Equine Endocrinology Assay Services

Person working in a lab

We offer a range of diagnostic endocrine tests for clinical use. Veterinarians may submit samples through the New Bolton Center Clinical Laboratory using the Equine Endocrinology submission form. 

See the shipping section of our FAQ for information about our new $25 flat-rate courier shipping labels.

Available Diagnostic Tests:

INDIVIDUAL ASSAYS

SAMPLE TYPE

Insulin

Serum

Subsequent insulin

Serum

ACTH

EDTA plasma

Progesterone

Serum

Adiponectin

Serum

Bile acids

Serum

COMBINATIONS/PANELS

SAMPLE TYPE

Single insulin and single ACTH

Serum and EDTA plasma

Single insulin and single adiponectin

Serum

Insulin monitoring (x 5 samples)

Serum

Endocrine panel (ACTH, insulin, adiponectin, glucose)

Serum and EDTA plasma

Insulin dysregulation treatment panel (insulin, glucose, adiponectin, triglycerides, bile acids)

Serum

Sample handling

    • Follow the guidelines below prior to shipping on ice: 
      • Serum – Red top vacutainer; allow clot formation (30-60 min at room temp), centrifuge after clot forms, transfer supernatant to a leakproof tube and discard red cells. Label new tube with owner, animal ID and as “SERUM” 
      • Plasma – Purple top EDTA vacutainer; gently invert to mix, centrifuge ASAP, transfer supernatant to a leakproof tube and discard red cells. Label new tube with owner, animal ID and as “EDTA PLASMA”
      • Refrigerate or freeze samples and ship with freezer packs or on wet or dry ice. Do not send whole blood.

Frequently asked questions

  • What is the protocol for oral sugar testing?
    1. No grain for 4 hours prior, access to hay is fine.
    2. Take a baseline blood sample for insulin concentration.
    3. Give 0.15 mL/kg bwt corn syrup (Karo Syrup Light with the red label) orally via dose syringe.
    4. Take a blood sample at 60 min and at 90 min after the oral sugar dose for insulin concentration.
  • What blood tube type is needed for different tests?
    • Insulin – red top vacutainer
    • ACTH – purple top EDTA vacutainer
    • Adiponectin – red top vacutainer
    • Progesterone – red top vacutainer
    • Bile acids – red top vacutainer
  • For insulin measurement, how should I process / handle samples?
    • Collect blood in a red top vacutainer. Allow clot formation (30-60 min at room temp), centrifuge after clot forms, transfer supernatant to a leakproof tube and discard red cells. Label new tube with owner, animal ID and as “SERUM”
  • For ACTH measurement how should I process / handle samples?
    • Collect blood in a purple top EDTA vacutainer; gently invert to mix, centrifuge ASAP, transfer supernatant to a leakproof tube and discard red cells. Label new tube with owner, animal ID and as “EDTA PLASMA”
  • What address do I ship the samples to?
    • Please ship to: University of Pennsylvania – New Bolton Center
      Attn: van Eps Lab – Myrin 106
      382 W Street Road
      Kennett Square PA 19348
  • Should I withhold feed (fast) before blood sampling for insulin measurement?
    • It is generally more useful to get a non-fasted blood sample, either randomly across the course of the day, or 1-2 hours post feed/pasture access.
  • How long after feeding should I wait before blood sampling for ACTH measurement?
    • Feeding has minimal effects on baseline ACTH measurement.
    • A TRH stimulation test should not be performed within 4 hours of grain consumption or oral sugar testing.
  • Can stress and/or pain affect results?
    • Stress or pain can increase insulin and ACTH concentrations in the blood and this should be taken into account in horses and ponies with active laminitis in particular. However, the increases are relatively minor and unlikely to affect the diagnosis of insulin dysregulation or PPID in most cases.
  • What is adiponectin?
    • Adiponectin is a marker of insulin dysregulation/EMS and laminitis risk. It is a key regulator of glucose and lipid metabolism and has insulin sensitizing, anti-inflammatory and antioxidant effects. Unlike leptin, low adiponectin is strongly associated with insulin dysregulation and laminitis risk (not just obesity). Low adiponectin is an independent risk factor and relatively strong predictor of laminitis.
    • Adiponectin concentrations are unaffected by stress/feed/grain access prior to sampling and therefore may be a more reliable indicator of metabolic status and laminitis risk than single insulin measurements. If possible it is ideal to measure both insulin and adiponectin when screening and monitoring horses and ponies. Management including diet, weight loss, exercise and medication can improve adiponectin concentration over time.
    • Further reading on adiponectin below.
      • Menzies-Gow NJ, Knowles EJ, Rogers I, et al. Validity and application of immunoturbidimetric and enzyme-linked immunosorbent assays for the measurement of adiponectin concentration in ponies. Equine Vet J 2019;51:33-37.
      • Menzies-Gow NJ, Harris PA, Elliott J. Prospective cohort study evaluating risk factors for the development of pasture-associated laminitis in the United Kingdom. Equine Vet J 2017;49:300-306.
      • Knowles EJ, Elliott J, Harris PA, et al. Predictors of laminitis development in a cohort of nonlaminitic ponies. Equine Vet J 2023;55:12-23.
      • Elliott J, Bailey SR. Consequences of adiponectin deficiency: Can they be related to the pathophysiology of laminitis? Equine Vet J 2023;55:346-349.
  • How do I interpret insulin and adiponectin results on a single resting sample?
    • Normal insulin and normal (high) adiponectin.
      • Although dynamic testing (OST or post-feed) could be performed, the combination of normal adiponectin and normal insulin on a non-fasted resting sample is a strong indication that the animal is metabolically healthy and has a low risk for laminitis.  It may still be worthwhile considering continued annual screening depending on breed, age, body condition and other factors.

