It’s likely that at some point during a horse’s life, he will need to be sedated, either for a routine procedure like a dental float or sheath cleaning, or possibly for a serious health issue that requires the horse to remain still to receive veterinary care. Equine sedation works along the same pathways sedation does in humans: by disrupting communication in the nervous system and slowing down brain activity. The administration of sedatives alters the horse’s level of consciousness and his ability to perceive what is happening to him and around him. A sedated horse will be quiet and should react minimally to stimuli, which is critical for keeping him, the veterinarian and others around him safe.
Standing sedation is the type most often used on the farm for calming a horse while keeping him upright.
“Basically, we’re taking the edge off,” says Magdalena Niedermeyer, DVM, of Burnt Fork Veterinary Clinic in Stevensville, Mont. “The horse is still standing, but he seems drunk. Sedation is not anesthesia, so if a horse really doesn’t like something, he can still tell you while sedated.”
Horses are often given a mixture of drugs instead of just one to ensure they are not a threat to themselves or those around them during the procedure. The type and amount of each drug used will depend on the horse’s size, state of mind at time of sedation, and how long the horse will need to remain sedated. Horses that are more anxious at the time of delivery may require more drugs than a horse that is calm.
How Equine Sedation is Administered
There are multiple ways to sedate a horse, but the bottom line is that the more quickly the drug gets into the horse’s bloodstream, the more rapidly he will become sedated.
Often the drug and administration route are chosen by a veterinarian; vets will often discourage horse owners from administering injectable sedation on their own. While this is because a good portion of horse owners don’t know how to administer drugs properly, it’s also related to the type of drugs being used.
Be aware that many drugs that sedate horses are powerful, and if inadvertently given outside of the vein or into an artery, they could have harmful effects. Additionally, if human contact occurs, some drugs could impose serious health risks, including death.
Sedation can be administered in the following ways, from most rapid to least rapid.
Intravenously (IV)
- Effects within minutes.
“IV sedation is the quickest sedation used by veterinarians for procedures such as joint injections, dental examinations, minor surgeries, and other standing procedures, in addition to emergency situations or colic,” says Holly Helbig, DVM, Equine Technical Services Veterinarian with Zoetis.
Intramuscularly (IM)
- Effects within 5 to 15 minutes.
IM sedation goes directly into the muscle and does not require the administrator to locate and administer through a vein.
Sublingual (under the tongue)
- Effects within 40 minutes.
“Sublingual administration requires the medication be placed under the tongue so it can be absorbed through the oral mucous membranes, directly into the bloodstream,” explains Helbig. “It is very effective because it bypasses the digestive system.”
Oral
- Effects within 40 minutes.
“When medication is labeled to be given orally, it’s designed to be placed in the back of the mouth and swallowed, like a deworming paste,” says Helbig. “It is then absorbed through the gastrointestinal tract and into the bloodstream.”
Dormosedan GelDormosedan® is a safe and effective sedative for horse owners that is delivered sublingually (under the tongue). As this gel requires no injection, many horse owners and handlers are comfortable administering it. However, owners should expect to have their horse examined by a veterinarian prior to dispensing Dorm gel (or administering injectable drugs); the vet wants to be able to rule out signs of illness like fever or cardiac issues that could cause side effects, says Magdalena Niedermeyer, DVM, of Burnt Fork Veterinary Clinic in Stevensville, Mont. Available in single-dose syringes, owners need not be concerned about having too much product on hand that might expire. This sedative takes a minimum of 40 minutes to work, and results last from 90 to 190 minutes. Disposable gloves should be worn during administration, as it can absorb through human skin. Hands should be washed immediately following administration, especially if any gel is seen on the skin. IMPORTANT SAFETY INFORMATION: Do not use DORMOSEDAN® GEL in horses with pre-existing atrioventricular (AV) or sinoatrial (SA) block, with severe coronary insufficiency, cerebrovascular disease, respiratory disease, or chronic renal failure. Do not use in anesthetized or sedated horses, or in conditions of shock, severe debilitation or stress due to extreme heat, cold, fatigue or high altitude. Do not use in horses intended for human consumption. Handle gel-dosing syringes with caution to avoid direct exposure to skin, eyes or mouth. See full prescribing information at DormGel.com/PI. |
It’s important care still be taken when handling a sedated horse, no matter how the drugs were administered. A sedated horse is conscious, meaning he can still react to sound and movement.
