Article & photos by Nancy Brannon, Ph.D.
The University of Tennessee College of Veterinary Medicine (UTCVM) offered its annual Horse Owners Conference on Saturday March 7, 2020 in the Hollingsworth Auditorium on the UT Ag Campus, Knoxville, Tennessee. The conference offered a range of information on the latest in horse health care from the staff veterinarians, as well as presentations from sponsors Purina, Dechra, and Horsepower Technologies. Even if you have attended this conference previously, there’s always something new to learn from the UTCVM veterinarians and invited guests. The all-day conference provided breakfast and lunch for participants and breaks that allowed opportunities for one-on-one conversations with veterinarians and sponsors. The highly informative event is well worth the modest cost of $10 (early registration) or $20 (late registration).
Conference topics covered a range of horse health issues for both experienced and new owners to learn about their animal inside and out: dentistry, lameness and rehabilitation, emergencies and first aid, nutrition, metabolic syndrome, navicular syndrome and bisphosphonates, laparoscopic procedures, toxic plants, plus mules and donkeys. Dr. Phil Jones, an equine surgery specialist at UTCVM, hosted the conference, introducing each speaker with “punny” jokes in his “slightly” Australian accent that elicited laughter as well as moans and groans. Following is a more in-depth account of the topics.
Common Equine Emergencies & First Aid
The conference began with Dr. Meggan Graves’ presentation on “Common Equine Emergencies & First Aid.” UTCVM provided some “Large Animal Emergency and Critical Care” information sheets to take home: one on how to take your horse’s vital signs; one on colic; one on common equine eye problems; and one on tick-borne disease – equine prioplasmosis, plus a multi-page handout on the Asian Longhorned Tick, which have been shown to carry the causative agents for anaplasmosis, babesiosis, ehrlichiosis, theilerosis, and rickettsiosis, as well as several viruses. These ticks have potential impacts on livestock and wildlife, with the ability to feed in large populations on warm-blooded host animals.
Next, Dr. Melissa Hines gave an “Update on Equine Pituitary Disease and Metabolic Syndrome.” Equine Cushing’s Disease, also known as PPID – pituitary pars intermedia dysfunction, is a disorder of the endocrine system. Cushing’s Disease is caused by enlargement of the pars intermedia of the pituitary gland. Dysfunction of the pars intermedia results in the increased release of several hormones, including ACTH (adrenocorticotropin hormone). ACTH travels through the horse’s blood stream and causes the adrenal glands (located near the kidneys) to increase production of cortisol, a type of steroid. It is this overproduction of cortisol that affects the horse and can explain the majority of clinical signs seen in this condition. Recurrent and often unexplained bouts of laminitis along with an abnormal hair coat are two of the most common clinical signs of a horse with Cushing’s.
Equine Metabolic Syndrome (EMS) describes horses presenting with obesity and/or large regional fat deposits, insulin resistance, and recurrent laminitis. As with Cushing’s Disease, the association between EMS and recurrent laminitis is believed to be a link between the occurrence of insulin resistance and the predisposition for laminitis.
Insulin resistance is a reduction of the horse’s ability to respond appropriately to the hormone insulin, which is involved in the uptake of glucose from the bloodstream following eating and its storage in cells. With insulin resistance, this very important mechanism no longer functions properly. The body tries to counteract its own insensitivity to insulin by producing more and more insulin, and it is the elevated level of insulin that indicates insulin resistance is occurring.
Equine Dentistry: Oral Health Care for Your Horse
Dr. Eric Martin emphasized the importance of routine equine dental care, and began his presentation with an explanation of the horse’s masticatory cycle. Naturally, horses graze 10 – 17 hours per day. Averaging 60 chews per minute, that’s 3600 chews per hour; grazing ten hours a day, that’s 36,000 chews per day, totaling to about 13 million chews a year!
Because of such constant use and wear, a good, thorough dental exam is needed regularly, which should include observing the far back of the mouth, for which the horse may need to be sedated.
The horse’s tooth has an undulating surface, made up of the enamel and cementum, not living tissues, and dentin, which seals and protects the pulp cavity. Horse owners often associate dental care with floating, which simply means to level a surface. Martin emphasized, “Just take off what the horse doesn’t wear down.” Every horse needs a regular good oral exam, which includes an extra-oral exam; evaluation of occlusion, of soft tissue/arcades, of the periodontal structure, and of the endodontic structures of the clinic crown.
What signs can a horse owner observe that indicate dental disease?
· Deviation of the head to one side while chewing
· Quidding (dropping grain or semi-chewed wads of hay/grass)
· Sudden change in mastication pattern
· Bitting problems
· Halitosis (bad breath)
· Excessive fecal fiber length (> ¼ inch)
· Weight loss
· Choke
· Colic
· Avoidance behaviors; change in attitude; facial expression
The horse’s mature dentition occurs at age 5 and they have these teeth for 15 years, on average. Dr. Martin explained the stages of teeth development in horses and the kinds of potential problems that can occur at each age cycle: from birth to 2 years; 2 - 5 years as the adult teeth are coming in (babies don’t have the same number of teeth as adults; horses gain all their molars as adults); and 5- 15 years; 15-25 years, the stage at which changes associated with age become apparent; and over 25 years. This is the end stage of dentition when there is an absence of molar to molar contact, teeth may fall out, and diet considerations are critical. This is where senior feeds are important to give older horses proper nutrition that they can’t get from grazing any more.
He discussed overbites and underbites; wolf teeth (not all wolf teeth cause problems); gingivitis; losing deciduous teeth; caps (deciduous teeth retained); and tartar. “The backyard horse primarily on grass is much less likely to have tooth problems,” Martin explained. It’s chewing the grains and concentrates that wears down teeth faster.
Horses do get cavities, but as the horse’s teeth wear and erupt, the cavities may “take care of themselves. Horses’ teeth are so resilient!” For additional information, link to Dr. Martin’s video on “Equine Dental Care: Beyond Floating” at https://vetmed.tennessee.edu/News/Pages/NewsArticle.aspx?news439 and https://www.youtube.com/watch?v=S7ogc2aR288
Use of Bisphosphonates for Clinical Signs of Navicular Syndrome: OSPHOS® presentation
Following the break, Alex Riddle with Dechra Pharmaceuticals explained their product OSPHOS®, an intramuscular bisphosphonate injection for control of the clinical signs associated with navicular syndrome in horses four years and older. Riddle is from Lexington, Kentucky and his father is an equine veterinarian.
Riddle explained how bones undergo constant turnover, with osteoblasts forming bone and osteoclasts resorbing old bone. In normal bone tissue, there is a balance between bone formation and bone resorption. But in diseased bone, the balance is disrupted. Bisphosphonates inhibit bone resorption by encouraging osteoclasts to undergo cell death, and reduce bone breakdown.
In normal bone remodeling, bone resorption is complete within ~ 3 weeks, but bone formation takes ~3 months. Osteoblast activity and Osteoclast activity are “coupled” to work together, so that the amount of bone formed equals the amount destroyed.
The navicular bone is a tiny bone that sits deep within the hoof at the back junction of the coffin bone and the short pastern bone. On the upper (proximal) aspect of the bone is the collateral sesamoidean ligament, which attaches the navicular bone to the distal end of the short pastern bone. On the lower (distal) aspect of the bone are the impar ligaments, which attach the navicular bone to the coffin bone. Cushioning the navicular bone is a soft serous sac called the navicular bursa.
The navicular bone provides a gliding surface at the point where the deep digital flexor tendon changes angle; the tendon courses down the back of the cannon bone and bends around the back of the fetlock, between the proximal sesamoid bones, then makes a sharp bend over the navicular bone and attaches on the bottom of the coffin bone. Needless to say, this tiny bone bears a lot of load pressure, especially when the horse is doing a lot of work, particularly movement changes.