    • High insulin and low adiponectin.
      • This is strongly supportive of ID/EMS, even without dynamic testing.
      • In all cases, feed and management changes should be initiated.
      • In cases where the resting insulin is only mildly increased (<50 uIU/mL) further testing with OST or post-prandial insulin testing (2 hours post hay/grain/pasture access, 1 hour post ration balancer) is indicated.
      • In severely hyperinsulinemic animals (>100 uIU/ml) it is ideal to first confirm the hyperinsulinemia on at least one more sample prior to considering initiating pharmaceutical therapy to help reduce blood insulin.
    • Normal insulin and low adiponectin.
      • This result may be best viewed as a warning that the horse is more likely to become hyperinsulinemic at other times (especially in response to feed/pasture high in non-structural carbohydrate).  Although adiponectin is very stable (not affected by feed/ stress) insulin is very dynamic, so a one-off sample is often not representative.
      • A low adiponectin may also make a horse or pony more susceptible to laminitis as a result of high insulin (based on evidence from pony studies, low adiponectin is an independent risk factor for laminitis - independent of ID status).  Similar to humans with metabolic syndrome, adiponectin may be somewhat protective against the deleterious effects of EMS/ID in horses and ponies.
      • In these cases further insulin testing is indicated: OST or post-prandial insulin (2 hours post hay/grain/pasture access, 1 hour post ration balancer).  This will tell you how worried you need to be about insulin under the current management conditions – and how concerned you need to be if there is pasture access particularly in spring/summer. If this further testing is normal then there is no need to act further, but regular monitoring (at least yearly) is indicated.  If OST/post-feed insulin is high then consider feed/management changes etc. to address it.
    • High insulin and normal (high) adiponectin.
      • A mild increase in insulin (<50uIU/ml) with normal adiponectin warrants further insulin testing : OST or post-prandial insulin (2 hours post hay/grain/pasture access, 1 hour post ration balancer) to guide further decision making. It is important to note that this result may be due to stress/transport/sedation or feed access prior to sampling causing a transient mild increase in insulin - insulin is dynamic and readily affected by these factors, whereas adiponectin is much more stable.
      • In severely hyperinsulinemic animals (>100 uIU/ml), regardless of adiponectin result, management/feed change and medication to help control insulin should be considered immediately - it is ideal to first confirm the hyperinsulinemia on at least one more sample prior to initiating therapy. Severe hyperinsulinemia with normal adiponectin is an extremely rare combination.
  • How do I access $25 flat rate shipping labels?

    • The van Eps lab is pleased to offer clinicians the ability to, at their convenience, request and print discounted $25 priority overnight sample shipping labels. Clinicians from anywhere in the continental United States can register to become “Collaborators” in our eShip portal, at which point they will be able to log in to their personal account to create and print priority overnight shipping labels through FedEx or UPS.

      UPS Biological Specimen Packaging Requirements 
      FedEx Biological Specimen Packaging Requirements

      To register to become a collaborator, please fill out the following form and a member of the van Eps lab will email you to finish activating your new account.

       

For research/bulk assay enquiries please contact Jeaneen Kulp: jckulp@vet.upenn.edu