It’s critical that everyone around the horse pay close attention and not be lulled into a false sense of security that he will ignore most things going on around him. Loud noises, like the banging of feed bins or clanging of stall doors, could elicit a forceful reaction, and possibly endanger those around the horse.
How Do Horses Act Under Sedation?
A sedated horse is easy to spot: He will often stand with his legs splayed out, looking like he’s trying to catch his balance. His head will droop, sometimes to the floor.
“Typically, when the poll [drops] below the level of the withers is when the horse is in the correct plane of sedation for work to be performed,” says Helbig. “While the horse is settling into sedation, he may abruptly ‘catch’ himself with a leg, or buckle or cross his legs (ataxia and incoordination). This is normal—don’t try to hold up the horse or wake him by patting his head or neck.” This will delay the onset of action and prevent the horse from achieving the maximum plane of sedation.
“Depending on the environment [including heat, humidity, sun or shade], the horse may also sweat over his neck, shoulder, flanks or around the ears. This is also normal and transient,” says Helbig.
Though it’s not entirely clear why a horse may sweat from sedation, it’s not a cause for concern, she says.
“It is believed that the sedation stimulates the sympathetic nervous system, causing an inability to thermoregulate. Vasoconstriction caused by these drugs also increases body temperature, [and] that triggers sweating.”
If asked to walk, the horse often looks like he’s drunk, moving his legs in an uncoordinated manner, unable to walk in a straight line. Though this can be disconcerting to see, a horse rarely falls, even while holding still.
“Even if they are unsteady, they can usually reposition and correct their balance themselves,” says Niedermeyer.
Helbig agrees.
“The same passive-stay apparatus that allows horses to sleep standing up allows us to sedate horses and keep them on their feet,” she says. “The apparatus has three main components: Patellar locking, the reciprocal mechanism, and the check apparatus, which are an arrangement of muscles, tendons and ligaments that, when activated, allow the horse to lock their limbs standing with virtually no muscular effort.”
How Long Does Equine Sedation Last?
“The duration of effect [of sedation] varies by the type of sedation and route of administration,” explains Helbig. “It can range from 20 minutes to a couple of hours. Some types of sedation are fast-acting and metabolized quickly, while sedation given IM or orally will have a much slower onset than medications given IV. A higher dose of sedation will likely result in a deeper level of sedation and a longer time the horse will be sedated. Your veterinarian will be able to give you an approximate amount of time for this to occur based on the type of sedation used and the dose.”
Sedated horses can be unstable. Typically after a procedure, two people (one at the head and one at the tail as an anchor) help safely guide the horse back to a clean, quiet stall to wake up, says Helbig. If a stall is not available, being alone in a ring or flat paddock is also acceptable.
The horse should not be offered hay, grain or water as he recovers; his muscles are still relaxed from the sedative, putting him at risk of aspiration or choke.
A horse coming out of sedation will begin moving his ears, chewing and licking his lips, and begin looking for food as the sedation begins to wear off, says Helbig. He will often urinate as well.
“There isn’t much owners can do for the horse [coming out of sedation] besides allow time for the medication to be metabolized, so it’s best to leave him alone until you see him starting to look around and interacting with his environment,” she says.
Keeping a Sedated Horse SafeDo:
Don’t:
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Key Takeaway
Equine sedation is crucial to various forms of veterinary care. Multiple methods of sedation are available to horses, and the type of administration—as well as the amount of medication used—varies based on procedure and the horse itself. The sedation process for horses is quite similar to the process in humans, though of course, we are dealing with a much larger animal which requires careful administration and precautions.
This article about equine sedation appeared in the October 2023 issue of Horse Illustrated magazine. Click here to subscribe!
