In humans, estrogen testing typically measures total estrogen levels (e.g. estradial, estrone, estriols) because this assesses the relevant endocrine function for human clinical diagnosis. In animals, however, the adrenal estrogens and breakdown products of estrogens (mostly alcohols) cross-react in this total estrogen assay to give spuriously high readings.

Therefore, the relevant estrogen for clinical testing in animals is estradiol, 17 beta. This assay has been validated for dogs, cats, horses, pigs and cattle. Normal serum levels for dogs and cats are: Males and Spayed Females, < 15 - 20 pg/mL; Females, varies with the stage of estrous cycle.

Note: With the heartworm season approaching, please remember the preferred specimen for heartworm testing is a Red Top tube. Lavender Top tubes can cause false positives.