Hi,

Generally n=8 will be better, Becasue you may lose animals during chronic study or may find some statistical outliers at the end of study.

Thank for the info......It seems that our ethical committee loves rats more than us .

I would suggest, since you want higher number of animals, find similar studies (for example similar cancer model that is testing other drugs etc) take that and go to statistician who will determine the power of your study compared to examples and take that to the ethical committee. They usually wont argue with statisticians and presented statistical power of the study :) good luck

Thanks Mr Antonic. Though I already applied once, i will apply to reconsider it.

hello,

commonly people used minimum 6 no of animals to show the effect of any treatment.so 6 number is pretty good,

I am sending you our experiences with 8 animals in a group.

Potential hepatoprotective effects of fullerenol C60(OH)24 in

doxorubicin-induced hepatotoxicity in rats with mammary carcinomas,Rade Injac a,*, Martina Perse b, Natasa Obermajer a, Vukosava Djordjevic-Milic c, Matevz Prijatelj d,

Aleksandar Djordjevic e, Anton Cerar b, Borut Strukelj

Biomaterials 29 (2008) 3451–3460

Thanks Mr. Djordjevic

As with any animal study it is vital to know the size of the effect you want to see, and take into account the variability you are likely to encounter between animals independent of treatment. Power analysis can help you determine the sample size needed. The best ethical argument is that if your experiment has insufficient power, you will not be able to prove anything staististically, and therefore the animals you have used are wasted. If power analysis suggests you can have 5 animals, then great. If not, make a robust statistical case for more. Good luck! Ed