Riddle explained the chronic intermittent forelimb lameness that is associated with pain arising from the navicular bone and related soft tissue structures. Sometimes this is also called podotrochlear apparatus syndrome or caudal heel pain, and he explained the symptoms.
There are two types of bisphosphonates: nitrogenous and non-nitrogenous. Osphos® is an FDA-approved non-nitrogenous bisphosphonate for use in horses. Non-nitrogenous bisphosphonates inhibit osteoclast recruitment, adhesion, differentiation, and resorptive activity, and induce cell death. Bisphosphonate drugs have the ability to bind to bone mineral and become internalized by osteoclasts. They “stick” to calcium and bind to it. Bisphosphonates are incorporated into the bone mineral and are gradually released over months to years. Navicular syndrome is a bone resorptive condition, i.e., horses with navicular syndrome undergo loss of bone. Dechra states that “treatment with OSPHOS® (clodronate injection) is effective at controlling the clinical signs associated with navicular syndrome in horses 4 years and older.”
Riddle cited the study “Evaluation of the clinical efficacy of OSPHOS® for the control of the clinical signs associated with navicular syndrome in horses,” by Rob Boswell, David Kolb, John Janicek, Stuart Shoemaker, Bradley King, and Michael Frevel. I could not find this study online, but did find a Freedom of Information Summary of this work. Here is the link: https://animaldrugsatfda.fda.gov/adafda/app/search/public/document/downloadFoi/923. The study was done from Jan. 2010 to June 2011.
There are precautions about use and side effects of the drug. Find out more information at www.osphos.com. The product brochure at: http://www.osphos.com/includes/pdf/Dechra-Osphos-Legal-Package-Insert.pdf gives detailed information about the precautions and side effects on page 4.
Editor’s Note: This article “Bisphosphonate use in the horse: what is good and what is not?” (June 2014) by Alexis Mitchell, Ashlee E. Watts, Frank H. ebetino, and Larry J. Suva may be of interest. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6591999/
Ovariectomy and other Laparoscopic Procedures
Dr. Elizabeth Collar, one of the new equine surgeons at UTCVM, explained laparoscopic procedures and showed some videos of what surgeons actually see inside the horse with their tiny cameras.
Laparoscopy is minimally invasive, aka “keyhole,” surgery. Equine surgeons make small incisions, and then insert a camera and surgical instruments to do the procedure. Laparoscopy refers to surgery in the abdomen; thoracoscopy refers to surgery in the chest cavity. While human laparoscopy dates to the early 1900s, equine laparoscopy was first done in the early 1970s, became common in the 1990s, and is the “gold standard” today, she said. The primary laparoscopic procedures used today are ovary removal and internal teste removal. The benefits to this type of surgery are that it minimizes risks and recovery is quicker than with standard surgery that opens up the whole area.
The horse’s “sleep lock” system, or stay apparatus, which allows the horse to sleep standing up, is an advantage for the surgeon who can operate on a standing horse. In the standing position, the surgeon can see the upper (dorsal) abdomen, such as small colon, rectum, spleen, kidney, liver, and lung. If the horse is put under general anesthesia and flipped upside down for surgery, the surgeon can only see what’s in the lower half of the abdomen.
The standing procedure is best for ovary location and removal. Similar reasons for gelding a stallion are given for removing a mare’s ovaries: aggressive behavior, excitable, excessive signs of heat. Ovaries infected with granulose cell tumors, or other pathologies, are also reasons to remove.
Post-op recovery is relatively quick, with discharge a day after surgery, use of NSAIDS and antibiotics, and return to exercise in 3-4 weeks.
Another common laparoscopic procedure is cryptorchidectomy: removing an undescended testicle.
In conclusion, Collar said that elective ovariectomy can improve undesirable behavior in mares. Laparoscopy provides a range of treatment options that are safe, cost effective, and provides diagnostic and treatment opportunities for a variety of other issues.
Equine Nutrition from Purina
Just before lunch, Purina Equine Nutritionist, Anna Pesta, Ph.D. provided information about nutritional support for horses of advancing age. She asked the audience: When does a horse become a senior? Generally, “when the teeth or guts start to go; as soon as the horse can’t keep his body condition as he used to,” and not at a specific age, she said. Senior feeds were developed in 1993 to address an older horse’s decreased utilization of protein, fiber, and phosphorus.
Nutritionally related senior issues include: systemic effects of aging on immunity; over or under weight; poor dentition; and PPID, IR, or EMS. Choose the right feeding program to address these issues.
Immunosenescence refers to the gradual deterioration of the immune system brought on by natural age advancement. Decline in immune function means decreased ability to resist infection, reduced response to vaccinations, and therefore, increased susceptibility to disease. Other signs of aging can include weight loss and decreased body condition, not maintaining muscle mass, or changes in eating behavior. Aging can also affect the senior horse in ways that aren’t always visible, e.g., decline in immune function can affect joint mobility; and chronic low-grade inflammation is also associated with aging.
Purina has partnered with the Gluck Equine Research Center at the University of Kentucky to address these aging issues. Resulting from this research is the inclusion of ActivAge prebiotic in Purina senior feeds. A prebiotic supports the growth of beneficial organisms in the digestive tract, and Purina has developed the specific strain of ActivAge to support immune function in aging horses. Pesta said to think of a prebiotic as “bug food” and a probiotic as the “bug.”
Pesta explained the role of and source of fats in the equine diet, and how to properly feed for weight gain. Most people want to increase fat in the horse’s diet, which is calorie dense and good for coat and hair. But fat alone is not going to increase the BCS quickly, especially in senior horses. Fiber is digested in the hindgut and too much unsaturated fat depresses hindgut digestion. What the horses are missing is digestible fiber calories and may not need more fat. She advised to get better hay, feed more of it, and to consider feeding a senior feed. She said that concentrated calories with a full balance of nutrition produce the best results.
Pesta explained the difference between senior or complete feeds and concentrate feeds. Complete feeds give partial to total forage replacement with a 0.6% body weight (BW) feeding rate. She said it’s not the crude fiber percentage on the feed tag that’s important; it’s the type of fiber. Concentrate feeds are fed with forage at a 0.3% BW feeding rate.
Then she explained the proper nutritional requirements for weight loss. Easy keeper, “efficient,” horses need no unnecessary calories from sugar, starch, and fat, but do need proper protein, vitamins, and minerals levels – especially with reduced forages and grazing. They do need enough fiber for hindgut health. A ration balancer is essential in a diet to reduce weight. And to keep these horses from eating the barn, they do need “eating satisfaction,” so extend their meal time and balance meals with exercise. Pesta gave several weight reduction feed program options.
Next she turned to Insulin Resistant and Cushing’s disease horses. First, get the diagnostics from your veterinarian to determine if the horse has IR or Cushing’s or both. The feed plan will depend on which or both diseases the horse may have.
With insulin resistance, the main objective is to limit starches and sugars in the ration. If the IR horse is easy keeping and/or fat, putting the horse on a lower calorie diet to help them lost weight can actually help improve the insulin numbers. They need moderate quality hay (not free choice) and proper nutrients through a ration balancer. Keep the meal size small with low starch and low sugar in each meal.
Cushing’s horses need a moderate carbohydrate diet and excellent quality nutrition. If they are an easy keeper, a ration balancer can help them. She emphasized, “Don’t starve your Cushing’s horse.” If muscle wasting proceeds, the horse can benefit from a more moderate carbohydrate diet with more calories, e.g., Purina Equine Senior Active. If the horse with Cushing’s is old and not doing well, traditional Purina Equine Senior may be the feed choice for them.
What if your senior horse has a fiber deficiency because they can’t eat hay, or they eat hay but do not get the nutrients from it? Options include a complete senior feed, soaked hay cubes, and beet pulp shreds.
