Untersuchungen zur Wirksamkeit und Gewebeverträglichkeit von Lokalanästhetika bei der Kastration männlicher Saugferkel

Analysis of efficacy and tissue tolerance of local anaesthetics
administered prior to castration of male suckling piglets Objective
of this project was to examine the efficacy and tissue tolerance of
various local anaesthetics used in castration of male suckling
piglets. Four to six days old healthy animals were randomized into
trial groups (I to IX). Animals of the control groups (I to IV)
were treated analogous to the castration groups (V to IX) but not
castrated. In groups "Handling" (I) and "Castration" (V) 15 minutes
prior to castration/fixation the piglets were fixed as for
injection but not medicated (n=28 respective n=55). The injection
volume was standardised to 0.5 ml per testes. The animals of group
II were injected intratesticularly with 0.9 % saline (n=20), the
groups III and VI received Procainehydrochloride intratesticularly
(n=21 respective n=52), groups IV and VII were injected with
Procainehydrochloride intrascrotally (n=21 each), Group VIII was
treated with Procainehydrochloride including Epinephrine
intratesticularly (n=49) and group IX with Lidocainehydrochloride
intratesticularly (n=52). Blood samples were taken shortly before
and one, four and twenty four hours after castration/fixation from
the Vena cava cranialis. One, seven and fourteen days after
castration the healing process was evaluated by a wound score. The
weight gain was established on the day of castration and then one,
seven and fourteen days after castration/fixation. During the
trials the serum cortisol level was analysed to determine
castration pain. Monitoring the group "handling" it became apparent
that the handling of the piglets, fixation and blood sampling does
not induce a rise in the serum cortisol level. Contrary to that in
the group castration (V) one hour after the castration the average
cortisol concentration rose significantly caused by the pain
induced neuroendocrine stress reaction. Four hours after castration
the cortisol level remained significantly increased compared to the
basal levels, after 24 hours the serum cortisol concentration was
back to normal. All castration groups treated with local
anaesthetics (VI to IX) showed the same level of pain induced
neuroendocrine stress reaction. The average cortisol concentration
one hour after castration showed a comparable or even higher level
as the group castration (V). In those groups four hours after
castration the cortisol level was also clearly decreased. Twenty
four hours later the concentrations were back to the base level of
each group. Moreover there is evidence that neither saline nor
local anaesthetics cause significant increase of the serum cortisol
level after intratesticular or intrascrotal injection.
Determination of glucose, CK and AST as well as CK/AST-quotient did
not lead to precise evidence about castration induced muscle and
tissue defects. The administration of local anaesthetics prior to
castration did not have any effect on the weight gain and the wound
healing process. But there was the definite finding that the
husbandry conditions influenced the wellbeing of the animals. The
results of this study lead to the conclusion that injection of
local anaesthetics shows a good tissue tolerance but the call for a
reduction of the castration pain by presurgical injection of
Procainehydrochloride or Lidocainehydrochloride has not been
justified. The recommendation is to explore more potent
alternatives to castration of suckling piglets without
anaesthetisation.