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Measurement of 24-h gastric pH using an indwelling pH electrode in horses unfed, fed and treated with ranitidine.
Abstract: A glass combined pH-reference electrode was placed in the stomachs of 5 adult horses and pH was recorded every 6 mins for 24 h while (1) feed and all bedding materials were withheld for 24 h (unfed), (2) horses had free access to Timothy grass hay for 24 h (fed), and (3) horses had free access to Timothy grass hay and were treated with ranitidine, 6.6 mg/kg body weight, orally, every 8 h for 48 h (fed + ranitidine). There was a significant (P = 0.007) difference in median 24-h gastric pH amongst the 3 protocols, the value being 3.1 in fed horses and 1.55 in unfed horses (P = 0.05) and 4.6 in fed + ranitidine horses (P = 0.05 compared with fed horses). The percentage of pH readings 2.0, 3.0, 4.0, 5.0 and 6.0 were each significantly (P = 0.05) greater in fed + ranitidine horses than in fed horses, and in fed than in unfed horses. There was no difference (P = 0.13) between median gastric pH values from different times of day in unfed horses (00:00 to 06:00 h, 1.5; 06:00 to 12:00 h, 1.6; 12:00 to 18:00 h, 1.7; and 18:00 to 24:00 h, 1.5). We conclude that gastric acidity is greatest when horses do not have access to feed material and that ranitidine effectively suppresses gastric acidity in horses under conditions of free access to hay.
Publication Date: 1993-09-01 PubMed ID: 8223373DOI: 10.1111/j.2042-3306.1993.tb02983.xGoogle Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
This study investigates the effect of feeding and ranitidine treatment on the stomach pH levels in horses. It found that stomach acidity is highest when horses do not have access to feed, and use of the drug ranitidine can significantly reduce this acidity when horses have free access to hay.
Research Methodology
- The researchers placed a glass combined pH-reference electrode in the stomachs of 5 adult horses to measure their stomach acidity, recording the pH every 6 minutes over a 24-hour period.
- Three conditions were tested on the horses: (1) horses were left unfed and had no access to bedding materials for 24 hours; (2) horses were given free access to Timothy grass hay for 24 hours; and (3) horses were given free access to Timothy grass hay and treated with 6.6 mg/kg body weight of ranitidine orally every 8 hours for 48 hours.
Findings
- Significant differences (P = 0.007) were found in the median 24-hour gastric pH under the three tested conditions. The median gastric pH was 3.1 for fed horses, 1.55 for unfed horses (P = 0.05 compared with fed horses), and 4.6 for horses fed with ranitidine (P = 0.05 compared with fed horses).
- The percentage of pH readings less than 2.0 was significantly higher in unfed horses (76%) compared to fed horses (30%) and in fed horses compared to those fed with ranitidine (9%).
- Percentage of readings higher than 2.0, 3.0, 4.0, 5.0 and 6.0 were significantly greater in horses fed with ranitidine compared to fed horses and in fed horses compared to unfed horses.
- No significant variations were found in the median gastric pH values at different times of the day for unfed horses.
Conclusion
- The study concludes that horses exhibit the greatest stomach acidity when they do not have access to feed.
- The administration of ranitidine is effective at reducing gastric acidity in horses that have unrestricted access to hay, emphasizing its potential use for managing equine gastric issues.
Cite This Article
APA
Murray MJ, Schusser GF.
(1993).
Measurement of 24-h gastric pH using an indwelling pH electrode in horses unfed, fed and treated with ranitidine.
Equine Vet J, 25(5), 417-421.
https://doi.org/10.1111/j.2042-3306.1993.tb02983.x Publication
Researcher Affiliations
- Marion duPont Scott Equine Medical Center, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Leesburg 22075.
MeSH Terms
- Animals
- Eating / physiology
- Electrodes / veterinary
- Female
- Food Deprivation / physiology
- Gastric Acidity Determination / veterinary
- Gastroscopy / veterinary
- Horses / metabolism
- Hydrogen-Ion Concentration
- Intubation, Gastrointestinal / veterinary
- Male
- Ranitidine / pharmacology
- Stomach / chemistry
- Stomach / drug effects
Citations
This article has been cited 12 times.- Song Y, Day CM, Afinjuomo F, Tan JE, Page SW, Garg S. Advanced Strategies of Drug Delivery via Oral, Topical, and Parenteral Administration Routes: Where Do Equine Medications Stand?. Pharmaceutics 2023 Jan 4;15(1).
- Albanese V, Munsterman A, Klohnen A. Prevalence of Gastric Ulceration in Horses with Enterolithiasis Compared with Horses with Simple Large Intestinal Obstruction. Vet Sci 2022 Oct 25;9(11).
- Sykes BW, Hewetson M, Hepburn RJ, Luthersson N, Tamzali Y. European College of Equine Internal Medicine Consensus Statement--Equine Gastric Ulcer Syndrome in Adult Horses. J Vet Intern Med 2015 Sep-Oct;29(5):1288-99.
- Woodward MC, Huff NK, Garza F Jr, Keowen ML, Kearney MT, Andrews FM. Effect of pectin, lecithin, and antacid feed supplements (Egusin®) on gastric ulcer scores, gastric fluid pH and blood gas values in horses. BMC Vet Res 2014;10 Suppl 1(Suppl 1):S4.
- Birkmann K, Junge HK, Maischberger E, Wehrli Eser M, Schwarzwald CC. Efficacy of omeprazole powder paste or enteric-coated formulation in healing of gastric ulcers in horses. J Vet Intern Med 2014 May-Jun;28(3):925-33.
- Perkins GA, den Bakker HC, Burton AJ, Erb HN, McDonough SP, McDonough PL, Parker J, Rosenthal RL, Wiedmann M, Dowd SE, Simpson KW. Equine stomachs harbor an abundant and diverse mucosal microbiota. Appl Environ Microbiol 2012 Apr;78(8):2522-32.
- Broome TA, Brown MP, Gronwall RR, Casey MF, Meritt KA. Pharmacokinetics and plasma concentrations of acetylsalicylic acid after intravenous, rectal, and intragastric administration to horses. Can J Vet Res 2003 Oct;67(4):297-302.
- Murray MJ. Equine model of inducing ulceration in alimentary squamous epithelial mucosa. Dig Dis Sci 1994 Dec;39(12):2530-5.
- Brauns M, Ali A, Berger J, McLean A. Physiological and Behavioral Responses of Stabled Horses (Equus caballus) to Three Types of Environmental Enrichment. Animals (Basel) 2025 Sep 23;15(19).
- Irving J, Pineau V, Shultz S, Ter Woort F, Julien F, Lambey S, van Erck-Westergren E. Impact of Low-Starch Dietary Modifications on Faecal Microbiota Composition and Gastric Disease Scores in Performance Horses. Animals (Basel) 2025 Jun 28;15(13).
- Hodgson E, Thirouin M, Narayanan P, Romano TR, Wise J, Bond S. A novel placement method of a calibration-free pH capsule for continuous wireless measurement of intragastric pH in horses. J Vet Intern Med 2025 Jan-Feb;39(1):e17273.
- Guerrero JLS, Brito PHS, Ferreira MA, Arantes JA, Rusch E, Oliveira BVDS, Velasco-Bolaños J, Carregaro AB, Dória RGS. Evaluation of Gastric pH and Gastrin Concentrations in Horses Subjected to General Inhalation Anesthesia in Dorsal Recumbency. Animals (Basel) 2024 Apr 15;14(8).
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