Seniors are more prone to choke, so she went over the causes and ways to minimize this risk.
Finally, she explained how to feed the extremely emaciated, under-nourished horse, which includes an alfalfa re-feeding protocol combined with Equine Senior, and good veterinary care and oversight. But go SLOWLY, she emphasized or you can make their condition worse.
After her talk, Purina generously provided lunch for the conference participants.
Evaluating Lameness
After lunch, it was time for Dr. Phillip Jones to get the spotlight himself, speaking on “Evaluating Lameness: How you can help your veterinarian help your horse.”
He went through the lameness examination procedure to determine the source of lameness in a horse, beginning with an accurate history of the horse. He recommended keeping a diary on your horse.
Beginning with observation of the horse standing, he looks at conformation, for any asymmetries and muscle atrophy, and any evidence of foot problems, such as dragging, hoof/pastern angle, and heel height. “Pay attention to the hind feet,” he said, and explained that each horse has its own “normal.”
He then looks at the horse moving on various surfaces – hard, firm, soft, gravel, sand arenas. Observe at a walk: head movement, placement of feet, do they walk straight, flexion and extension of each joint, cranial (forward) phase of stride (For a hind leg, the cranial phase occurs when the lower leg is under the body of the horse, and the caudal phase is when the limb is out behind the body of the horse), turning both directions, and ear position and general attitude.
Observe at the trot in hand, the horse moving in a straight line, from behind and the sides. Then observe the horse on a lunge line in both directions. He also has a person ride the horse to ascertain the effect of extra weight on the horse. Next come flexion tests.
He emphasized doing a complete physical exam and keeping the order of the body parts consistent when examining the horse. Take videos of the horse and play them in slow motion. Move around the horse and look at it from all sides. Observe how the whole hind end moves together. Then examine the front limb.
When observing the head bobbing that comes with lameness, a good rule of thumb to remember is “down is sound;” the horse’s head bobs down on the sound leg.
He explained that a lot of lamenesses can look the same, so the veterinarian must go through the ordered progression of nerve blocks to properly diagnose lameness.
Jones had a lot of good slides showing asymmetries and slow motion videos to help the audience ascertain which leg was lame.
Donkeys are Different
The tone changed when Dr. Neal Valk came to the podium; “Donkeys are Different” was the title of his presentation. The donkey (Equus africanus asinus) and the mule (Equus mulus) are closely related to, but distinctly different from, the horse (Equus caballus). If you weren’t endeared with donkeys, or respected them, before his presentation, you would afterwards. Owning several of “the world’s greatest donkeys” himself, he has much to praise in these equids.
Dr. Valk pointed out the importance of “looking at the evolutionary history of the animal you’re working with.” Donkeys evolved in north Africa, adapted to a harsh, arid, barren environment. They do not live in herds or bands due to the scarcity of vegetation. Most live solitary lives, coming together only at water sources or during breeding. They have very large ears, which are adapted for hearing over long distances and dissipating heat, and very loud voices for communicating over long distances. Their body and limbs are designed for agility in rough terrain, and are less of a “flight” creature than the horse.
Valk explained: “Donkeys stop first and size up the situation. They are more logical and reasonable than horses and almost totally predictable. Horses can be very unpredictable. Horses move away from pressure, but donkeys move into pressure. And donkeys are very talented at reproducing!”
He gave the baseline TPR for adult donkeys and examples of health care considerations for donkeys. They are susceptible to many of the same diseases that horses are, but appear to be more resistant than horses to some. On the other hand, some horse diseases occur in more severe forms in affected donkeys.
Donkeys tend to have a more “robust” digestive system than horses do.
Donkeys are more “stoic” than horses and are less likely to manifest symptoms of disease until the condition is advanced.
Donkeys appear to tolerate heavy parasite burdens better than horses, even though the parasites are the same between the species. Donkeys are inapparent carriers of lungworms (Dictyocaulus arnfieldii), a parasite which can cause severe respiratory disease in horses.
How to care for you donkey? He recommends administering core vaccines (EWT/WNV and rabies) to donkeys; deworming should be based on fecal egg counts; and regular dental exams and routine dental maintenance.
One of the major health issues he sees in donkeys is obesity. Consider the evolutionary history of donkeys, who are not designed to eat lush grass or concentrates. They are “browsers,” not strict grazers. His recommended diet is 1.2 to 1.5% of the ideal BW of rye or barley straw per day. Yes, straw! Grass hay is too rich and lush pasture should almost always be avoided, as should concentrates. He says his donkeys do well and maintain a healthy body weight living on a semi-dry lot with constant access to medium quality round bales. Fresh water and a salt block are always available.
A common problem for donkeys is hyperlipaemia, a disease caused by too much fat in the blood. To treat/prevent this problem, limit or eliminate access to pasture (but not to forage); avoid high energy feeds; feed hay with <10 to 12% NSC, utilize slow feeders, but DO NOT fast or starve your donkey (results in hyperlipaemia). In addition to the feeding regimen, increase their exercise. He says that track systems work well to reduce access to pasture while providing an enriched environment which stimulates natural movement. In other words, built a track around the perimeter fence and place hay flakes at intervals around the track so that donkeys have to travel to get hay.
Provide browse to your donkeys. Many woody and herbaceous plants are suitable as browse, which satisfies the donkey’s need to chew and provides psychological stimulation. But research the options carefully, as many plants (especially ornamentals) are toxic. One thing he does is to “recycle” Christmas trees as browse for his donkeys.
Finally, routine hoof maintenance/trimming is essential. Donkey hooves are often neglected due to owner misinformation or lack of cooperation on the donkey’s part. Neglect can result in bizarre hoof capsule distortions that cause pain and lameness. Their hooves should be trimmed every 6 to 12 weeks depending on hoof growth rate and environmental conditions. Because of the small stature of many donkeys, trimming can be a challenge, but holding the hooves low and close to the body facilitates hoof care.
Donkeys can founder, which is primarily caused by diet and the high incidence of EMS/insulin resistance in donkeys. PPID is also frequently diagnosed in aged donkeys. Dietary control is the key to successful treatment. However, donkeys do not present founder as horses do, but more likely in decreased movement and more time spent in recumbency, along with elevated digital pulses. Again, diet is the key to management, along with NSAIDs to temporarily relieve pain and correct hoof trimming to improve the mechanics and comfort.
White line disease is endemic in our area and Valk believes it is a manifestation of chronic laminitis. But the disease is very easy to resolve in the donkey, if treated appropriately.
He completed his presentation by debunking “mule myths.” Mules don’t founder (they do). Mules never overeat (wrong). Mules never get arthritis or navicular disease (not true). Mules never colic (not often, but sometimes).
FastTrack™ - Rehabilitative Orthotic
Victoria Boutelle with Horsepower Technologies introduced the FastTrack™ an equine orthotic that actually looks like a brace, which fits on the canon bone and the pastern below the fetlock joint. It is designed to help rehabilitate flexor apparatus soft tissues (tendons and ligaments) which are at risk during extension of the fetlock joint. It supports the fetlock joint and limits movement of the joint, allowing the horse to move while the soft tissues heal.
The device is heated to exactly fit the particular horse, but can be re-heated up to three times to fit other horses. It is sold directly to veterinarians, who can sell or rent the device to their clients. It is only worn for 2 to 3 hours a day, but this allows for the horse to have light exercise as healing is ongoing.
Find more information about this orthotic device at: https://www.horsepowertech.com/
Toxic Plants
Dr. Carla Sommardahl discussed some of the common plants that are toxic to horses. She began with fescue, a grass that is NOT toxic, but may contain a fungus that secrets toxins. There are over 35 million acres in the U.S. that contain this perennial cool season grass, and it is good forage for most horses, especially geldings and non-reproducing mares. The problem lies in the endophyte fungus that can cause problems in pregnant and lactating mares. It contributes to lowered conception rates, prolonged gestations, dystocias (difficult birth), weak foals, stillbirths, thickened placentas, and decreased prolactin levels, which leads to decreased colostrums and milk.
