Immunocastration - practical implications
Improvac(r) contains a modified form of GnRH. It requires two doses by injection, >4 weeks apart.
The first injection should be conducted when the piglets are 8 weeks of age or above and the second time 4-6 weeks prior to slaughter.
The dose is 2 ml and it should be injected subcutaneously with the aid of a special applicator in the dorsal part of neck immediately behind the ear.
Equipment for immunocastration. Source: Carl Brunius
Lack of boar taint can be noticed two weeks after the second vaccination and the response is maintained for about 10 weeks.
Because the immunogen is not species-specific there is a small risk to the handler during the injection of the vaccine: accidental self-injection can lead to temporary sterilization. If the handler is injected it can cause sterility in humans, as warned on the manufacturer's web site:
"Accidental self-injection may produce similar effects in people to those seen in pigs. These may include a temporary reduction in sexual hormones and reproductive functions in both men and women and an adverse effect on pregnancy. The risk of these effects will be greater after a second or subsequent accidental injection than after a first injection. The product label advises anyone who has received an accidental self-injection to seek medical attention immediately and not to use the product in the future."(Pfizer, 2010).
The problem of serious side-effects to animals and humans is further emphasized by the medical community as according to the European Medicine's Agency:
"Accidental self- injection may produce similar effects in people to those seen in pigs. The risk of these effects is greater after a second or subsequent accidental injection than after a first injection." (European Medicine's Agency, 2010).
Hennessy (2006) reported that the meat from immunocastrated pigs was more acceptable to Japanese and Filipino consumers than meat from entire male pigs. Font i Furnols et al. (2008) reported that, based on odour and flavour, Spanish consumers were unable to differentiate between cooked meat from immunocastrated pigs, surgically castrated pigs and female pigs. The consumers were not informed about the origin of the meat, so no conclusions can be drawn on their attitudes to immunocastration.
However, concerns about the effect of the drugs on animal and consumer health have been expressed and future investigations will show if this interference with the animal's natural development can be ethically accepted by consumers and citizens.