VCP 411: Medicine Section

DYE EXCRETION TEST

• Phenosulopthlein commonly used. Dye is bound to plasma protein. Most applicable for an assessment of kidney function in dogs. Remove urine by catheterization. Inject 6mg of PSP dye IV and note the time. If the animal has not been catheterized to remove accumulated urine it should be done 10 min following injection. In order to minimize the collection error rinse the bladder with 10-15ml of normal saline 3-4 times.
• Complete this procedure in 20 min following dye injection.

Calculate amount of dye – excreted

• Place all urine and dye collected from the bladder in a one – liter graduated cylinder and dilute to 400ml.
• Add 10ml of 10% sodium hydroxide and mix well. A pink color develop follwing addition of the sodium hydroxide and if is deep pink, add a sufficient water to bring the total volume to 1000ml.
• If the alkalized urine is light add sufficient water to bring the total volume to 500ml and divide the final result by 2.
• The quantity of dye excreted can be found by measurement in a spectrometer set at a wavelength of 560 nm.
• Conclusion 67% of the normal dogs be expected to excrete 33-35% of the dye in 20 min. 95% - 21-65% in 20 min. Abnormal decrease in urinary excretion of PSP occur because of poor renal perfusion due to any cause like generalized renal disease, dehydration, CHF, hypoadrenocorticism.