Pasture management can help prevent this situation. Test pastures and hay fields for the fungus, mow fields, remove broodmares from fescue grass and hay at least 30 days prior to breeding and at least 60-90 days prior to foaling. Then keep the mare and foal off fescue until weaning. Dr. Sommardahl said that baling does not kill the toxin and that the fungus likes to live on the fescue seed head.
Red Maple is another plant whose leaves are toxic when wilting. The toxin from red maple affects red blood cells, causes them to rupture and die off, and then the urine becomes red. She said that fresh leaves and autumn leaves that fall on their own are less toxic. The ones to be wary of are those that fall prematurely, such as a broken off branch. The Sugar Maple, which turns orangy in the fall, also has leaves that are toxic, especially spring and summer leaves. Dead fall leaves are less toxic.
Blister beetles build theirnests on the periphery of alfalfa fields, so sometimes the beetles get baled into alfalfa hay. Their bodies contain cantharadin toxin and can usually be found in clusters within bales. It only takes 2-3 beetles to very toxic to horses. Cantharadin toxicity is very irritating to all membranes contacted; the mouth and esophagus can be ulcerated; it can cause colic, kidney damage, and low blood calcium. So only buy certified Blister beetle free hay and inspect each flake before feeding it to your horse.
Crotalaria is a hardy annual with yellow flowers and it is generally not eaten by horses. But if they have nothing else to eat, they may eat it. Senecio is a multi-stemmed annual or perennial with small, daily-like yellow flowers. All parts of both these plants are toxic – fresh or dry. They can cause liver damage, which is cumulative and irreversible. Horses ingesting the toxin get “sleepy staggers” or “walking disease,” which can begin weeks or months after ingestion. They have weight loss and weakness, may show signs of jaundice, and can lead to coma or death.
Aflatoxins are molds that infect seed grains – wheat, corn, oats. Moldy corn contains fumonisin, which can cause brain damage. Monensin toxicity comes from lasolacid growth enhancing feed additives for cattle and poultry. It does not harm cows and poultry, but is toxic to horses. It damages muscles, especially the cardiac muscle.
Heavy metals that are toxic to humans are also toxic to horses, e.g., lead, copper.
Box Elder causes seasonal pasture myopathy, a potentially fatal disease that affects horses’ muscles. Commonly seen in the fall, the disease has been linked to seeds of the box elder tree, a specie of maple that contains hypoglycin A, a toxin.
Rhododendrons, Mountain Laurel, and Azaelas are all beautiful blooming shrubs, but toxic to horses. However, horses don’t really acquire a taste for Rhododendrons.
Oleander (grows in Florida) and Yeware other plants toxic to horses.
Cherry trees and their relatives, even wild cherry, can be toxic. Animals ingesting wilted cherry leaves experience the release of cyanide (HCN) into the bloodstream, a very potent toxin.
Poison hemlock, while it may have beautiful white flower clusters, gives off a bad odor when crushed, and horses rarely eat this plant because of its low palatability. However, poison hemlock plants harvested with hay maintain the toxic properties; so care should be taken to avoid feeding hay containing this plant.
Johnson Grass (Sorghum), Rye Grass, Dallis Grass can contain toxins which cause “staggers,” and can affect cattle, too. Sorghum toxicity causes the horse to lose bladder control. Dr. Sommardahl advised, “Mixed grass hay is better.”
Equine Rehabilitation
Last of the day’s topics was Dr. Karen Shaw’s presentation on “Return to Function: The Focus of Equine Rehabilitation.” Dr. Shaw is an equine sports medicine and rehabilitation resident at UTCVM.
First, what is rehabilitation? The treatment of injury or illness to decrease pain and restore function, and Shaw listed numerous benefits of physical rehabilitation.
From what illnesses/injuries do horses need rehabilitation? Shaw began with osteoarthritis, a bony degenerative condition. The osteoarthritis disease process includes cartilage loss, joint inflammation, subchondral bone change and new bone growth, with joint lining and capsule thickening. Inflammation and pain lead to reduced range of motion.
Treatments for inflammation include corticosteroids, and regenerative medicine therapies such as IRAP, Platelet Rich Plasma, and Pro-Stride.
Her recommended treatment for pain is extracorporeal shockwave therapy.
Then comes improving the reduced range of motion: with stretches, joint mobilizations, and therapeutic exercises – over raised poles and use of leg weights.
She addressed tendon/ligament injury – overloading or strain-induced injury. It begins with the acute inflammatory phase, disruption of the tendon structure. Next is the reparative or fibroblastic phase, the formation of scar tissue, followed by the remodeling phase improvement of fiber alignment and strength.
First, treatment of the swelling and inflammation involves cold therapy, compression, and laser therapy. She showed the use of immersion ice boots, Game Ready full leg wraps, salt water therapy, and laser therapy that stimulates cells and increases cell metabolism.
Regenerative medicine i.e., stem cells, are a treatment protocol for fiber disruption, along with rest and controlled exercise, along with custom orthotic boots such as the Horse Power Fast Track boots. She showed how normal tendon/ligament fibers are arranged in parallel structures, but with injury disruption, the fibers are torn. The stem cell therapy helps re-organize the fibers more like their original parallel structure.
The remodeling phase is a graduated control exercise program that can utilize the underwater treadmill, balance/proprioception training, and acupuncture and chiropractic medicine, which work synergistically.
For muscle conditions/atrophy, that result in weakness, disuse, pain, and muscle dysfunction, therapies for muscle weakness and disuse include electrical muscle stimulation and isometric contractions. To manage pain and dysfunction, acupuncture and chiropractic medicine work hand in hand, along with types of manual therapy like massage, myofascia release, and trigger point therapy. Rapid release technology is often used on scar tissue.
For treatment of wounds, especially those on a joint, therapeutic ultrasound, shockwave therapy, and laser therapy can be used to address scarring and fibrosis issues. The therapeutic ultrasound stimulates fibroblasts and increases cellular metabolism. Therapeutic exercises to improve range of motion include work over raised poles and underwater treadmill.
Dealing with neurological conditions – ataxia, weakness, proprioceptive deficits – utilizes similar exercises as some of the other injuries: proprioceptive re-training with an obstacle course, such as weaving in and out of cones, and balance pads, along with strengthening exercises.
Editor’s Note: I had learned of balance pads, promoted by Wendy Murdoch, but I remained skeptical about their benefit, even as she claimed that her Sure Foot balance pads could address and resolve many of the balance issues that horses incur. After Dr. Shaw’s presentation, I saw the rehabilitative benefit of balance pads to horses with neurologic conditions. Dr. Shaw said they help the horse regain balance and coordination, working on their proprioception.
This 2020 conference provided an abundance of information that covered the horse “from mouth to hoof,” as Dr. Phil Jones explained to the news media. Jones summarized: “What I have seen is that horses around the world are the same. Horses in Australia develop the same conditions as those here in America, and horse owners are the same, as well. Whether their horse is part of a business, an athlete competing in events, or a backyard pet, owners are passionate about their horses because they are part of their family. I grew up with horses myself. Just as with any family member, owners want their horse to be as healthy and as well cared for as possible; they are thirsty for knowledge that would allow them to provide for and care for their horses to the best of their ability. Today everyone has access to all sorts of information on the Internet. So we want to ensure they have access to reliable information, which is why we hosted this conference.” Here at the Mid-South Horse Review, it is our job to pass along factual, reliable information to you – our readers.
For more information about UTCVM’s Equine Wellness 365 program, visit: https://vetmed.tennessee.edu/vmc/EquineHospital/wellness365/Pages/default.aspx .
