Research & Clinical Trials
Generous financial support from the Florida Thoroughbred Breeders and Owners Association has led to the establishment of a breeding herd at the College. Knowledge acquired from these mares and foals already is being directly applied to improving the care of equine neonatal patients. This program has reestablished UF as a leading institution in neonatology research. For example, at the convention of the American College of Veterinary Internal Medicine in Baltimore, the University of Florida contributed to 33% (6 of 18) presentations in equine neonatology. Below is a list of recent research projects completed using animals in the herd along with a description of the resultant benefits of the work.
1. Pharmacokinetics of azithromycin and clarithromycin in foals
As a result of these studies, we were able to recommend dosage regimens for azithromycin and clarithromycin in foals. We have used these drugs for the treatment of R. equi pneumonia in foals in our own hospital and have shown that clarithromycin in combination with rifampin is superior to erythromycin-rifampin or azithromycin-rifampin, especially in foals with severe pneumonia.
2. Oral antibiotics for the treatment of septicemia in foals
Cefpodoxime proxetil is an orally administered antimicrobial agent with reasonable cost, excellent antibacterial activity against a wide spectrum of bacteria and low incidence of adverse reactions. As a result of our studies, we know the appropriate oral dose for cefpodoxime proxetil in foals. We also know which common foal bacterial pathogens are susceptible to the drug so can now use an oral medication to treat foals with severe bacterial infections.
3. Omeprazole in neonatal foals
Omeprazole (GastroGard®) had previously been evaluated only in horses in horses 3 months and older. We used a disposable electrode placed through a nasogastric tube to evaluate intragastric pH in neonates and found that the drug worked quickly and effectively.
4. Assessment of two automated oscillometric monitors for indirect blood pressure measurement in neonatal foals and the effect of site of cuff placement.
Several automated indirect (using a cuff) blood pressure devices are currently available for use in humans. Sites of cuff placement that have been recommended for indirect blood pressure measurement in foals include the tail, the hind limbs just below the hock, or the forelimb midway between the carpus and the elbow. However, the effects of the type of monitor and site of cuff placement on the accuracy of indirect blood pressure measurements have never been critically investigated in neonatal foals. The objectives of this study were to assess and compare the accuracies of (Dinamap and Cardell), and to determine the optimal site of cuff placement for each monitor. We found that two automated indirect monitors commonly used for measurement of MAP in foals (Dinamap and Cardell) are accurate for the measurement of blood pressure in foals even when cardiovascular function is compromised. The tail was the best site for cuff placement. The hind limb can be used as an alternative site but cuff placement on the front limb provides inaccurate results.
5. Assessment of noninvasive cardiac output measurement by partial carbon dioxide rebreathing or two-dimensional echocardiography by comparison to the lithium dilution method in anesthetized neonatal foals.
Cardiac output is the best available parameter to assess overall cardiovascular function. Accurate measurement of cardiac output in critically ill foals would lead to a better detection and understanding of cardiovascular derangements and aid in optimal titration of therapy with intravenous fluid and with drugs affecting the cardiovascular system. Currently available techniques for monitoring cardiac output in foals require placement of a catheter in the heart or in a peripheral artery. We found that echocardiography using a simple method for calculation of cardiac output is very accurate in foals. As a direct result of this study, we are now monitoring cardiac output in critically ill foals. The ability to measure cardiac output has significantly improved our understanding of cardiovascular dysfunction in septic foals and has made selection of the most appropriate treatment easier.
6. Comparison of seven commercially available kits for the detection of failure of transfer of passive immunity in foals.
Measurement of immunoglobulin G (IgG) concentrations in neonatal foals is an important part of health assessment. We found a great variation in the accuracy of commercially available tests. Some tests were very accurate whereas others frequently resulted in misdiagnosis. The results of this study will help veterinarians and farm managers selecting the best kits for screening foals with failure of transfer of passive immunity on the farm.
7. Immunity to Rhodococcus equi infections in susceptible foals and resistant adult horses.
The reasons for the peculiar susceptibility of foals to R. equi pneumonia are unknown and the basis for immunity to R. equi in horses is poorly understood. We compared the immune response of equine neonates after infection with R. equi to that of adult horses. We found that foals develop an adult-type immune response when challenged with low-moderate numbers of bacteria but switched to a non-protective type of response when given a heavy bacterial challenge. This study is the first to identify an explanation for the peculiar susceptibility of foals to R. equi infections and may have important applications in future vaccine design.
8. Pharmacokinetics and pharmacodynamics of pantoprazole in clinically normal neonatal foals
Currently, only one proton pump inhibitor, pantoprazole, is available for intravenous use. We found that pantoprazole can be used to raise gastric pH in foals via either intravenous or oral routes. This information will hopefully provide an alternative ulcer treatment option for those foals in which oral treatment is not feasible, and will also provide appropriate dosing information for those veterinarians choosing to use this drug via the oral route.
9. Assessment of the effects of dobutamine, norepinephrine and vasopressin on cardiovascular function and tissue perfusion in anesthetized neonatal foals.
The objectives of this were to determine the individual effects of 3 commonly used drugs (dobutamine, norepinephrine and vasopressin) at various dosages on many cardiovascular parameters including blood pressure, cardiac output and gastrointestinal perfusion in foals with reduced. The information gained has been extremely valuable for the treatment of foals with hypotension and decreased cardiovascular function.