*4.4. Attrition Bias*

Overall, there was a low risk of attrition bias for the included studies. Only four [9,23–25] studies were at high risk of attrition bias. One study did not analyse every animal data point [25], inappropriately removing outliers from the reported analysis. Two studies [23,24] experienced loss to follow-up due to failures in the blood collection experimental design. These data were not adequately discussed or analysed in the reported results. Finally, [9] failed to report the number of animals randomised to each group, and therefore, loss to follow-up could not be appropriately assessed. Additionally, four studies [7,10,33,35] were reported as having an unclear risk of attrition bias due to a lack of consistent reporting of animal numbers.
