Update on Gastric Ulcer Research in Horses

Heather Beach, DVM

In horses, we refer to the generalized syndrome of erosive and ulcerative lesions of the stomach as Equine Gastric Ulcer Syndrome or EGUS. In the last 15+ years since the 3 meter gastroscope has become readily available to practitioners, our understanding of this disease has improved considerably. In September 2015, the European College of Equine Internal Medicine published a consensus statement on gastric ulcers in horses. We now recognize that EGUS should be further classified into two distinct sub-syndromes Equine Squamous Gastric Disease (ESGD), and Equine Glandular Gastric Disease (EGGD).  These two classifications help us to describe the exact anatomical location of the ulcerations, and require specific and distinct treatment and management protocols to ensure proper healing and prevention. 

Normal Margo Plicatus. Squamous epithelium is shown in lighter pink on the left, glandular mucosa is the darker pink on the right. The line between the two is referred to as the margo plicatus.

Normal Margo Plicatus. Squamous epithelium is shown in lighter pink on the left, glandular mucosa is the darker pink on the right. The line between the two is referred to as the margo plicatus.

Equine Squamous Gastric Disease or ESGD 

Equine Squamous Gastric Disease - ulcerations appear as dark red islands along the margo plicatus. The squamous epithelium also has a yellowish color due to chronic irritation and fibrin production within the stomach.

Equine Squamous Gastric Disease - ulcerations appear as dark red islands along the margo plicatus. The squamous epithelium also has a yellowish color due to chronic irritation and fibrin production within the stomach.

Equine squamous gastric disease (or ESGD) is the form of gastric ulcers that most people are familiar with. The stomach of the horse is anatomically unique -- the top portion is covered in a lighter squamous epithelium, while the bottom is composed of darker glandular portion. The cells lining the squamous portion of the equine stomach are similar to skin cells and the cells that line the esophagus. These squamous epithelial cells have no protection against the harsh pH of stomach acid, which typically pools lower in the glandular portion of the stomach. The cells in the glandular portion of the stomach secrete bicarbonate and mucous which offer protection against the harsh, acidic environment. When a horse exercises, the acid from the lower portion of the stomach splashes against the squamous epithelium and can cause ulcerations, frequently noted at the anatomical delineation between non-glandular and glandular portions of the stomach, known as the margo plicatus.

Treatment for Gastric Ulcers in the Horse (ESGD)

ESGD is treated by suppressing acid production in the horse for a minimum of 21-28 days. The best studied product for achieving acid suppression and healing of ulcerations is the medication ompeprazole, sold under the brand name of GastroGard. Near the end of the first month of treatment, a recheck gastroscopy is recommended to ensure the ulcerations have healed, because as many as 25% of horses may require longer than 28 days of treatment. 

Equine Glandular Gastric Disease (EGDD)

EGGD differs from ESGD, in that it is believed to result from a breakdown of the normal defense mechanisms that protect the mucosa from acidic gastric contents, since this portion of the stomach is normally subjected to near constant exposure to acid. The factors that contribute to breakdown of this protective layer are yet to be clearly demonstrated in the horse, but in humans the bacteria Helicobacter pylori and the use of non-steroidal anti-inflammatory drugs (NSAIDs) are most common causes of gastric ulcers. To date there remains conflict in the literature as to the role of bacteria in EGGD. While the prolonged use of NSAID medications in horses such as Bute or Banamaine may play a role in causing EGGD, many horses who have not received these medications still suffer from this disease. It is likely that multiple different mechanisms contribute to the development of EGGD in the horse. Reduced access to water has been shown to increase the prevalence of both EGGD and ESGD in horses.

Normal appearance of glandular mucosa at the level of the pyloric outflow tract. This is the part of the stomach that leads to the beginning of the small intestines.

Normal appearance of glandular mucosa at the level of the pyloric outflow tract. This is the part of the stomach that leads to the beginning of the small intestines.

Equine Glandular Gastric Disease - a large ulcerated area of the glandular mucosa at the level of the pyloris.

