Effect of freezing and freeze-thaw cycles on equine serum insulin concentration
Project Abstract
Insulin is a hormone commonly measured in horses for diagnostic purposes. One common condition that horses face is insulin resistance, in which insulin receptors become less sensitive to the hormone, and insulin is not able to metabolize glucose in the bloodstream. In response, the pancreas creates more insulin, leading to increased insulin in the bloodstream, a condition called “hyperinsulinemia.” Insulin dysregulation is a key component of Equine Metabolic Syndrome (EMS), and is a precursor to other maladies like laminitis and liver failure. Horses with EMS require special dietary management to prevent the worsening of the condition, or development of irreversible side effects. Diagnosis of EMS is conducted through blood sampling measuring the concentration of insulin and glucose in the blood. Because diagnosis centers around the content of insulin in the blood, achieving an accurate result of insulin concentration is vital. An inaccurate result can lead to harmful misdiagnosis, lessening the horse’s chances of long term health.
Proper sample handling is vital so that analysis is accurate and diagnosis is correct. In a clinical setting, serum samples are sometimes frozen, yet the effect of freezing and thawing on equine insulin serum is unclear. A 2012 study evaluated the effect of freezing and thawing on equine insulin serum, and had inconclusive results. A 2016 study followed a similar procedure and found that insulin concentrations decreased after freezing, though they also had a wide range of results. Neither of these studies analyzed their samples before the first freeze.
This project aims to evaluate the effect of the initial freeze on equine insulin serum as well as the effect of two successive freeze-thaw cycles. It is hypothesized that initial freezing, as well as successive freeze-thaw cycles, will reduce the amount of insulin recovered. The results of this study will be helpful in informing sample handling in veterinary and laboratory practices.
In clinical settings, serum is most commonly used for analyzing insulin concentration. To obtain serum, this study must draw blood from live animals. The animals will be used only for blood collection, falling under Pain Category C. The student researcher will be given two opportunities to collect blood from any given horse. If they are unsuccessful, a trained faculty member will collect that sample. Ten university-owned horses will be used in this study, and no drugs will be administered to the animals for the purposes of this study. Three, 7ml vacutainers will be collected from each horse, and serum collected from those samples. Serum will be split, with some being sent immediately for analysis (Pre-Freezing), and the rest being frozen. Frozen samples will be maintained in a regular freezer (0 ℉, -18 ℃) for two days before being thawed and a sub-sample (Twice Frozen) will be collected. Serum will again be frozen, and two days later, the bulk will again be thawed and another sub-sample (Three Times Frozen) will be collected. Those samples will again be frozen, and the Twice and Three Times Frozen samples will be sent to the lab for analysis.
Funding Type
Research Grant
Academic College
Hutson School of Agriculture
Area/Major/Minor
Equine Business Management
Degree
Bacherlor's of Science in Agriculture
Classification
Senior
Name
Dr. Shea Porr
Academic College
Hutson School of Agriculture
Recommended Citation
Wallace, Molly, "Effect of freezing and freeze-thaw cycles on equine serum insulin concentration" (2025). ORCA Travel & Research Grants. 188.
https://digitalcommons.murraystate.edu/orcagrants/188