Does Phenylbutazone Administration Contribute to Gastric Permeability and Ulceration in Horses?

Abstract

IntroductionGastric ulcers are commonly found in equine athletes and there is evidence suggesting phenylbutazone may increase the incidence. In human athletes, gastric permeability has been shown to increase with non‐steroidal anti‐inflammatory use with potential to negatively affect performance and recovery. The aim of this study was to examine the effects of phenylbutazone on gastric mucosa and permeability.Methods18 Arabian horses were examined via gastroscopy on day 0, 42, 49, 56, and 63, with ulceration in both the squamous and glandular regions scored from 0 to 4. For seven days commencing after the day 42 evaluation, horses received 4.4 mg/kg BW phenylbutazone twice daily PO. On day 49, sucrose (1 g/kg bwt) was administered via nasogastric tube, with blood and urine samples collected for 90 min and 4 h, respectively, to assess gastric permeability. Data were analyzed using SAS 9.2 with Proc MIXED.ResultsUlcer scores increased from day 42 to day 49 (P<0.0001) with prevalence of grade 2 or greater ulceration being 33% on day 42 compared with 94% on day 49. Scores decreased from day 49 to 56 and, though continuing to decrease, had not returned to baseline scores by day 63. Squamous scores increased from day 0 to day 49 and remained elevated through day 63, while glandular scores were highest on day 49 but had decreased by day 56 (P<0.05). Sucrose concentration increased (P<0.0001) in both plasma and urine after phenylbutazone administration.ConclusionsBesides exacerbating gastric ulcers, phenylbutazone contributes to gastric permeability and, particularly when combined with strenuous exercise, may impair recovery and increase illness susceptibility.Ethical Animal ResearchAll methods were approved by the Michigan State University Institutional Animal Care and Use Committee (approval number 10/11‐216‐00). Sources of funding: Zinpro Corporation. Competing interests: none.