The effect of adrenergic suppression induced by guanabenz administration on exercising Thoroughbred horses

Colahan, Patrick T.; Savage, Katy; Tebbett, Ian R.; Rice, Brett L.; Jackson, Christie A.; Freshwater, Les

doi:10.1111/j.2042-3306.2006.tb05550.x

Cited by 3 publications

(3 citation statements)

References 8 publications

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“…Guanabenz at 0.2 mg/kg exceeded the head droop effect of the highest amitraz dosage by about 90 min (to 240 min), although this could be rapidly reversed by yohimbine administration within about 10 min. The findings of strong sedation are consistent with those reported by Colahan et al (1996) who also found decreased heart rate in exercising Thoroughbreds treated with 0.08 mg/kg guanabenz.…”

Section: Sedationsupporting

confidence: 91%

“…Guanabenz is closer to clonidine in its alpha-2/alpha-1 affinity (Maze and Tranquilli 1991). Owing to its sedative and analgesic properties, guanabenz has gained significant interest among horse owners as a calming agent (Colahan et al 1996), whether injected by a veterinarian for therapeutic purposes or by owners or trainers desiring increased horse control. Interest in guanabenz exists since most of the behavior-altering drugs used today in the horse industry originated from harsher psychotropic drugs used to treat human mental illness, such as antipsychotic drugs acepromazine, chlorpromazine, fluphenazine and reserpine (Tobin 1981).…”

Section: Introductionmentioning

confidence: 99%

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Guanabenz in the horse – A preliminary report on clinical effects and comparison to clonidine and other alpha-2 adrenergic agonists

Lehner¹,

Dirikolu²,

Tobin³

2022

PHK

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In veterinary medicine, a number of alpha-2 receptor agonists are marketed as sedatives/hypnotics and analgesics, with their principal use being the chemical restraint of large and small animals. Guanabenz (Wytensin ® ) is an alpha-2 adrenergic receptor agonist marketed for use in humans as an anti-hypertensive agent. Recent reports indicate that guanabenz has been administered to horses in small doses (0.04 mg/kg) for its anti-hypertensive effects. While this offers both benefits of sedation of the horse as well as amelioration of pulmonary hypertension during running exercise and consequent Exercise-Induced Pulmonary Hemorrhage (EIPH), guanabenz is currently proscribed in most racing jurisdictions and its administration to a racing horse can lead to penalties. The Association of Racing Commissioners International (ARCI) lists guanabenz as an ARCI Class 3 agent; Class 3 agents include bronchodilators, anabolic steroids and other drugs with primary effects on the autonomic nervous system, procaine, antihistamines with sedative properties and diuretics and includes amitraz, clonidine, xylazine, detomidine, medetomidine, and romifidine. Guanabenz is unique among alpha-2 agonists in that it differentiates into E-and Z-forms (Fig. 1), with the Z-form lacking hypotensive properties, yet with both E-and Z-forms able to afford relief to cellular stresses related to inflammation or degenerative diseases. The objective of the study was a preliminary description of the pharmacological properties of guanabenz in comparison with clonidine and a number of other alpha-2 agonists. The goal was clinical evaluation of their sedative, analgesic and related activities with the goal of increasing our understanding of the clinical use of such medications and also as a possible prophylaxis for Exercise-Induced Pulmonary Hemorrhage. The clinical study of guanabenz and clonidine was performed in a complete crossover strategy using quantitative markers of sedation, antinociception, heart rate, blood and urine glucose following administration of each compound in five horses. Amitraz, detomidine, medetomidine, romifidine, and xylazine were studied in one horse each. The sedation was quantified by measuring head droop and locomotor activity, while antinociception was measured by Hoof Withdrawal Reflex Latency. Heart rates, urine glucose, urine production and urine specific gravities were also determined by standard clinical chemistry techniques. Guanabenz serum levels and related urinary guanabenz glucuronide levels were determined by established Liquid Chromatography-tandem Mass Spectrometric (LC-MS) methods. In result the clinically effective doses (0.2 mg/kg) of guanabenz produced a rapid and intense sedative effect, with sagging of the lower lip, sunken eyelids, and marked head droop corresponding to plasma guanabenz concentrations that peaked at 120 ng/mL at 2.5 min post-injection (Fig. 2). The initial head height above the ground is considered 100 %, and head heights fell to values ranging 18-40 % with guanabenz, all of which are grea...

