour of farm-raised fallow deer bucks. Consequently, the welfare of the farmed animals can be considerably improved by controlling the timing of the velvet shedding period. The aim of this study was to analyse changes in the velvet temperature and the timing of the velvet shedding in farm-raised fallow deer bucks exposed to a modified photoperiod. A total of 28 bucks were examined. The experimental group was subjected to an experimentally modified photoperiod before the direct observations and measurements of the antler temperatures with a thermal imaging camera. The acquired thermograms were useful for analysing the stages and the rate of the antler growth and for predicting the timing of the velvet shedding. The introduction of a long-day photoperiod in spring affected the growth and ossification of the antlers as well as the velvet shedding. The optimal time for antler cutting can be planned based on the identified changes in the velvet temperature in different parts of the antler.