Effect of Freezing and Freeze-thaw Cycles on Equine Serum Insulin Concentration: A Pilot Study
Academic Level at Time of Presentation
Senior
Major
Animal Science
List all Project Mentors & Advisor(s)
Dr. Shea Porr; Dr. Lydia O'Sullivan
Presentation Format
Poster Presentation
Abstract/Description
Insulin dysregulation is a key component of Equine Metabolic Syndrome (EMS), and is a precursor to other maladies like laminitis and liver failure. Diagnosis of EMS is conducted through blood sampling measuring the concentration of insulin and glucose in the blood. Achieving an accurate result of insulin concentration is vital for diagnosis, making proper sample handling essential. The aim of this project was to evaluate the effect of repetitive freeze-thaw cycles on equine serum insulin concentrations. Serum was collected from 10 university-owned horses and split into four treatment groups: Unfrozen, Once Frozen, Twice Frozen, and Three Times Frozen. Unfrozen serum was sent immediately for analysis and the other samples were maintained in a regular freezer (0 ℉, -18 ℃) for the freeze-thaw process. Once the freeze-thaw process was complete, all frozen samples were sent to the laboratory for radioimmunoassay analysis. Data were analyzed using the MIXED procedure of SAS. The concentration data were analyzed for main effects of sex, age, and freeze-thaw cycle. There was an effect of age on serum insulin concentration (P < 0.0001). Older horses had higher concentrations than younger (28.7458 ± 1.7998 uIU/mL and 51.6967 ± 2.3236 uIU/mL, respectively), which was in agreement with other published results. There was no effect of freeze-thaw cycles, which was similar to previously reported studies in other species. There was also no effect of sex, which was not in agreement with previous reports where mares were reported to have higher serum insulin concentrations than geldings. The results of this study will equip veterinarians and laboratories to freeze equine insulin serum samples up to three times and still be confident of an accurate result.
Fall Scholars Week 2025
Honors College Senior Thesis Presentations
Effect of Freezing and Freeze-thaw Cycles on Equine Serum Insulin Concentration: A Pilot Study
Insulin dysregulation is a key component of Equine Metabolic Syndrome (EMS), and is a precursor to other maladies like laminitis and liver failure. Diagnosis of EMS is conducted through blood sampling measuring the concentration of insulin and glucose in the blood. Achieving an accurate result of insulin concentration is vital for diagnosis, making proper sample handling essential. The aim of this project was to evaluate the effect of repetitive freeze-thaw cycles on equine serum insulin concentrations. Serum was collected from 10 university-owned horses and split into four treatment groups: Unfrozen, Once Frozen, Twice Frozen, and Three Times Frozen. Unfrozen serum was sent immediately for analysis and the other samples were maintained in a regular freezer (0 ℉, -18 ℃) for the freeze-thaw process. Once the freeze-thaw process was complete, all frozen samples were sent to the laboratory for radioimmunoassay analysis. Data were analyzed using the MIXED procedure of SAS. The concentration data were analyzed for main effects of sex, age, and freeze-thaw cycle. There was an effect of age on serum insulin concentration (P < 0.0001). Older horses had higher concentrations than younger (28.7458 ± 1.7998 uIU/mL and 51.6967 ± 2.3236 uIU/mL, respectively), which was in agreement with other published results. There was no effect of freeze-thaw cycles, which was similar to previously reported studies in other species. There was also no effect of sex, which was not in agreement with previous reports where mares were reported to have higher serum insulin concentrations than geldings. The results of this study will equip veterinarians and laboratories to freeze equine insulin serum samples up to three times and still be confident of an accurate result.