Measurement of estrone sulfate by radioimmunoassay. For pregnancy detection in horses, estrone sulfate is most reliable after 60-90 days of gestation. However, concentrations may decrease a few weeks before parturition.
Measurement of serum and urine creatinine, sodium, potassium, chloride, calcium, and phosphorus by automated analyzer to determine electrolyte fractional excretion.
Specimen
0.5 mL urine and one of the following: 0.5 mL serum or lithium heparin plasma