Equine Endocrine testing
Reference: (See LabNote 56 ‘Equine PPID and EMS testing’ for a more detailed description).
2021 Equine Endocrinology group – Pituitary Pars Intermedia Dysfunction (PPID) and
2020 Equine Endocrinology group – Recommendations for the diagnosis and treatment of equine metabolic syndrome http://sites.tufts.edu/
i. Suspected thyroid dysfunction: total T4 (test code tt4), free T4 (test code ft4d), or as a panel including both (test code tprf1).
- Requires 1 mL of frozen serum shipped with a freezer pack. Do not collect blood into SST collection tubes.
- free T4 testing is batched weekly.
ii. Suspected pituitary pars intermedia dysfunction (PPID): glucose, insulin, ACTH - can be ordered individually or as a panel, test code cuin, “Equine PPID (Cushings) profile”.
- ACTH requires 1.0 mL of EDTA plasma, which should be separated immediately following sample collection, placed into a plastic tube labelled as plasma, frozen, and shipped with a freezer pack. Do not send whole blood. Note: ACTH is very heat-labile.
- For insulin and glucose, collect blood into a red-top vacutainer (do not use SST blood collection tubes), avoiding hemolysis. Allow the sample to clot, and then centrifuge. Transfer the serum into a leakproof tube labelled as serum. Refrigerate or freeze, and ship with freezer packs.
- 1.5 mL of serum is required for insulin and glucose.
- Insulin testing is batched weekly.
iii. Suspected equine metabolic syndrome (EMS): glucose, insulin - can be ordered individually or as a panel, test code insgluc, “insulin and glucose”.
- Collect blood into a red-top vacutainer (do not use SST blood collection tubes), avoiding hemolysis. Allow the sample to clot, and then centrifuge. Transfer the serum into a leakproof tube labelled as serum. Refrigerate or freeze, and ship with freezer packs.
- 1.5 mL of serum is required for insulin and glucose.
- Insulin testing is batched weekly.
- Fasting is not required, but horses should not be fed grain within 4 h prior to sampling.