The University of Tennessee College of Veterinary Medicine (UTCVM) offered its annual Horse Owners Conference on Saturday March 7, 2020 in the Hollingsworth Auditorium on the UT Ag Campus, Knoxville, Tennessee. The conference offered a range of information on the latest in horse health care from the staff veterinarians, as well as presentations from sponsors Purina, Dechra, and Horsepower Technologies. Even if you have attended this conference previously, there’s always something new to learn from the UTCVM veterinarians and invited guests. The all-day conference provided breakfast and lunch for participants and breaks that allowed opportunities for one-on-one conversations with veterinarians and sponsors. The highly informative event is well worth the modest cost of $10 (early registration) or $20 (late registration).
Conference topics covered a range of horse health issues for both experienced and new owners to learn about their animal inside and out: dentistry, lameness and rehabilitation, emergencies and first aid, nutrition, metabolic syndrome, navicular syndrome and bisphosphonates, laparoscopic procedures, toxic plants, plus mules and donkeys. Dr. Phil Jones, an equine surgery specialist at UTCVM, hosted the conference, introducing each speaker with “punny” jokes in his “slightly” Australian accent that elicited laughter as well as moans and groans. Following is a more in-depth account of the topics.
Common Equine Emergencies & First Aid
The conference began with Dr. Meggan Graves’ presentation on “Common Equine Emergencies & First Aid.” UTCVM provided some “Large Animal Emergency and Critical Care” information sheets to take home: one on how to take your horse’s vital signs; one on colic; one on common equine eye problems; and one on tick-borne disease – equine prioplasmosis, plus a multi-page handout on the Asian Longhorned Tick, which have been shown to carry the causative agents for anaplasmosis, babesiosis, ehrlichiosis, theilerosis, and rickettsiosis, as well as several viruses. These ticks have potential impacts on livestock and wildlife, with the ability to feed in large populations on warm-blooded host animals.
Next, Dr. Melissa Hines gave an “Update on Equine Pituitary Disease and Metabolic Syndrome.” Equine Cushing’s Disease, also known as PPID – pituitary pars intermedia dysfunction, is a disorder of the endocrine system. Cushing’s Disease is caused by enlargement of the pars intermedia of the pituitary gland. Dysfunction of the pars intermedia results in the increased release of several hormones, including ACTH (adrenocorticotropin hormone). ACTH travels through the horse’s blood stream and causes the adrenal glands (located near the kidneys) to increase production of cortisol, a type of steroid. It is this overproduction of cortisol that affects the horse and can explain the majority of clinical signs seen in this condition. Recurrent and often unexplained bouts of laminitis along with an abnormal hair coat are two of the most common clinical signs of a horse with Cushing’s.
Equine Metabolic Syndrome (EMS) describes horses presenting with obesity and/or large regional fat deposits, insulin resistance, and recurrent laminitis. As with Cushing’s Disease, the association between EMS and recurrent laminitis is believed to be a link between the occurrence of insulin resistance and the predisposition for laminitis.
Insulin resistance is a reduction of the horse’s ability to respond appropriately to the hormone insulin, which is involved in the uptake of glucose from the bloodstream following eating and its storage in cells. With insulin resistance, this very important mechanism no longer functions properly. The body tries to counteract its own insensitivity to insulin by producing more and more insulin, and it is the elevated level of insulin that indicates insulin resistance is occurring.
Equine Dentistry: Oral Health Care for Your Horse
Dr. Eric Martin emphasized the importance of routine equine dental care, and began his presentation with an explanation of the horse’s masticatory cycle. Naturally, horses graze 10 – 17 hours per day. Averaging 60 chews per minute, that’s 3600 chews per hour; grazing ten hours a day, that’s 36,000 chews per day, totaling to about 13 million chews a year!
Because of such constant use and wear, a good, thorough dental exam is needed regularly, which should include observing the far back of the mouth, for which the horse may need to be sedated.
The horse’s tooth has an undulating surface, made up of the enamel and cementum, not living tissues, and dentin, which seals and protects the pulp cavity. Horse owners often associate dental care with floating, which simply means to level a surface. Martin emphasized, “Just take off what the horse doesn’t wear down.” Every horse needs a regular good oral exam, which includes an extra-oral exam; evaluation of occlusion, of soft tissue/arcades, of the periodontal structure, and of the endodontic structures of the clinic crown.
What signs can a horse owner observe that indicate dental disease?
· Deviation of the head to one side while chewing
· Quidding (dropping grain or semi-chewed wads of hay/grass)
· Sudden change in mastication pattern
· Bitting problems
· Halitosis (bad breath)
· Excessive fecal fiber length (> ¼ inch)
· Weight loss
· Choke
· Colic
· Avoidance behaviors; change in attitude; facial expression
The horse’s mature dentition occurs at age 5 and they have these teeth for 15 years, on average. Dr. Martin explained the stages of teeth development in horses and the kinds of potential problems that can occur at each age cycle: from birth to 2 years; 2 - 5 years as the adult teeth are coming in (babies don’t have the same number of teeth as adults; horses gain all their molars as adults); and 5- 15 years; 15-25 years, the stage at which changes associated with age become apparent; and over 25 years. This is the end stage of dentition when there is an absence of molar to molar contact, teeth may fall out, and diet considerations are critical. This is where senior feeds are important to give older horses proper nutrition that they can’t get from grazing any more.
He discussed overbites and underbites; wolf teeth (not all wolf teeth cause problems); gingivitis; losing deciduous teeth; caps (deciduous teeth retained); and tartar. “The backyard horse primarily on grass is much less likely to have tooth problems,” Martin explained. It’s chewing the grains and concentrates that wears down teeth faster.
Horses do get cavities, but as the horse’s teeth wear and erupt, the cavities may “take care of themselves. Horses’ teeth are so resilient!” For additional information, link to Dr. Martin’s video on “Equine Dental Care: Beyond Floating” at https://vetmed.tennessee.edu/News/Pages/NewsArticle.aspx?news439 and https://www.youtube.com/watch?v=S7ogc2aR288
Use of Bisphosphonates for Clinical Signs of Navicular Syndrome: OSPHOS® presentation
Following the break, Alex Riddle with Dechra Pharmaceuticals explained their product OSPHOS®, an intramuscular bisphosphonate injection for control of the clinical signs associated with navicular syndrome in horses four years and older. Riddle is from Lexington, Kentucky and his father is an equine veterinarian.
Riddle explained how bones undergo constant turnover, with osteoblasts forming bone and osteoclasts resorbing old bone. In normal bone tissue, there is a balance between bone formation and bone resorption. But in diseased bone, the balance is disrupted. Bisphosphonates inhibit bone resorption by encouraging osteoclasts to undergo cell death, and reduce bone breakdown.
In normal bone remodeling, bone resorption is complete within ~ 3 weeks, but bone formation takes ~3 months. Osteoblast activity and Osteoclast activity are “coupled” to work together, so that the amount of bone formed equals the amount destroyed.
The navicular bone is a tiny bone that sits deep within the hoof at the back junction of the coffin bone and the short pastern bone. On the upper (proximal) aspect of the bone is the collateral sesamoidean ligament, which attaches the navicular bone to the distal end of the short pastern bone. On the lower (distal) aspect of the bone are the impar ligaments, which attach the navicular bone to the coffin bone. Cushioning the navicular bone is a soft serous sac called the navicular bursa.
The navicular bone provides a gliding surface at the point where the deep digital flexor tendon changes angle; the tendon courses down the back of the cannon bone and bends around the back of the fetlock, between the proximal sesamoid bones, then makes a sharp bend over the navicular bone and attaches on the bottom of the coffin bone. Needless to say, this tiny bone bears a lot of load pressure, especially when the horse is doing a lot of work, particularly movement changes.
