Effect of sequential bleeding on body weight gain in rats

Area of Science:

• Animal research
• Physiology
• Hematology

Background:

• Understanding the physiological impact of regular blood collection in research animals is crucial.
• Fischer 344 rats are a common model organism in biomedical research.

Purpose of the Study:

• To investigate the effects of monthly blood withdrawal on hematologic parameters and body weight gain in Fischer 344 rats.
• To determine the duration of any observed effects.

Main Methods:

• Young, mature, inbred Fischer 344 rats were subjected to monthly blood withdrawal (1.25-2.0 ml).
• Hematologic parameters and body weight were monitored over a 23-week period.
• A control group of non-bled rats was used for comparison.

Main Results:

• No significant changes were observed in common hematologic parameters between bled and non-bled rats.
• A statistically significant decrease in the rate of body weight gain was observed in rats that underwent blood withdrawal.
• The body weight difference became apparent by 3 weeks and persisted throughout the 23-week study duration.

Conclusions:

• Monthly blood withdrawal of 1.25-2.0 ml is hematologically safe in Fischer 344 rats.
• This procedure can impact overall animal growth, specifically reducing body weight gain.
• Researchers should consider the potential impact on body weight when designing studies involving repeated blood collection in this rat model.