Effect of xylazine treatment on equine proximal gastrointestinal tract myoelectrical activity.
Abstract: Five 5 to 6 month old horses were surgically prepared with silver electrodes sutured to the serosa of gastric antrum, duodenum and proximal portions of the jejunum. Normal migrating motility complex (MMC) periodicity was determined during daytime hours in horses that were fed and horses from which food was withheld for 24 hours. Periodicity was defined as time span from the end of one period of regular spike activity (RSA) to the end of the next RSA in the MMC. The periodicity was 120.5 +/- 9.5 (SEM) minutes in horses from which food was withheld, and was 125.7 +/- 20.3 minutes in horses fed hay free choice. Coincident with each duodenal RSA, antral spike activity ceased. Xylazine (0.25 and 0.5 mg/kg), given IV during the period of intermittent spike activity of the MMC to either fed or unfed horses induced, within 2 minutes, a RSA complex in the duodenum that migrated to the proximal portion of the jejunum. This was followed by a period of no spike activity of normal duration, which proceeded on to a period of intermittent spike activity of varying duration to complete the MMC cycle. Pretreatment IV administration of an alpha 2-adrenergic antagonist, tolazoline (1 mg/kg) also provoked a RSA complex, but blocked the xylazine effect. The results indicated that xylazine resets the duodenal MMC in the horse, but does not seriously disrupt proximal gastrointestinal tract motility, and that control of MMC periodicity in this region probably involves more than alpha 2-adrenergic receptors.
Publication Date: 1989-06-01 PubMed ID: 2764348
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 scrutinizes the impact of xylazine, a tranquilizer, on the rhythmic muscular contractions (myoelectrical activity) in the upper digestive tracks of young horses. The research reveals that xylazine alters the movement of muscles in the horse’s stomach and small intestine, but it doesn’t disrupt the overall digestion process significantly.
Experimental Design
- Researchers used five 5 to 6-month-old horses in their study. The horses were implanted with silver electrodes that were sutured onto three key regions: the gastric antrum, the duodenum, and the proximal portions of the jejunum.
- The aim was to track the normal migrating motility complex (MMC), a measure of the cyclical muscular contractions, in these regions. Two conditions were examined: horses that were fed and horses kept hungry for 24 hours.
Results
- The results showed that MMC periodicity, the time between active muscle contraction phases, was approximately 120 minutes for unfed horses and about 126 minutes for fed horses.
- Whenever there was a spike of activity in the duodenum, activity in the gastric antrum (the last part of the stomach) ceased. This cycle is crucial because gastric antrum stops working temporarily to allow the duodenum to process food.
- Administering xylazine intravenously during periods of intermittent activity provoked an immediate response in the duodenum, which then migrated to the jejunum. This was followed by a quiet period of normal duration, and then a period of intermittent activity to finish the MMC cycle.
Findings
- The researchers tested the effect of an alpha 2-adrenergic antagonist, tolazoline. It similarly provoked a complex of regular spike activity (RSA), but it blocked the effect of xylazine.
- Researchers concluded that xylazine can reset the duodenal MMC in horses, but it does not overly disrupt the overall motility of the upper gastrointestinal tract. They proposed that the control of MMC periodicity in this region is probably more complex and involves more than just alpha 2-adrenergic receptors.
Okay, in Plain English…
- This means that while xylazine seems to be able to coordinate the movement of the muscles in the horse’s digestive track, it doesn’t disrupt it to the point of negative impact. The study helps us better understand how medications can potentially affect the digestive systems in horses.
Cite This Article
APA
Merritt AM, Campbell-Thompson ML, Lowrey S.
(1989).
Effect of xylazine treatment on equine proximal gastrointestinal tract myoelectrical activity.
Am J Vet Res, 50(6), 945-949.
Publication
Researcher Affiliations
- Department of Medical Sciences, College of Veterinary Medicine, University of Florida, Gainesville 32610.
MeSH Terms
- Animal Feed
- Animals
- Duodenum / drug effects
- Duodenum / physiology
- Eating / drug effects
- Electromyography
- Female
- Food Deprivation
- Gastrointestinal Motility / drug effects
- Horses / physiology
- Jejunum / drug effects
- Jejunum / physiology
- Male
- Pyloric Antrum / drug effects
- Pyloric Antrum / physiology
- Thiazines / pharmacology
- Xylazine / pharmacology
Citations
This article has been cited 3 times.- Verhaar N, Hoppe S, Grages AM, Hansen K, Neudeck S, Kästner S, Mazzuoli-Weber G. Dexmedetomidine Has Differential Effects on the Contractility of Equine Jejunal Smooth Muscle Layers In Vitro.. Animals (Basel) 2023 Mar 10;13(6).
- Munsterman AS, Dias Moreira AS, Marqués FJ. Evaluation of a Chinese herbal supplement on equine squamous gastric disease and gastric fluid pH in mares.. J Vet Intern Med 2019 Sep;33(5):2280-2285.
- Mitchell CF, Malone ED, Sage AM, Niksich K. Evaluation of gastrointestinal activity patterns in healthy horses using B mode and Doppler ultrasonography.. Can Vet J 2005 Feb;46(2):134-40.
Use Nutrition Calculator
Check if your horse's diet meets their nutrition requirements with our easy-to-use tool Check your horse's diet with our easy-to-use tool
Talk to a Nutritionist
Discuss your horse's feeding plan with our experts over a free phone consultation Discuss your horse's diet over a phone consultation
Submit Diet Evaluation
Get a customized feeding plan for your horse formulated by our equine nutritionists Get a custom feeding plan formulated by our nutritionists