Riddle explained the chronic intermittent forelimb lameness that is associated with pain arising from the navicular bone and related soft tissue structures. Sometimes this is also called podotrochlear apparatus syndrome or caudal heel pain, and he explained the symptoms.
There are two types of bisphosphonates: nitrogenous and non-nitrogenous. Osphos® is an FDA-approved non-nitrogenous bisphosphonate for use in horses. Non-nitrogenous bisphosphonates inhibit osteoclast recruitment, adhesion, differentiation, and resorptive activity, and induce cell death. Bisphosphonate drugs have the ability to bind to bone mineral and become internalized by osteoclasts. They “stick” to calcium and bind to it. Bisphosphonates are incorporated into the bone mineral and are gradually released over months to years. Navicular syndrome is a bone resorptive condition, i.e., horses with navicular syndrome undergo loss of bone. Dechra states that “treatment with OSPHOS® (clodronate injection) is effective at controlling the clinical signs associated with navicular syndrome in horses 4 years and older.”
Riddle cited the study “Evaluation of the clinical efficacy of OSPHOS® for the control of the clinical signs associated with navicular syndrome in horses,” by Rob Boswell, David Kolb, John Janicek, Stuart Shoemaker, Bradley King, and Michael Frevel. I could not find this study online, but did find a Freedom of Information Summary of this work. Here is the link: https://animaldrugsatfda.fda.gov/adafda/app/search/public/document/downloadFoi/923. The study was done from Jan. 2010 to June 2011.
There are precautions about use and side effects of the drug. Find out more information at www.osphos.com. The product brochure at: http://www.osphos.com/includes/pdf/Dechra-Osphos-Legal-Package-Insert.pdf gives detailed information about the precautions and side effects on page 4.
Editor’s Note: This article “Bisphosphonate use in the horse: what is good and what is not?” (June 2014) by Alexis Mitchell, Ashlee E. Watts, Frank H. ebetino, and Larry J. Suva may be of interest. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6591999/
Ovariectomy and other Laparoscopic Procedures
Dr. Elizabeth Collar, one of the new equine surgeons at UTCVM, explained laparoscopic procedures and showed some videos of what surgeons actually see inside the horse with their tiny cameras.
Laparoscopy is minimally invasive, aka “keyhole,” surgery. Equine surgeons make small incisions, and then insert a camera and surgical instruments to do the procedure. Laparoscopy refers to surgery in the abdomen; thoracoscopy refers to surgery in the chest cavity. While human laparoscopy dates to the early 1900s, equine laparoscopy was first done in the early 1970s, became common in the 1990s, and is the “gold standard” today, she said. The primary laparoscopic procedures used today are ovary removal and internal teste removal. The benefits to this type of surgery are that it minimizes risks and recovery is quicker than with standard surgery that opens up the whole area.
The horse’s “sleep lock” system, or stay apparatus, which allows the horse to sleep standing up, is an advantage for the surgeon who can operate on a standing horse. In the standing position, the surgeon can see the upper (dorsal) abdomen, such as small colon, rectum, spleen, kidney, liver, and lung. If the horse is put under general anesthesia and flipped upside down for surgery, the surgeon can only see what’s in the lower half of the abdomen.
The standing procedure is best for ovary location and removal. Similar reasons for gelding a stallion are given for removing a mare’s ovaries: aggressive behavior, excitable, excessive signs of heat. Ovaries infected with granulose cell tumors, or other pathologies, are also reasons to remove.
Post-op recovery is relatively quick, with discharge a day after surgery, use of NSAIDS and antibiotics, and return to exercise in 3-4 weeks.
Another common laparoscopic procedure is cryptorchidectomy: removing an undescended testicle.
In conclusion, Collar said that elective ovariectomy can improve undesirable behavior in mares. Laparoscopy provides a range of treatment options that are safe, cost effective, and provides diagnostic and treatment opportunities for a variety of other issues.
Equine Nutrition from Purina
Just before lunch, Purina Equine Nutritionist, Anna Pesta, Ph.D. provided information about nutritional support for horses of advancing age. She asked the audience: When does a horse become a senior? Generally, “when the teeth or guts start to go; as soon as the horse can’t keep his body condition as he used to,” and not at a specific age, she said. Senior feeds were developed in 1993 to address an older horse’s decreased utilization of protein, fiber, and phosphorus.
Nutritionally related senior issues include: systemic effects of aging on immunity; over or under weight; poor dentition; and PPID, IR, or EMS. Choose the right feeding program to address these issues.
Immunosenescence refers to the gradual deterioration of the immune system brought on by natural age advancement. Decline in immune function means decreased ability to resist infection, reduced response to vaccinations, and therefore, increased susceptibility to disease. Other signs of aging can include weight loss and decreased body condition, not maintaining muscle mass, or changes in eating behavior. Aging can also affect the senior horse in ways that aren’t always visible, e.g., decline in immune function can affect joint mobility; and chronic low-grade inflammation is also associated with aging.
Purina has partnered with the Gluck Equine Research Center at the University of Kentucky to address these aging issues. Resulting from this research is the inclusion of ActivAge prebiotic in Purina senior feeds. A prebiotic supports the growth of beneficial organisms in the digestive tract, and Purina has developed the specific strain of ActivAge to support immune function in aging horses. Pesta said to think of a prebiotic as “bug food” and a probiotic as the “bug.”
Pesta explained the role of and source of fats in the equine diet, and how to properly feed for weight gain. Most people want to increase fat in the horse’s diet, which is calorie dense and good for coat and hair. But fat alone is not going to increase the BCS quickly, especially in senior horses. Fiber is digested in the hindgut and too much unsaturated fat depresses hindgut digestion. What the horses are missing is digestible fiber calories and may not need more fat. She advised to get better hay, feed more of it, and to consider feeding a senior feed. She said that concentrated calories with a full balance of nutrition produce the best results.
Pesta explained the difference between senior or complete feeds and concentrate feeds. Complete feeds give partial to total forage replacement with a 0.6% body weight (BW) feeding rate. She said it’s not the crude fiber percentage on the feed tag that’s important; it’s the type of fiber. Concentrate feeds are fed with forage at a 0.3% BW feeding rate.
Then she explained the proper nutritional requirements for weight loss. Easy keeper, “efficient,” horses need no unnecessary calories from sugar, starch, and fat, but do need proper protein, vitamins, and minerals levels – especially with reduced forages and grazing. They do need enough fiber for hindgut health. A ration balancer is essential in a diet to reduce weight. And to keep these horses from eating the barn, they do need “eating satisfaction,” so extend their meal time and balance meals with exercise. Pesta gave several weight reduction feed program options.
Next she turned to Insulin Resistant and Cushing’s disease horses. First, get the diagnostics from your veterinarian to determine if the horse has IR or Cushing’s or both. The feed plan will depend on which or both diseases the horse may have.
With insulin resistance, the main objective is to limit starches and sugars in the ration. If the IR horse is easy keeping and/or fat, putting the horse on a lower calorie diet to help them lost weight can actually help improve the insulin numbers. They need moderate quality hay (not free choice) and proper nutrients through a ration balancer. Keep the meal size small with low starch and low sugar in each meal.
Cushing’s horses need a moderate carbohydrate diet and excellent quality nutrition. If they are an easy keeper, a ration balancer can help them. She emphasized, “Don’t starve your Cushing’s horse.” If muscle wasting proceeds, the horse can benefit from a more moderate carbohydrate diet with more calories, e.g., Purina Equine Senior Active. If the horse with Cushing’s is old and not doing well, traditional Purina Equine Senior may be the feed choice for them.
What if your senior horse has a fiber deficiency because they can’t eat hay, or they eat hay but do not get the nutrients from it? Options include a complete senior feed, soaked hay cubes, and beet pulp shreds.
