Effects of omeprazole therapy administered via different routes on urinary parameters and selected interleukins in horses with equine gastric ulcer syndrome.

Overview

• This study investigated the effects of oral versus injectable omeprazole treatment on kidney-related urinary markers and interleukin levels in horses with equine gastric ulcer syndrome (EGUS), focusing on potential subclinical kidney injury.

Background

• Equine gastric ulcer syndrome (EGUS) is a common condition in horses characterized by gastric ulcers.
• It is typically treated with proton pump inhibitors (PPIs) such as omeprazole, which reduce stomach acid.
• Omeprazole can be administered orally or by injection in horses.
• In humans, omeprazole use has been linked to acute interstitial nephritis (AIN), a type of kidney injury, possibly through oxidative stress mechanisms.
• Urinary interleukins (immune signaling molecules) have potential as early, non-invasive biomarkers for detecting kidney injury in humans.
• However, it was unclear if such kidney risks or urinary markers were relevant in horses treated with omeprazole.

Objective

• To assess whether oral or injectable omeprazole treatments lead to changes in basic urinary parameters or levels of selected interleukins (IL-9, IL-18) and tumor necrosis factor alpha (TNF-α) in horses with EGUS.
• To specifically explore if there is evidence of subclinical acute interstitial nephritis (AIN) reflected in these urinary markers after omeprazole treatment.

Methods

• Study Design: Prospective cohort study involving 16 horses diagnosed with EGUS.
• Treatment Groups: Horses were treated for 28 days with either oral or injectable omeprazole at 4 mg/kg dosage.
• Sampling Times: Urine samples collected at diagnosis (before treatment, T0) and after completing treatment (T1).
• Parameters Measured:
  • Basic urine physicochemical parameters (e.g., sodium concentration, gamma-glutamyl transferase (GGT) values).
  • Urinary levels of interleukins IL-9, IL-18, and TNF-α, which can indicate immune response or kidney inflammation.

Results

• None of the horses developed clinical signs of kidney injury during or after treatment.
• IL-9 and TNF-α were undetectable in all urine samples, suggesting no immune activation related to these cytokines.
• Urinary IL-18 levels showed no significant change at the group level between pre- and post-treatment samples.
• On an individual basis:
  • 9 out of 16 horses had increased IL-18 at T1 compared to T0.
  • 7 out of 16 horses showed increased urinary GGT values at T1.
• Urinary sodium concentration significantly increased only in the oral omeprazole treatment group (p = 0.046), indicating possible mild alterations in renal sodium handling.

Conclusions

• The study found no evidence linking omeprazole administration—either oral or injectable—to changes in urinary cytokines that would suggest subclinical acute interstitial nephritis in horses.
• No clinical or biochemical signs of acute kidney injury were detected in treated horses.
• The increase in urinary sodium only in oral treatment and individual variability in IL-18 and GGT warrant cautious interpretation.
• Due to the small sample size, results should be confirmed by larger-scale studies before ruling out risk entirely.
• Overall, omeprazole appears safe regarding kidney injury biomarkers in horses for the dose and duration tested.