Introduction: Approximately 100 Million male piglets are castrated in the European Union
every year (JÄGGIN et al., 2006; HEINRITZI et al., 2008). The surgical intervention is jet
necessary to avoid boar taint that may cause an unpleasant change in taste and odour of the
meat and meat products of entire males (BINDER et al., 2004). However, the conventional
method without anaesthesia / analgesia is criticized by various stakeholders all over Europe.
Multiple options of anaesthesia and / or analgesia as well as methods without castration are
discussed (BORRELL et al., 2008). The Netherlands decided to use CO2 to anaesthetize
piglets for castration. The narcotic effect of higher CO2 concentrations, with a rapid loss of
consciousness and good analgesia, is described in literature (LAUER, 1994; KOHLER et al.
1998; SVENDSON, 2006; GERRITZEN et al., 2008). By measuring behaviour during and
after castration / handling the CO2-anaesthesia is evaluated as an alternative to conventional
castration administered by a commercially available device.
Materials and Methods: A total of 80 piglets, three to six days of age, were included in this
study. They were divided in four different treatment groups. According the group piglets were
castrated or only restraint after inhaling 70% CO2 and 30% O2 for 45 s (group KN and HN),
or castrated or only restraint without anaesthesia (group K and H). The MS Pigsleeper® (Fa.
Schippers GmbH, Kerken, Germany) was used for the application of the gas mixture. Every
piglet remained restraint in the castration device during induction (45s) and castration (15s)
period, regardless their treatment group. Defensive movements, measured in duration and
intensity, were analysed during induction and castration period. At the beginning of the
castration period piglets were tested for their surgical tolerance, by cutting the skin or testing
the dew claw reflex, respectively. Additionally defensive movements and vocalisation were
documented during castration period. After the manipulation the behaviour of every piglet
was individually observed for five minutes.
Results and Discussion: During induction the duration and intensity of the defensive
movements were higher in piglets inhaling CO2. In both groups with CO2-anaesthesia the
duration and intensity of the defensive movements during castration period were lower when
compared to the corresponding groups without narcosis (H / HN; K / KN), but in spite of the
narcosis, defensive movements were still recognized in some piglets and one quarter of the
piglets, castrated with CO2, showed vocalisation during castration. Furthermore half of the
piglets with CO2-anaesthesia had no surgical tolerance. The induction of deep narcosis with
CO2 with the device used in this study was not achieved. Piglets of both groups with CO2-
anaesthesia behaved less active after manipulation. They showed a slight reduction in changing the position and stimulating the udder when compared to the corresponding groups
without narcosis. Several other behavioural abnormalities could only or almost exclusively be
observed in groups with CO2-anaesthesia. This includes gasping, cramps, loss of balance and
The analysed parameters showed that the narcosis with CO2 using the MS Pigsleeper did not
lead to a satisfactory anaesthesia. Compared to the conventional castration, CO2-narcosis can
not be recommended to castrate piglets routinely.