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Section: Sedationsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Guanabenz in the horse – A preliminary report on clinical effects and comparison to clonidine and other alpha-2 adrenergic agonists

Lehner¹,

Dirikolu²,

Tobin³

2022

PHK

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“…Anecdotally two of the most commonly used agents are acepromazine and reserpine, but of particular concern is the use of a2 adrenergic agonists for the treatment of behavioural issues whilst horses are actively being ridden. Due to their analgesic and muscle relaxant properties, their effect on the cardiac and respiratory system, and the risk of heavy sedation with associated ataxiainducing effects, these agents pose a potential safety concern when used in riding horses, particularly those involved in demanding athletic pursuits (Harkins et al 2003;Colahan et al 2006;Dirikolu et al 2006;Tobin 2006;Neil 2011).…”

Section: Introductionmentioning

confidence: 99%

An online survey investigating perceived prevalence and treatment options for stereotypic behaviours in horses and undesirable behaviours associated with handling and riding

Carroll

Sykes

Mills

2020

Equine Veterinary Education

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In the horse, inappropriate management and training, as well as pain, frustration, fear and anxiety can result in undesirable behaviours. Common undesirable behaviours include pawing, striking, rearing, kicking, bolting, bucking, shying, napping, freezing, biting and bite threats, as well as a range of oral and locomotive stereotypic behaviours. Many of these behaviours are dangerous for the human handlers and can be unhealthy and harmful for the horse; for safety and welfare reasons, they must be rapidly addressed. An online survey was completed by 943 horse industry participants from 31 countries. The survey was conducted to gain greater insight into the perceived prevalence of undesirable behaviours in horses; options considered in the management of horses displaying undesirable behaviours; attitudes towards the use of prescription and over-the-counter (OTC) behaviourmodifying agents; and owner attitudes towards the role of veterinarians and equine behaviourists. The results of this survey suggest that undesirable behaviours are common. Agents with a nonspecific sedating effect were the most common agents suggested by veterinarians and used by horse-owners. Horse-owners indicated a greater use of a2 agonists for the management of undesirable behaviours associated with riding horses. Many owners in this survey indicated they would consider seeking advice from veterinarians (83.2%) and behaviourists (58.0%) if they had a horse that was 'consistently difficult or uncooperative to handle or ride'. The majority (97.3%) of nonveterinarian equine behaviourists would seek the input of a veterinarian to investigate physical causes for undesirable horse behaviour. Twenty-two percent of veterinarians would refer a case to a behaviour expert to address the behavioural component, whilst most veterinarians (77.6%) would devise a behaviour modification and retraining programme themselves. It is hoped that information from this survey can be used to improve existing horse management practices and have a positive impact on animal welfare.

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Factors affecting measurement of basal adrenocorticotropic hormone in adult domestic equids: A scoping review

Ireland,

Lester,

Banse

2024

The Veterinary Journal

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The effect of adrenergic suppression induced by guanabenz administration on exercising Thoroughbred horses

Cited by 3 publications

References 8 publications

Guanabenz in the horse – A preliminary report on clinical effects and comparison to clonidine and other alpha-2 adrenergic agonists

Guanabenz in the horse – A preliminary report on clinical effects and comparison to clonidine and other alpha-2 adrenergic agonists

An online survey investigating perceived prevalence and treatment options for stereotypic behaviours in horses and undesirable behaviours associated with handling and riding

Factors affecting measurement of basal adrenocorticotropic hormone in adult domestic equids: A scoping review

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