Decision tree
How much blood does a rat have?
On average, rats have around 64 ml of blood per kg of bodyweight.
A rat weighing 400 g would therefore have a total blood volume (TBV) of approximately 64 ml/kg x 0.4 kg = 25.6 ml.
How to decide on the most appropriate blood sampling technique for rats?
The two tables below are designed to assist in determining the amount of blood to sample from the animal, and depending on that volume, the most appropriate techniques to use.
1. Do you require more than one blood sample from the same rat?
|
YES |
NO |
|---|---|
|
Maximum <10% TBV (= 2.56 ml) on any single occasion AND <15% TBV (= 3.84 ml) in 28 days |
Maximum <10% TBV (= 2.56 ml) |
| For repeat bleeds at short intervals, suggested limit <1% TBV (= 0.25 ml) in 24 hours AND consider cannulation |
OR terminal sample under general anaesthesia (volume unrestricted) |
2. How much blood do you require?
|
Total of <3.0 ml |
Total of >3.0 ml |
|
|---|---|---|
|
General anaesthesia required |
General anaesthesia not used |
General anaesthesia required; non recovery |
|
Sublingual vein*
|
||
* Not widely used (Zeller et al. 1998)
**Cannulation surgery performed under general anaesthesia.
# Blood may be mixed with tissue fluid.