Seniors are more prone to choke, so she went over the causes and ways to minimize this risk.
Finally, she explained how to feed the extremely emaciated, under-nourished horse, which includes an alfalfa re-feeding protocol combined with Equine Senior, and good veterinary care and oversight. But go SLOWLY, she emphasized or you can make their condition worse.
After her talk, Purina generously provided lunch for the conference participants.
Evaluating Lameness
After lunch, it was time for Dr. Phillip Jones to get the spotlight himself, speaking on “Evaluating Lameness: How you can help your veterinarian help your horse.”
He went through the lameness examination procedure to determine the source of lameness in a horse, beginning with an accurate history of the horse. He recommended keeping a diary on your horse.
Beginning with observation of the horse standing, he looks at conformation, for any asymmetries and muscle atrophy, and any evidence of foot problems, such as dragging, hoof/pastern angle, and heel height. “Pay attention to the hind feet,” he said, and explained that each horse has its own “normal.”
He then looks at the horse moving on various surfaces – hard, firm, soft, gravel, sand arenas. Observe at a walk: head movement, placement of feet, do they walk straight, flexion and extension of each joint, cranial (forward) phase of stride (For a hind leg, the cranial phase occurs when the lower leg is under the body of the horse, and the caudal phase is when the limb is out behind the body of the horse), turning both directions, and ear position and general attitude.
Observe at the trot in hand, the horse moving in a straight line, from behind and the sides. Then observe the horse on a lunge line in both directions. He also has a person ride the horse to ascertain the effect of extra weight on the horse. Next come flexion tests.
He emphasized doing a complete physical exam and keeping the order of the body parts consistent when examining the horse. Take videos of the horse and play them in slow motion. Move around the horse and look at it from all sides. Observe how the whole hind end moves together. Then examine the front limb.
When observing the head bobbing that comes with lameness, a good rule of thumb to remember is “down is sound;” the horse’s head bobs down on the sound leg.
He explained that a lot of lamenesses can look the same, so the veterinarian must go through the ordered progression of nerve blocks to properly diagnose lameness.
Jones had a lot of good slides showing asymmetries and slow motion videos to help the audience ascertain which leg was lame.
Donkeys are Different
The tone changed when Dr. Neal Valk came to the podium; “Donkeys are Different” was the title of his presentation. The donkey (Equus africanus asinus) and the mule (Equus mulus) are closely related to, but distinctly different from, the horse (Equus caballus). If you weren’t endeared with donkeys, or respected them, before his presentation, you would afterwards. Owning several of “the world’s greatest donkeys” himself, he has much to praise in these equids.
Dr. Valk pointed out the importance of “looking at the evolutionary history of the animal you’re working with.” Donkeys evolved in north Africa, adapted to a harsh, arid, barren environment. They do not live in herds or bands due to the scarcity of vegetation. Most live solitary lives, coming together only at water sources or during breeding. They have very large ears, which are adapted for hearing over long distances and dissipating heat, and very loud voices for communicating over long distances. Their body and limbs are designed for agility in rough terrain, and are less of a “flight” creature than the horse.
Valk explained: “Donkeys stop first and size up the situation. They are more logical and reasonable than horses and almost totally predictable. Horses can be very unpredictable. Horses move away from pressure, but donkeys move into pressure. And donkeys are very talented at reproducing!”
He gave the baseline TPR for adult donkeys and examples of health care considerations for donkeys. They are susceptible to many of the same diseases that horses are, but appear to be more resistant than horses to some. On the other hand, some horse diseases occur in more severe forms in affected donkeys.
Donkeys tend to have a more “robust” digestive system than horses do.
Donkeys are more “stoic” than horses and are less likely to manifest symptoms of disease until the condition is advanced.
Donkeys appear to tolerate heavy parasite burdens better than horses, even though the parasites are the same between the species. Donkeys are inapparent carriers of lungworms (Dictyocaulus arnfieldii), a parasite which can cause severe respiratory disease in horses.
How to care for you donkey? He recommends administering core vaccines (EWT/WNV and rabies) to donkeys; deworming should be based on fecal egg counts; and regular dental exams and routine dental maintenance.
One of the major health issues he sees in donkeys is obesity. Consider the evolutionary history of donkeys, who are not designed to eat lush grass or concentrates. They are “browsers,” not strict grazers. His recommended diet is 1.2 to 1.5% of the ideal BW of rye or barley straw per day. Yes, straw! Grass hay is too rich and lush pasture should almost always be avoided, as should concentrates. He says his donkeys do well and maintain a healthy body weight living on a semi-dry lot with constant access to medium quality round bales. Fresh water and a salt block are always available.
A common problem for donkeys is hyperlipaemia, a disease caused by too much fat in the blood. To treat/prevent this problem, limit or eliminate access to pasture (but not to forage); avoid high energy feeds; feed hay with <10 to 12% NSC, utilize slow feeders, but DO NOT fast or starve your donkey (results in hyperlipaemia). In addition to the feeding regimen, increase their exercise. He says that track systems work well to reduce access to pasture while providing an enriched environment which stimulates natural movement. In other words, built a track around the perimeter fence and place hay flakes at intervals around the track so that donkeys have to travel to get hay.
Provide browse to your donkeys. Many woody and herbaceous plants are suitable as browse, which satisfies the donkey’s need to chew and provides psychological stimulation. But research the options carefully, as many plants (especially ornamentals) are toxic. One thing he does is to “recycle” Christmas trees as browse for his donkeys.
Finally, routine hoof maintenance/trimming is essential. Donkey hooves are often neglected due to owner misinformation or lack of cooperation on the donkey’s part. Neglect can result in bizarre hoof capsule distortions that cause pain and lameness. Their hooves should be trimmed every 6 to 12 weeks depending on hoof growth rate and environmental conditions. Because of the small stature of many donkeys, trimming can be a challenge, but holding the hooves low and close to the body facilitates hoof care.
Donkeys can founder, which is primarily caused by diet and the high incidence of EMS/insulin resistance in donkeys. PPID is also frequently diagnosed in aged donkeys. Dietary control is the key to successful treatment. However, donkeys do not present founder as horses do, but more likely in decreased movement and more time spent in recumbency, along with elevated digital pulses. Again, diet is the key to management, along with NSAIDs to temporarily relieve pain and correct hoof trimming to improve the mechanics and comfort.
White line disease is endemic in our area and Valk believes it is a manifestation of chronic laminitis. But the disease is very easy to resolve in the donkey, if treated appropriately.
He completed his presentation by debunking “mule myths.” Mules don’t founder (they do). Mules never overeat (wrong). Mules never get arthritis or navicular disease (not true). Mules never colic (not often, but sometimes).
FastTrack™ - Rehabilitative Orthotic
Victoria Boutelle with Horsepower Technologies introduced the FastTrack™ an equine orthotic that actually looks like a brace, which fits on the canon bone and the pastern below the fetlock joint. It is designed to help rehabilitate flexor apparatus soft tissues (tendons and ligaments) which are at risk during extension of the fetlock joint. It supports the fetlock joint and limits movement of the joint, allowing the horse to move while the soft tissues heal.
The device is heated to exactly fit the particular horse, but can be re-heated up to three times to fit other horses. It is sold directly to veterinarians, who can sell or rent the device to their clients. It is only worn for 2 to 3 hours a day, but this allows for the horse to have light exercise as healing is ongoing.
Find more information about this orthotic device at: https://www.horsepowertech.com/
Toxic Plants
Dr. Carla Sommardahl discussed some of the common plants that are toxic to horses. She began with fescue, a grass that is NOT toxic, but may contain a fungus that secrets toxins. There are over 35 million acres in the U.S. that contain this perennial cool season grass, and it is good forage for most horses, especially geldings and non-reproducing mares. The problem lies in the endophyte fungus that can cause problems in pregnant and lactating mares. It contributes to lowered conception rates, prolonged gestations, dystocias (difficult birth), weak foals, stillbirths, thickened placentas, and decreased prolactin levels, which leads to decreased colostrums and milk.
