The practice of not informing research personnel or data analysts to which experimental group animals have been assigned.

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What is blinding?

Blinding, or masking, is achieved when study personnel are unaware of what experimental group the animals have been assigned to.

Who can be blinded?

All research team members can be blinded. This includes, but is not limited to, animal care staff, personnel administering treatment and assessing outcomes, and data analysts.

Why blind study personnel?

Knowing which group the animals have been allocated to can introduce conscious and unconscious systematic errors. This may include how animals are handled, how outcomes are assessed and how data is analyzed.

When should study personnel be blinded and when can study personnel be unblinded?

Study personnel should be blinded from the beginning of the experiment (study subject allocation) up until the latest possible time point in the study. Ideally, all team members would be unblinded after the data is analyzed.

Study personnel may be unblinded when it is necessary to identify an animal. For example, an injury occurred during when the intervention was administered and the investigators are concerned for the health and safety of the animal. Thus, it is necessary that the investigators become unblinded in order to identify appropriate treatment to provide the animal. In this case, unblinding conditions should be outlined ahead of time and should be reported and explained in the manuscript.

Optimal Practices

Suboptimal Practices​