Caring for Long Ears
- Aug 1, 2012
A sturdy little donkey grazes happily in a roadside pasture, ears flopping and tail swishing. His belly is round, his feet solid, and his thick, coarse coat appears as if it could protect him from even the nastiest weather. Considering this typical image of a donkey in good health, it's no wonder some people believe mules and donkeys to be so very durable, compared with horses, that they are immune to many equine diseases or conditions. This, however, is a myth.
"Donkeys and mules (offspring of a male donkey and a mare) are not immune, just more resistant," says Robert M. Miller, DVM, an equine veterinarian from Thousand Oaks, Calif., who has owned and treated donkeys and mules for decades. "They are injured less often, less prone to colic, and less apt to develop common equine illness, with a handful of exceptions."
Despite their reputation for hardiness, donkeys and mules require the same basic care approaches that horses do, such as teeth floating, hoof maintenance, routine vaccinations, and deworming. What's more, they are even prone to health issues unique to their kind.
Common Health Issues
Veterinarians must take into consideration certain physical and metabolic differences when treating these animals. For instance, donkeys and some mules have smaller nostrils and nasal passages than do same-sized horses, which can be a limiting factor when veterinarians need to pass a nasogastric (stomach) tube to treat issues such as choke or colic. Since they were originally desert animals, their thick hair lacks the insulating undercoat that horses possess, leaving them vulnerable to bronchitis and pneumonia if it gets cold and wet. And donkey skin is typically thicker than that of horses--so when administering medications or fluids intravenously, the veterinarian frequently uses a different needle angle (to go deeper) when inserting it into the vein.
Also due to their history as desert dwellers, donkeys can survive longer in certain climates than horses. Due to this durability, their fluid balances and drug metabolism are different than in horses. Donkeys metabolize some drugs faster than horses, which affects anesthetic duration.
So, keeping in mind some of these differences, let's take a look at specific conditions these long-eared equids might face:
Respiratory disease The late Tex Taylor, DVM, who taught at Texas A&M University, observed that respiratory diseases are more prevalent in donkeys than in mules or horses. Taylor was widely recognized in the veterinary community as a donkey and mule expert, and in the late 1990s he published a handout to help practitioners understand and treat these animals better.
In the handout he wrote that veterinarians often see severe outbreaks of viral respiratory infections in donkey herds, and young animals might die in spite of treatment. He recommended conducting transtracheal washes for culture and sensitivity tests at first indication of disease. He also said it's important to put young animals on steroids (such as dexamethasone)--sometimes at higher dosages and for longer durations than would be recommended for horses--to reduce fluid formation in the lungs. He recommended checking affected donkeys' temperature, pulse, and respiration values twice daily. Taylor instructed veterinarians to treat any donkey with an elevated temperature or nasal discharge, or if the animal goes off feed or appears depressed.
Occasionally, veterinarians have linked equine influenza virus to these outbreaks, but usually it's neither a common strain nor one included in influenza vaccines. Taylor reported that older animals usually show milder influenza signs similar to those horses display (e.g., fever, cough, and nasal discharge).
Hyperlipemia This disease usually results from rapid reduction of nutrients in the diet. "Stress can also precipitate this, such as the stress of foaling, transportation, or being without food," says Sybil Sewell, co-founder of the Canadian Donkey and Mule Association and Alberta Donkey and Mule Club, in Leslieville, Alberta. "It particularly affects obese donkeys. The excess fat in the body is broken down and mobilized into the bloodstream too quickly and causes liver and organ damage, with high mortality rates."
Parasites Another medical condition more common in mules and donkeys than in horses is what's known as jack sores, or summer sores (habronemiasis). Flies carry and deposit Draschia and Habronema stomach worm larvae that can cause granulomas when they infect small wounds or other moist areas of the animal's body, such as the conjunctiva of the eye.
"Better deworming drugs like ivermectin (which kills the tiny larvae in these sores) have reduced the incidence of this problem," says Miller.
Lungworms (Dictyocaulus arnfieldi) are also more common in donkeys than in horses and cause coughing and signs of lung irritation similar to heaves. Unless donkeys are dewormed routinely, they might harbor these parasites and pass them to horses housed in the same pastures (via worms passed in manure and ingested during grazing). Taylor suggested fecal sampling and deworming affected donkeys with ivermectin twice a year to reduce the threat of lungworms.
Skin conditions Donkeys and mules also seem more susceptible to sarcoids (noncancerous skin tumors). "Horse sarcoids are usually not difficult to clear up with modern treatments," says Carl Lind, DVM, of Bishop Veterinary Hospital, in Bishop, Calif., "Mule or donkey sarcoids, by contrast, tend to recur or spread from the initial location." (See TheHorse.com/19898 for common sarcoid treatment suggestions.)
"Another problem donkeys have more often than horses is lice--maybe because of the longer hair coat," says Sewell. "A new animal to the herd may spread lice to the others if not isolated and treated. You may not realize the animal has lice because they are hidden in the long hair. This can be easily controlled with delousing powders, but if neglected lice can quickly cause serious hair loss."
Donkeys, with their longer hair, are also more susceptible to rain rot than horses. "If there's a lot of rain in the fall and no shelter, donkeys may get this skin problem," Sewell says. "Clumps of hair fall out, and bald patches develop."
Dental issues Owners should get their donkeys' and mules' teeth checked and floated routinely. "Since donkeys and mules live longer than horses, teeth become an issue in older animals," Lind says. And because of mules' and donkeys' inclination to protect themselves (e.g., kick), he suggests sedating them for safety when floating teeth. "I've seen them fight through sedation more than a horse will," he adds, due to their quick metabolism as well as ¬behavior tendencies.
