Minipigs may be next drug model

C&I Issue 22, 2010

Specially bred miniature pigs, or minipigs, could be used instead of dogs and primates for toxicity testing and contribute to the replacement, refinement and reduction of animal testing (3Rs), a five-year European report has concluded.

A collaboration of industry, government and academic workers across Europe has shown that minipigs, a special breed of pig, which range from 12–35kg and grow to about knee height, have many advantages for drug and chemical safety and could improve drug safety testing.

The recommendations and outcome of the Rethink project were published in a special issue of the Journal of Pharmacological and Toxicological Methods (2010, 3, 157), with nearly half of the report devoted to issues of ethics and welfare.

Domestic pigs share many of their features with humans, including anatomy, physiology and biochemistry. Pigs’ cardiovascular systems, skin and digestive tract are a good models of humans’, giving reliable predictions of the toxicity of drugs and chemicals.

‘In many different areas, the pig is a surprisingly good model of human physiology and biochemistry and anatomy, even in very unlikely areas,’ says Roy Forster, a contributing author to the work.

The use of minipigs in regulatory safety testing is not a new idea. Minipigs provide better prediction of drug safety than traditional rat or dog models, but have advantages that go beyond their biological similarity to humans. Minipigs are a manageable size and are relatively sedentary. They reach sexual maturity quickly, in four or five months, meaning shorter housing periods, compared with other animals.

The motivation for the project, says Forster, was not to promote the minipig for toxicology testing but to look at the correct deployment of animal models. Better understanding of animal models means they can be used in the most effective ways and contribute to the 3Rs.

‘Regulatory guideline documents are generally open about which non-rodent animals to choose… in some cases the dog and the monkey are highlighted as first choice. It is in those areas where the guidance should be reconsidered,’ says Forster.

One additional advantage of minipigs over other lab animals is that pigs are bred commercially. There are economic incentives for farmers to better understand underlying genomics and reproductive biotechnologies of pigs that would be beneficial for both researchers and animal producers.

Additionally, there is already a good understanding of the needs of domestic pigs that is readily applicable to minipigs and there is already sufficient knowledge of how to manage their welfare, particularly in contrast to demanding animals such as monkeys.

The Rethink committee has sent out 100 copies of the report to government committees and commissions with a letter inviting them to formally review the work. The committee has already had some feedback from regulatory bodies, which ‘have received and are taking seriously the request’.

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