Anestesi vid kastration av spädgris

Abstract: An overwhelming majority of all male piglets are castrated without anaesthesia when they are very young. In Sweden this means that approximately one and a half million piglets are castrated every year. The reason the piglets are castrated is the strong and unpleasant smell and taste, the "boar taint" that the meat from intact boars sometimes exhibits. Boar taint is chiefly cause by androstenone and skatole, two compounds that are mostly produced by sexually mature boars and are accumulated in the subcutaneous fat. All boar meat does not exhibit boar taint and all consumers are not equally sensitive to the smell. Castration without anaesthesia is painful to the piglets and is increasingly being considered an important welfare issue around the world. In Norway piglet castration without anaesthesia is illegal since August 2002 and a ban on castration of piglets will take effect in 2009. It is likely that the situation in Sweden will develop in a similar way and it is therefore very important to find alternative ways of avoiding boar taint in pork. Until a suitable method is found it is possible anaesthesia will have to be used during a transitional period. General anaesthesia is not considered possible to use in Sweden because of environmental, labour welfare safety and disease control reasons. Local anaesthesia is the most promising option today. In this study the effect of local anaesthesia in the form of subcutaneous and perifunicular injection with lidocainehydrochloride (Xylocain®) was compared with a combination of cooling spray (containing ethyl chloride) on the skin of the scrotum and lidocainehydrochloride spray on the funiculi. By analysing the vocalization made by 4-7 day old piglets that had received one or the other of these treatments we compared the two groups with each other, with piglets castrated without any anaesthesia and with piglets who were only restrained and washed. The study was performed under field conditions, which in this case means that the substances used were given a very short time for onset before the castration procedure started. All three groups who were castrated vocalized significantly more in the >1000 Hz frequency range than the control piglets who were just restrained and washed. This however does not necessarily mean that the anaesthesia had no effect at all. There was a tendency that piglets who received no anaesthesia vocalized more than those who hade received one of the two forms of local anaesthesia. However, as there was a substantial difference between the lengths of time the different groups were restrained it is difficult to draw any conclusions as to the effect of the different methods of local anaesthesia.