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Q&A With Leader In Equine Anesthesia

Dr. John Hubbell is considered one of the most experienced equine anesthesiologists in the industry. Currently the chief of anesthesia at Rood and Riddle Equine Hospital in Lexington, Ky., Hubbell was interviewed by The Horse to learn more about equine sedation and anesthesia.

Hubbell told The Horse that the sedatives in use today include xylazine, acepromazine, detomidine, romifidine, and butorphanol, which were developed between the 1970s and 1990s. Prior to the introduction of these drugs, physical restraints were often used in many medical procedures.

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Hubbell reported that the sedatives used today take effect within three to five minutes. Adult horses often remain standing, even when heavily sedated.

With today's lessened reliance on physical restraints, the safety of the horse and the people surrounding him is heightened.

Though anesthesia is the safest it's ever been, there are still risks associated with laying the horse down on its side. Horses that are older (over 17 to 20 years old), those that are large, and those that aren't used to being handled are at the greatest risk of anesthesia complications. Horses in the last two categories, especially, can be difficult to help stand after anesthesia.

Hubbell said procedures that use short-term anesthesia, where the horse is recumbent for 20 to 30 minutes, do not present as many potential issues as procedures which require horses to be under anesthesia for more than 90 minutes.

There are no breed-specific dosing protocols, but Hubbell has found that American Saddlebreds and draft horses often need smaller doses of detomidine or xylazine as compared to Appaloosas, Arabians and Mustangs.

Hubbell has also found that the atmosphere in which he's performing the procedure will affect how much sedation is required. He noted that horses which have been handled regularly and that are taught to behave often require smaller doses of sedative.

How Sedated Is My Horse? Research Provides A Scale To Help Non-Veterinarians

A practical tool to help assess the depth of equine sedation has been developed. The facial sedation scale, called FaceSed, is based on the Horse Grimace Scale, which uses equine facial expressions to assesses pain.

Dr. Alice Rodrigues de Oliveira and other scientists at São Paulo State University in Brazil noted that there was only one objective measure of sedation in horses that didn't require interpretation: head height above the ground. Other methods being used to assess depth and quality of sedation were subjective and based on the observer's experience with sedated horses.

Though there are typical facial responses to sedation, no studies have measured their validity and reliability. The research team sought to create a scale that measured equine sedation based on facial expression. They adapted three of the facial measures used in the Horse Grimace Scale: ear position, eye opening, and relaxation of the lower and upper lips.

To test their pain scale, the scientists sedated seven horses both lightly and heavily, and photographed the horse's face before sedation, at the height of sedation, in the middle, and at the end of sedation. Images were sent to four vets who were trained on the FaceSed scale.

There was agreement and consistency between all four vets. The scientists determined that the FaceSed scale is a reliable tool to assess and determine sedation in horses. They recommend further studies be completed in clinical settings and using inexperienced observers.

Read the article here.

Study: Sedation And Whip Use May Lead To Trailering Trouble

Trouble getting a horse on a trailer is common; it often takes time and patience to get a horse to the point where he will load and travel well. However, if the horse needs to get on a trailer and there isn't multiple hours or days to work with him, there are quite a few tricks horse handlers can use, employing everything from feed to brooms to whips to sedation to get him in the trailer.

Nearly 14.5 percent of responders to an Italian study indicated that they had issues loading horses in their care onto trailers within the last two years. The 37-question, online survey was sent to people who were directly involved with the transportation of horses, either for recreational or professional purposes. The survey aimed to identify risk factors for problem behaviors and injuries.

The study team, made up of Drs. Francesca Dai, Martina Zappaterra, Michela Minero, Francesca Bocchini, Christopher Riley and Barbara Padalino, received 148 responses. The questions they asked related to the handler's equine background, vehicles, practices and experience. They were also asked if horses they handled sustained transport injuries within the last two years.

The most common problem behaviors were related to fear and anxiety before loading, including kicking and refusing to get on the trailer, and loss of balance while in the trailer. They discovered that the probability of the horse displaying an issue were:

three times more likely if the driver didn't check the brakes before hauling
five times more likely if the handler was female
five times more likely if the horse handler used a whip at loading
five times more likely if the vehicle wasn't designed for horse protection and if the trailer didn't have shavings as bedding
13 times more likely if the animal was sedated,

Nearly 11.5 percent of respondents said that their horses had injuries directly related to transportation within the last two years. The researchers determined that sedation and coercive equipment, like using whips, were major risk factors for injuries. Though sedation may be helpful to get a horse on a trailer, it can affect the ability of a horse to balance once the trailer is in motion.

Horses were more likely to be injured during travel if the trailer brakes weren't checked before transport, there was no padding on the chest bar and if there were no rubber mats on the floor. Horses that exhibited problem behaviors during loading and transport were more likely to be injured.

The study team concluded that transportation is a risk to the wellbeing of both the horse and the handler, and suggested that more research is needed.

Read the full study here.

AAEP Convention: Standing Arthroscopy Can Be Used On More Than Stifles

When traditional diagnostic tools such as X-ray and ultrasound provide no definitive diagnosis for an equine lameness, a vet may perform an arthroscopy. While this procedure typically requires putting the horse under general anesthesia, a needle arthroscopy can be done while the horse is under standing sedation, Dr. Alvaro Bonilla said at the virtual 2020 American Association of Equine Practitioners Convention and Trade Show.

A safe, reliable procedure, needle arthroscopy is less risky and less costly to the owner; putting a horse under general anesthesia for surgery has its own risks, including recovery. While typically used for diagnostics, a standing arthroscopy can also be used therapeutically for septic joints and small osteochondral fragments, specifically for dorsal fragments of the first phalanx in the fetlock, Alvaro says. However, the procedure does still have limitations.

Previously, needle arthroscopy was used only in the stifle joint; Alvaro reports that now it can be used successfully to evaluate multiple synovial structures, including shoulders, fetlocks, hocks, radiocarpal and middle carpal joints, and carpal sheaths.

When using this diagnostic tool, it's important that the horse is sedated, but not overly so, which could make him unsteady and make the procedure not only difficult, but dangerous. Additionally, the surgical site must be sterile, which can be difficult as debris can fall onto the joint or the horse can urinate. Potential for both complications can be decreased by using blankets and inserting a urinary catheter.

An adjustable, lightweight splint made from stainless steel and aluminum is used during the procedure; to ensure as successful an outcome as possible, horses should be acclimated to wearing the brace before being sedated for the surgery.

The surgical area should be bandaged for four to five days following the procedure; horses that had the procedure for diagnostic reasons can go back to work as soon as the bandages are removed.