Plasma volume measurements in sheep using Evans' blue and continuous blood sampling

Area of Science:

• Veterinary Medicine
• Animal Physiology

Background:

• Accurate determination of plasma volume is crucial for understanding physiological states in sheep.
• Existing methods for plasma volume estimation can be complex or invasive.

Purpose of the Study:

• To evaluate the efficacy and safety of Evans' blue dye for determining plasma volume in sheep.
• To establish a practical method for plasma volume measurement in livestock.

Main Methods:

• Intravenous administration of Evans' blue dye (0.3-0.4 mg/kg) to sheep.
• Continuous blood collection for 10 minutes post-injection.
• Analysis of plasma dye concentrations to calculate plasma volume using intravascular dilution principles.

Main Results:

• Plasma volume values derived from Evans' blue dye concentrations closely matched those obtained using labelled macromolecules.
• No adverse effects of the dye on sheep carcase quality were observed.
• The method proved effective in standard sheep holding pens.

Conclusions:

• Evans' blue dye is a reliable and safe agent for estimating plasma volume in sheep.
• This method offers a practical and non-detrimental approach for routine use in animal research and potentially in livestock management.