How much blood does a horse have?
It is breed dependant but approx 6-10% of their body weight (30-50L)
How much blood can a horse lose before it is damaging to their health?
A horse can lose approx 6L of blood safely.
If 6-12L is lost, horses can often manage without blood transfusion if appropriate care is given.
Beware of the small wound:
Last week we saw a healthy 450kg mare that had a very small cut on her RH leg. Unfortunately it had lacerated a small artery approx 5mm in diameter. The amount of blood loss had not been apparent until the next day.
She presented with signs of shock due to her marked blood loss. She needed immediate help.
She had an elevated heart rate which was compensating her reduced blood pressure to allow her vital organs to stay healthy.
This mare was lucky that her reduced blood pressure had stopped her bleeding otherwise she may not be with us today. If the artery had been larger it would likely have continued to bleed.
Her normal blood concentration with red blood cells is approx 40%. This mare lost so much blood that it was only 22%.
She received fluids to expand her blood volume artificially, these are called colloids. The leg was bandaged to prevent further bleeding, and she is now recovering really well and should make a full recovery.
Please see my photos attached for an insight into calculating blood cells in the body.