anesthesia | Horse Racing Free Tips

Standing Surgery A Non-Traditional Option For Severe Colic Cases

Colic is a very real concern to horse owners. An overarching term applied to any abdominal pain, over 80 percent of colic cases can be resolved without surgical intervention.

The standard colic surgery needed for horses which do require medical intervention involves putting the horse under general anesthesia, laying him down and opening the horse along his ventral midline. This type of surgery carries additional risk to the horse and adds significantly to the cost of treatment.

A new study has found that a flank incision, made while the horse is standing, may be a good option for specific types of colic. This type of surgery is less risky to the horse and less of a financial strain for the owner.

Dr. Marco Lopes and a study team reviewed records of 26 horses and ponies and one donkey which underwent a standing flank laparotomy between 2003 and 2020. The main reason for the decision to utilize this particular surgery was financial.

Though seven animals were euthanized due to an untreatable condition or a poor chance of survival, 20 of the 30 horses with treatable conditions survived. The surviving horses suffered from small intestine impaction or inflammation, large colon displacement (specifically nephrosplenic ligament entrapment), and sand impaction.

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Small colon impaction has already been found to respond well to the standing-flank incision method of treatment.

Study authors found that there are limitations to the surgery. These include:

The horse must remain still during the operation; one in intense pain from severe colic may not be able to have his pain controlled well enough to complete the surgery
Peritoneal cavity and abdominal organ access is not as good as with a typical ventral midline incision
A second incision on the opposite flank may be necessary

The team concluded that a standing flank laparotomy may be a viable approach for abdominopelvic exploration in horses with colic related to the small intestine, cecum, large colon, and peritoneum.

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.

Let Them Eat: Horses Undergoing Non-Abdominal Surgery May Be Better Off Eating

Much like human doctors, veterinarians often recommended that horses slated for surgery fast before undergoing anesthesia. In humans, this reduces the risk of the development of aspiration pneumonia; in horses it was thought to decrease the risk of post-operative colic. However, a study has shown that there may be no need for horses scheduled for non-abdominal surgery to refrain from eating.

A retrospective study over a two-year period used 1,965 horses older than two years old that were referred to the Oakridge Equine Hospital in Edmond, Okla., for non-emergency, non-abdominal procedures. The horses had not fasted prior to their surgeries.

Dr. Patricia Baily and her study team found that only 2.5 percent of the horses that had not been fasted became colicky. They also found no correlation between the age of the horse, the surgery performed or the duration of the anesthesia and colic risk.

The scientists conclude that allowing a horse to eat prior to undergoing general anesthesia for a non-abdominal surgery doesn't increase his colic risk. In fact, allowing the horse to eat may help him maintain gut motility, reducing the risk of post-operative colic.