Equine Glandular Gastric Disease - a large ulcerated area of the glandular mucosa at the level of the pyloris.

Treatment for Equine Glandular Gastric Disease (EGDD)

Treatment of EGGD is not as straightforward as treatment for ESGD. In most cases, omeprazole alone is not sufficient to heal EGGD ulcerations. Other medications utilized along with omeprazole to heal lesions in this region of the stomach include:

  • Misoprostol - this is a synthetic prostaglandin thought to help restore some of the body's natural defenses against acid by providing additional acid suppression, increased mucosal blood flow and increased bicarbonate secretion.

  • Sucralfate -  This is a medication that binds to the negatively charged particles in the ulcer bed, buffering acid by increasing bicarbonate secretion, stimulating prostaglandin production, and coating the ulcer bed. In the stomach, sucralfate is converted to a sticky amorphous mass, which is thought to prevent diffusion of acid into the ulcer.

SYMPTOMS OF GASTRIC ULCERS IN THE HORSE

Gastric ulcers in horses can lead to pain and discomfort, poor performance and colic. Symptoms of gastric ulcers vary and may include:

  • Behavior changes: varying from crabbiness to explosiveness to nervousness
  • Girthiness: or generalized reluctance to be groomed or touched
  • Poor performance: symptoms may mimic or overlap with symptoms of back pain and include reluctance to lift through the back, difficulty cantering, sour attitude towards work
  • Poor appetite: picky eating, bolting food then walking away from grain bucket
  • Poor body condition/weight loss
  • Chronic diarrhea
  • Poor coat condition
  • Grinding teeth
  • Stereotypical behaviors: cribbing, weaving, stall walking

If your horse is showing symptoms of gastric ulcers, getting a definitive diagnosis through gastroscopy before and after treatment is the best way to ensure an accurate diagnosis and successful course of treatment. 

How to Recognize, Treat & Prevent Back Pain in the Horse

Heather Beach, DVM

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Back pain is a common finding in performance horses. While back pain can be a challenge to definitively diagnose, there are many treatment and physical therapy strategies available to help strengthen your horse's spine and increase comfort and performance. 

Symptoms of Back Pain

Back pain in horses can present with a variety of symptoms. Some of the more common symptoms include:

  • Poor performance/reduced performance which may progress to behavioral problems (rearing/bucking/stopping or running out at fences). Many horses will feel "disconnected" from front to back, or may have a short strided gait in general. 
  • Discomfort to grooming or pressure over the back. This should be interpreted with caution because some horses may simply be "thin skinned" and may not be experiencing significant back pain. A sudden change in your horse's response to grooming may be an indicator of back pain however. 
  • Resistance to saddling, increased "girthiness" or abnormal gait after being saddled.  
  • Remember, some horses are very stoic! Many will still perform well yet still show evidence of significant back pain on clinical examination. A careful examination of the back should be part of any lameness/soundness evaluation and can be checked even in the absence of performance problems. 

Anatomical Considerations

Understanding the anatomy of the horse's back is the first step to managing equine back pain. There are two distinct muscle groups to consider when treating the horse's back: the longissimus muscles as well as the multifidus muscles.

The longissimus muscles are the external back muscles that we see when we evaluate a horse's topline. These muscles often palpate sore, and show spasm and external signs of discomfort. The longissimus muscles run the entire length of the horse's back and as such can easily get fatigued and sore if they are asked to support and stabilize the entire spine on their own.

Deeper within the spine however, the multifidus muscle is found. This muscle forms attachments between the individual vertebrae. Each segment of this muscle is short and controls only a few vertebrae and the joints between them. Since every segment of this muscle is shorter than the longissimus muscle system, it does a much more effective job of stabilizing and supporting the spine. If the multifidus muscle is too weak and ineffective at stabilizing the spine, the longissimus muscles will work harder to compensate, leading to pain and spasm in the external muscles of the back.

