The Horse

MAR 2019

The Horse:Your Guide To Equine Health Care provides monthly equine health care information to horse owners, breeders, veterinarians, barn/farm managers, trainer/riding instructors, and others involved in the hands-on care of the horse.

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YOUR GUIDE TO THE 2018 AAEP CONVENTION A26 March 2019 The Horse | AAEP Wrap-Up TheHorse.com/AAEP2018 have beneficial applications for lameness examinations and standing surgery. Anesthetizing Minis, Mules, & More When it comes to putting equids such as mules and Miniature Horses under general anesthesia, vets must factor in those animals' physical and behavioral differences. Nora Matthews, DVM, Dipl. ACVAA, a professor at Texas A&M Uni- versity's College of Veterinary Medicine & Biomedical Sciences, in College Station, described how to go about it. Miniature Horses Because these equids are so small, the vet needs to not only calculate smaller anesthesia doses but also make equipment modifications, such as using smaller syringes and needles. Minis are prone to anesthesia-related complications, particularly fluid volume overload and hypothermia. Matthews also advised vets to be aware of abnor- malities common in dwarf Minis that could affect induction or recovery, such as musculoskeletal issues, collapsed tracheas, and upper airways that make intubation difficult. Another common problem? "Many Minis are very naughty and may not cooperate for injections," she said, adding that their size does make them easy to restrain and lift during recovery. Mules These donkey/horse hybrids dif- fer from horses physically and pharma- cokinetically (how they process drugs). Their typically thicker skin requires thicker-gauge needles. Mules do not dis- play pain as readily as horses might, said Matthews, and you might not recognize discomfort until it's severe. Mules metabolize anesthesia drugs faster than horses do, often requiring 50% more of some types, such as the α-2 agonists, Matthews said. "You don't have as much surgery time as with a horse, so be prepared to redose," she said. Mules also behave differently, and "their intelligence is highly underrated," she said. This can make recovery smooth, however, as mules can be calmer than horses when waking up from anesthesia. Hybrids and Zebras While there's little information on anesthetizing zebras and any variety of zebra/horse/donkey hybrid, Matthews recommended treating them like donkeys, mules, or unhandled horses. Just remember: "Zebras bite," she said. How to Sedate and Anesthetize Untrained Horses Working with horses that have had little to no handling can be dangerous for both animal and human. It's particularly chal- lenging to get them sedated and anesthe- tized for procedures such as castration. "Untouchable horses may vary from truly feral horses in open range areas to unhandled youngsters in the clinic or pasture environment," said Matthews. "All are potentially dangerous and require careful assessment of the patient as well as what facilities and personnel are available." Feral Horses Truly feral horses live in a herd on the range where there's no access to corrals, chutes, or fenced areas. So, vets typically dart them with sedatives. Darting in open terrain, however, has its dangers. "The drugs take 10 to 15 minutes to be effective," said Matthews. "Horses can travel some distance into environmental hazards" during this time. Drugged and recovering horses also become vulnerable to predators and dominant herdmates. She advised recruiting someone experi- enced with darting to avoid inadvertently striking horses in the abdomen or chest. Undomesticated Horses Matthews said horses that fall into this category include mustangs in Bureau of Land Manage- ment holding facilities and rodeo bucking horses. These animals have been handled minimally and are accustomed to stand- ing in cattle or roping chutes. She said they're typically comfortable here and can be sedated or anesthetized using a pole syringe if needed. Just make sure they don't get tangled in the chute in the process. Matthews noted it often takes at least two to three times the standard dosage in these horses for the drugs to be effective. Once recumbent (lying down), you can transport the horse for treatment. General anesthesia recovery usually occurs in a stall or a corral. Matthews recommended placing a towel over a horse's eyes during this process, providing as much padding as possible (if in a stall), administering a little sedative, and leav- ing him alone. Trying to get too involved in the recovery can be dangerous. Uneducated Young Horses This group includes weanlings to 2-year-olds without much handling, said Matthews. She suggested first giving an oral seda- tive gel, such as detomidine, and waiting 40 minutes for it to take full effect before inducing anesthesia. This is an off-label use of the drug, but she says it's safer for all involved. Vets handle recovery as they would in other minimally handled horses. In closing, said Matthews, all horses and all anesthesia are inherently danger- ous. Evaluate each situation, plan for the risks, and make sure you're equipped for success before starting, she said. h ONLINE extras Visit TheHorse.com/AAEP2018 ■ Vet: Practitioners Need Alternative Methods of Euthanizing Horses. TheHorse.com/166167 ISTOCK.COM Mules metabolize anesthesia drugs faster than horses do, often requiring 50% more of some types.

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