Pasture management can help prevent this situation. Test pastures and hay fields for the fungus, mow fields, remove broodmares from fescue grass and hay at least 30 days prior to breeding and at least 60-90 days prior to foaling. Then keep the mare and foal off fescue until weaning. Dr. Sommardahl said that baling does not kill the toxin and that the fungus likes to live on the fescue seed head.
Red Maple is another plant whose leaves are toxic when wilting. The toxin from red maple affects red blood cells, causes them to rupture and die off, and then the urine becomes red. She said that fresh leaves and autumn leaves that fall on their own are less toxic. The ones to be wary of are those that fall prematurely, such as a broken off branch. The Sugar Maple, which turns orangy in the fall, also has leaves that are toxic, especially spring and summer leaves. Dead fall leaves are less toxic.
Blister beetles build theirnests on the periphery of alfalfa fields, so sometimes the beetles get baled into alfalfa hay. Their bodies contain cantharadin toxin and can usually be found in clusters within bales. It only takes 2-3 beetles to very toxic to horses. Cantharadin toxicity is very irritating to all membranes contacted; the mouth and esophagus can be ulcerated; it can cause colic, kidney damage, and low blood calcium. So only buy certified Blister beetle free hay and inspect each flake before feeding it to your horse.
Crotalaria is a hardy annual with yellow flowers and it is generally not eaten by horses. But if they have nothing else to eat, they may eat it. Senecio is a multi-stemmed annual or perennial with small, daily-like yellow flowers. All parts of both these plants are toxic – fresh or dry. They can cause liver damage, which is cumulative and irreversible. Horses ingesting the toxin get “sleepy staggers” or “walking disease,” which can begin weeks or months after ingestion. They have weight loss and weakness, may show signs of jaundice, and can lead to coma or death.
Aflatoxins are molds that infect seed grains – wheat, corn, oats. Moldy corn contains fumonisin, which can cause brain damage. Monensin toxicity comes from lasolacid growth enhancing feed additives for cattle and poultry. It does not harm cows and poultry, but is toxic to horses. It damages muscles, especially the cardiac muscle.
Heavy metals that are toxic to humans are also toxic to horses, e.g., lead, copper.
Box Elder causes seasonal pasture myopathy, a potentially fatal disease that affects horses’ muscles. Commonly seen in the fall, the disease has been linked to seeds of the box elder tree, a specie of maple that contains hypoglycin A, a toxin.
Rhododendrons, Mountain Laurel, and Azaelas are all beautiful blooming shrubs, but toxic to horses. However, horses don’t really acquire a taste for Rhododendrons.
Oleander (grows in Florida) and Yeware other plants toxic to horses.
Cherry trees and their relatives, even wild cherry, can be toxic. Animals ingesting wilted cherry leaves experience the release of cyanide (HCN) into the bloodstream, a very potent toxin.
Poison hemlock, while it may have beautiful white flower clusters, gives off a bad odor when crushed, and horses rarely eat this plant because of its low palatability. However, poison hemlock plants harvested with hay maintain the toxic properties; so care should be taken to avoid feeding hay containing this plant.
Johnson Grass (Sorghum), Rye Grass, Dallis Grass can contain toxins which cause “staggers,” and can affect cattle, too. Sorghum toxicity causes the horse to lose bladder control. Dr. Sommardahl advised, “Mixed grass hay is better.”
Equine Rehabilitation
Last of the day’s topics was Dr. Karen Shaw’s presentation on “Return to Function: The Focus of Equine Rehabilitation.” Dr. Shaw is an equine sports medicine and rehabilitation resident at UTCVM.
First, what is rehabilitation? The treatment of injury or illness to decrease pain and restore function, and Shaw listed numerous benefits of physical rehabilitation.
From what illnesses/injuries do horses need rehabilitation? Shaw began with osteoarthritis, a bony degenerative condition. The osteoarthritis disease process includes cartilage loss, joint inflammation, subchondral bone change and new bone growth, with joint lining and capsule thickening. Inflammation and pain lead to reduced range of motion.
Treatments for inflammation include corticosteroids, and regenerative medicine therapies such as IRAP, Platelet Rich Plasma, and Pro-Stride.
Her recommended treatment for pain is extracorporeal shockwave therapy.
Then comes improving the reduced range of motion: with stretches, joint mobilizations, and therapeutic exercises – over raised poles and use of leg weights.
She addressed tendon/ligament injury – overloading or strain-induced injury. It begins with the acute inflammatory phase, disruption of the tendon structure. Next is the reparative or fibroblastic phase, the formation of scar tissue, followed by the remodeling phase improvement of fiber alignment and strength.
First, treatment of the swelling and inflammation involves cold therapy, compression, and laser therapy. She showed the use of immersion ice boots, Game Ready full leg wraps, salt water therapy, and laser therapy that stimulates cells and increases cell metabolism.
Regenerative medicine i.e., stem cells, are a treatment protocol for fiber disruption, along with rest and controlled exercise, along with custom orthotic boots such as the Horse Power Fast Track boots. She showed how normal tendon/ligament fibers are arranged in parallel structures, but with injury disruption, the fibers are torn. The stem cell therapy helps re-organize the fibers more like their original parallel structure.
The remodeling phase is a graduated control exercise program that can utilize the underwater treadmill, balance/proprioception training, and acupuncture and chiropractic medicine, which work synergistically.
For muscle conditions/atrophy, that result in weakness, disuse, pain, and muscle dysfunction, therapies for muscle weakness and disuse include electrical muscle stimulation and isometric contractions. To manage pain and dysfunction, acupuncture and chiropractic medicine work hand in hand, along with types of manual therapy like massage, myofascia release, and trigger point therapy. Rapid release technology is often used on scar tissue.
For treatment of wounds, especially those on a joint, therapeutic ultrasound, shockwave therapy, and laser therapy can be used to address scarring and fibrosis issues. The therapeutic ultrasound stimulates fibroblasts and increases cellular metabolism. Therapeutic exercises to improve range of motion include work over raised poles and underwater treadmill.
Dealing with neurological conditions – ataxia, weakness, proprioceptive deficits – utilizes similar exercises as some of the other injuries: proprioceptive re-training with an obstacle course, such as weaving in and out of cones, and balance pads, along with strengthening exercises.
Editor’s Note: I had learned of balance pads, promoted by Wendy Murdoch, but I remained skeptical about their benefit, even as she claimed that her Sure Foot balance pads could address and resolve many of the balance issues that horses incur. After Dr. Shaw’s presentation, I saw the rehabilitative benefit of balance pads to horses with neurologic conditions. Dr. Shaw said they help the horse regain balance and coordination, working on their proprioception.
This 2020 conference provided an abundance of information that covered the horse “from mouth to hoof,” as Dr. Phil Jones explained to the news media. Jones summarized: “What I have seen is that horses around the world are the same. Horses in Australia develop the same conditions as those here in America, and horse owners are the same, as well. Whether their horse is part of a business, an athlete competing in events, or a backyard pet, owners are passionate about their horses because they are part of their family. I grew up with horses myself. Just as with any family member, owners want their horse to be as healthy and as well cared for as possible; they are thirsty for knowledge that would allow them to provide for and care for their horses to the best of their ability. Today everyone has access to all sorts of information on the Internet. So we want to ensure they have access to reliable information, which is why we hosted this conference.” Here at the Mid-South Horse Review, it is our job to pass along factual, reliable information to you – our readers.
For more information about UTCVM’s Equine Wellness 365 program, visit: https://vetmed.tennessee.edu/vmc/EquineHospital/wellness365/Pages/default.aspx .
