Investigation of Serum Triglyceride (fat metabolite) in Newborn Foals (13-06)

Investigators

K. Gary Magdesian, DVM, Dipl. ACVIM, ACVECC, ACVCP

Emily H. Berryhill, DVM

Judy Edman, BS.

Brief Background of the Problem:There are multiple anecdotal reports of newborn foals transiently having blood samples that appear to have a high fat content.  However, there is little scientific information available to substantiate these observations, their basis, and their significance to the health of the foal.  While increased serum triglycerides in adult horses reflect metabolic derangements due to illness and a negative energy balance, foals have a different body composition and metabolism than adults, and thus may release triglycerides into the serum postprandially. 

Hypothesis Statement: Newborn foals will have higher and more variable serum triglyceride concentrations compared to reported values for adult horses with transient lipemia (fatty blood) occurring as a normal phenomenon .  A secondary hypothesis is that serum triglyceride concentrations and patterns of release over time will differ between foals <48 hours of age and foals between 10-12 days of age.  A final hypothesis is that triglyceride concentrations in healthy foals will differ from those of sick foals of similar ages. 

Specific Objective(s) of the Study:

1.  To determine the triglyceride concentrations and their variation in the bloodstream over time in newborn foals.  

2.  To compare serum triglyceride concentrations and their patterns over time between healthy foals <48 hours old and foals between 10-12 days old.

3.  To compare serum triglyceride concentrations from healthy foals to those of hospitalized sick foals based on medical records. 

Overview of Experimental Approach:

Seven foals will have a blood sample collected immediately after birth (pre-suckle) and one hour post nursing.  Serial blood samples will be taken from the same foals again on day 2 of life and again 10 days later (for a 12 h period).  A blood sample will also be taken from the dams concurrently. After triglyceride analysis, results will be compared to data obtained from the medical records of sick foals. 

Anticipated Benefits to the Equine Industry: The value of serum triglyceride concentrations as an equine diagnostic is becoming well known.  They increase with sepsis, the leading cause of death in foals, and liver disease. However, healthy foals are noted to have fatty blood, and this is poorly understood and never documented. Establishing an understanding of triglyceride concentrations in newborn foals, how concentrations change over the course of the first several hours and days of life, and how they compare to sick foals will provide further insight into normal foal physiology and aid in assessment and treatment of sick foals. 

Accomplishments/Results (in "bullet" form)

  • An age-dependent effect on serum triglyceride (TG) concentration was established.
    • Foals <24 hours old had serum TG concentrations similar to those of the mares (median 28 mg/dl for foals, 20 mg/dl for mares).
    • Foals 24-48 hours old had significantly higher serum TG concentrations as compared to the older foals and adult mares (median 89 mg/dl).
    • Foals 10-12 days old had significantly higher serum TGs than the mares, but significantly lower serum TGs than the 24-48 hour foals (median 60 mg/dl).
  • For the 24-48h sampling period, serum TG concentrations at T=0 through T=5 hours were significantly different (less than) T=16 h, indicating that triglyceride concentrations in newborns can fluctuate within the same day.
  • For the 10-12d sampling period, serum TG concentrations at T=0, T=2, T=3 hours were significantly lower than at T=12 h, also demonstrating that TG concentrations can fluctuate widely in foals up to 2 weeks of age.
  • When TG concentrations from each age group were compared against one another, significant differences were found: there was a significant difference between the two groups as time progressed from T=0 through T=16 (P=0.003),  a significant difference between the young age versus the older age (p=0.036), and a significant difference overall when both the effect of foal age and time interactions were taken into account (p=0.0017).
  • Mares had significantly higher serum TG concentrations at parturition compared to 24-48h and 10-12 days after parturition.  
  • Sick foals had higher serum triglyceride concentrations compared to healthy foals, with significant differences found in foals between 8-12 days of age (108mg/dl vs. 60mg/dl; p<0.0037).
  • Nonsurviving sick foals had higher serum triglyceride concentrations than surviving sick foals (116mg/dl vs. 65mg/dl; p<0.0425).
  • Summary of findings: the hypothesis that young neonatal foals would have higher serum TG concentrations than older foals and adult horses was found to be true. Serum TG concentrations were affected by foal age, sampling time, and an interaction between the two. Sick foals had higher serum triglycerides than their healthy counterparts, and higher triglyceride concentrations were associated with nonsurvival. 
  • Further study analyzing serum insulin and glucose concentrations utilizing the same foal serum samples is being planned. 

Benefits to the Equine Industry (2 or 3 sentences)

The results of this study provide normal ranges for serum triglyceride concentrations for newborn and 10-12 day old foals, as well  as for the immediate post-partum mare.  The values are higher than that reported for adult, non-lactating mares.  In addition, comparisons in triglyceride concentrations between age-matched healthy and sick foals are provided. This information provides critical baseline values necessary for evaluating triglyceride concentrations in sick foals and post-partum mares in the clinical setting. Examples would include foals with sepsis and mares with Equine Metabolic Syndrome. The results  allow veterinarians to make correct decisions regarding hyperlipidemia in sick patients, based on their age or signalment.