Neonatal isoerythrolysis (NI) Also called foal jaundice, neonatal isoerythrolysis is a condition in which the pregnant mare creates antibodies against the fetus' red blood cells, if it inherits a blood type from the sire that's incompatible with the mare. This problem occurs more frequently (about 10% of the time) in mule foals because donkeys possess a blood component that mares do not have, explains Todd Bettin, DVM, of Breda Lake View Veterinary Services, in Lake View, Iowa.
"Normally there is very little blood going back and forth between mare and foal across the placenta (unless there's placental disease), but there is an increased amount of exchanged blood in mule foals," he says.
Newborn foals gain instant protection against disease if they ingest a proper amount of their dam's colostrum soon after birth. But if the colostrum also contains mare antibodies against the foal's own red blood cells, it can be deadly--if the antibodies destroy enough of his red blood cells. Severely affected foals show signs of jaundice (yellow mucous membranes) due to red blood cell breakdown, the cells' pigment leaking out into the tissues, and anemia, Bettin said.
Castration complications Veterinarians must take extra care to prevent excessive bleeding when castrating donkeys or mules, as these animals have larger testicles and, thus, larger blood vessels in the groin region than horses. Most recommend castrating colts that have both testicles descended before testicles and blood vessels become large--generally before 6 months of age--to prevent aggressive behavior.
"Complete ligation (suturing) of the spermatic artery in donkeys is very important," says Sewell. "I won't use a vet who doesn't put a stitch in and make sure those arteries are closed--as well as using the emasculator to crush the arteries and spermatic cord."
Besnoitiosis This rare parasitic disease caused by Besnoitia bennetti surfaced in North American donkeys in 2011 and is characterized by the development of cystic lesions both externally and in the throat and eyes. Currently, the mode of transmission is unknown, and there are no known effective treatments.
Donkeys and mules don't experience as many lameness-causing injuries such as bowed tendons, torn ligaments, or navicular syndrome as horses do, but these problems do occur. Incidentally, "we do see more ringbone (a degenerative disease of the pastern and coffin joints) in mules, however, than in horses," says Lind. "This is partly because of what we ask them to do. Mules that jump may suffer more (foot) concussion because they don't have a big round foot like a Thoroughbred or Warmblood."
Sewell adds, "People are now using donkeys and mules in the show ring, to do all the things horses do, putting a lot of stress on their legs. Now we are seeing some of the horse leg problems occurring in donkeys and mules, especially if they are not carefully bred to have enough bone and leg structure. I've seen mammoth donkeys with 'toothpick' legs. Yet because they are 15 hands tall, they are asked to carry a rider ... plus Western tack at a young age."
Maturity rate also plays a role in soundness: Donkeys and mules develop more slowly than horses, and knee closure (when the carpal growth plates change from cartilage to bone) takes longer. Sewell cites studies in which researchers evaluated carpal maturity in donkeys: Miniature Donkeys' knees closed at about 3 years of age (as a horse's would), but mules' and larger donkeys' knees didn't close completely until they were 4 or older.
Even though donkeys traditionally carry heavy burdens with ease, they do it at a slow walk. "In their native countries they are not asked to barrel race; they are asked to walk five miles back and forth to the local market," says Sewell. "When training a donkey/mule, give it time to grow up so it can stay sound and give many years of useful service."
And while bred for slow travel, it's important to note that "donkeys can perform in speed events--just about anything you'd do with a horse," she adds. "Just don't rush them into this at a young age."
Handling for Health Care
Mules and donkeys have a stronger self-preservation instinct than horses and are quick to defend themselves. "They have tremendous ability to kick (as a self-preservation tactic)," Miller notes. "Unlike a horse, you can be standing at the animal's head and a mule can reach you with its hind foot."
Because of this tendency, it can be especially challenging to perform health care and management procedures (e.g., deworming, vaccinating) on donkeys or mules if they haven't been handled consistently and properly. Getting them accustomed to this type of handling will foster respect for and trust in the handler, not to mention safety for both parties.
Starting early is key: Imprint training (handling the neonatal foal and habituating him to various stimuli immediately after birth) can be valuable for future handling and training of mules and donkeys, says Miller, allowing owners to address resistance to common procedures early.
Overall, Lind emphasizes using common sense when working with these equids. "They aren't any more needle-shy than a horse or more difficult to worm, float their teeth, or shoe, as long as you've handled them properly--with good experiences rather than bad ones," he observes. "They remember the bad ones and are less forgiving than a horse." Thus, keep painful and irritating experiences to a minimum, or the animal might become more difficult to handle for routine treatments.
As for tolerance, donkeys are quite stoic, responding to stimuli with obstinance rather than a flurry of activity. This naturally stoic nature can serve as a disadvantage to veterinarians when diagnosing medical issues, as it can mask an illness' seriousness.
If you own donkeys and/or mules, learn as much as you can about their nature, unique health characteristics, and handling considerations. Doing so, along with seeking the guidance of your veterinarian, will prepare you to recognize and address potential problems.
About the Author
Heather Smith Thomas ranches with her husband near Salmon, Idaho, raising cattle and a few horses. She has a B.A. in English and history from University of Puget Sound (1966). She has raised and trained horses for 50 years, and has been writing freelance articles and books nearly that long, publishing 20 books and more than 9,000 articles for horse and livestock publications. Some of her books include Understanding Equine Hoof Care, The Horse Conformation Handbook, Care and Management of Horses, Storey's Guide to Raising Horses and Storey's Guide to Training Horses. Besides having her own blog, www.heathersmiththomas.blogspot.com, she writes a biweekly blog at http://insidestorey.blogspot.com that comes out on Tuesdays.
POLL: Horse Barn Air Quality