I need to determine the number of mice required for a LD50 assay following the Reed and Muench method.
The assay includes six groups of mice, to which a dose of bacteria from 10E8 to 10E3 will be administered:
Group 1 = 10E8 cfu
Group 2= 10E7 cfu
Group 3 = 10E6 cfu
Group 4 = 10E5 cfu
Group 5 = 10E4 cfu
Group 6= 10E3 cfu
Is there an equation to determine the number of mice needed to have statistical power? There are no previous studies with this bacterium, so there is no standard deviation data.
In that case, I think you should do a pilot experiment, and then, with the pilot's results, you can calculate your sample size.
Hello David A. Montero
Please refer to the research paper given below. It may be helpful.
https://iai.asm.org/content/iai/14/2/564.full.pdf
In vivo studies. Cell suspensions were administered to Swiss-Webster female mice (Spartan Research Animals, Inc., Haslett, Mich.) weighing between 18 and 22 g. The LD50 determinations of colony-forming units (CFU) for animals receiving living or dead cells were done by using a 15-day end point. Approximately 1,250 mice were used in this study. The final LD50 values were calculated by the method of Reed and Muench (13), using equally spaced 10-fold dilutions after a preliminary titration. At least 30 mice were challenged per LD50 value, using six mice per dose at five different dilutions.The peroral administrations into the mouse stomach of the challenging dose were achieved by intraperitoneal (i.p.) administration to each animal of an anesthesia of 70 mg of sodium pentobarbital per kg.
You can also refer to the research article given below:
Article A modified arithmetical method of Reed and Muench for determ...
Good Luck.
One way to evaluate the correct sample size is to begin with minimum numbers. 6-8 mice per group should be fine to start with for both the statistical significance and adherence to the rule of investing mice in experimentation.
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