Our goals when treating back pain are to:

  • Rule out and treat primary pathology in the back (kissing spines, arthritis between the joints, ligament damage etc.)
  •  Treat the pain and spasm of the longissimus muscles
  • Provide physiotherapy and exercises to recruit and strengthen the multifidus muscles so that the horse can maintain his back pain-free going forward

Diagnosing Primary Back Problems

Radiographs and ultrasound can be performed on the farm to assess the horse for primary back problems. In some instances, a bone scan might be recommended if the case is complicated or not responding as predicted. 

Moderate to severe kissing spine lesions. There are over-riding dorsal spinous processes with active bony lysis at the sites of impingement.

Moderate to severe kissing spine lesions. There are over-riding dorsal spinous processes with active bony lysis at the sites of impingement.

Besides kissing spine lesions, other primary back problems include injuries to the ligaments of the back, including the supraspinous ligament and the dorsal sacroiliac ligaments. Horses may also have arthritis of the joints or "facets" of the spine. These conditions are best imaged with ultrasound, but often times are brought to our attention following a bone scan that shows active bony turnover in these regions. Treatment for primary back pain depends on the problem found and may include:

  • Injections of anti-inflammatory medications +/- shockwave therapy around the sites of kissing spine lesions
  • Bisphosphonates such as Tildren or Os Phos
  • Thoracolumbar facet injections in the case of joint arthritis
  • Rest, shockwave or regenerative therapies in the case of soft tissue injuries

In most cases of primary back pain, there will still be pain and spasm of the surrounding longissimus muscles that will also benefit from treatment.

Treating Back Pain and Muscle Spasm 

When we treat the pain and spasm of the longissimus muscles, we are often erasing the symptoms of another problem. Treatment is typically highly effective, but without addressing the underlying reason for the back pain, the effects will only be temporary. Back pain and muscle spasm can result from:

  • Primary back pathology as noted above
  • Lameness elsewhere in the horse, especially hindlimb lameness
  • Poor saddle fit
  • Unbalanced riders
  • Bracing secondary to gastric ulcers
  • Instability of the spine due to weakness of multifidus muscles

Treatment modalities for pain and spasm of the longissimus muscles include:

  • Direct injection of anti-inflammatory medications into the back muscles
  • Mesotherapy
  • Shockwave Therapy
  • FES Therapy (Functional Electrical Stimulation)
  • NSAIDs (bute, banamine, previcox)
  • Muscle relaxants -- Robaxin
  • Alternative medicine - chiropractic and acupuncture treatments

Strengthening the Back

Following treatment for back pain, it is crucial that the horse begin working properly and engaging in targeted physiotherapy to strengthen the stabilizing muscles in order to achieve lasting results. If the horse and rider team are experienced, this can be achieved through consistent work under saddle with proper riding technique that encourages the horse to lift through the back and engage the core muscles. In some instances, the use of properly applied training aids on the longe line can be beneficial.

Functional electrical stimulation (FES) therapy is a very effective treatment for strengthening all the muscles of the back. FES therapy can also effectively treat muscle spasm and help restore symmetry to the horses muscles when one side has become over or under developed. 

Carrot stretches, or "dynamic mobilization" are another proven physiotherapy approach to strengthening the mutifidus muscles of the horse's back. In this article by Dr. Hillary Clayton, the correct method for performing carrot stretches is shown with easy to follow photos and explanations of the technique. 

For some horses, back pain is a recurring problem that requires maintenance and attention on a regular basis. For other horses, breaking the pain cycle and allowing them to use themselves properly will mean that their ongoing maintenance is minimal. 

 

 

 

 

    Electrolyte Supplementation in the Horse

    Sweating the Small Stuff -- Electrolyte Supplementation in Horses

    Heather Beach, DVM

    Now that we are getting into the hot summer months, many horse owners will instinctively reach for their tubs of electrolytes and start adding them scoop by scoop to their horse’s grain.  If you have fed electrolytes in summer before but are sitting there secretly wondering inside your head, “what are electrolytes anyway? Why exactly do I give them to my horse? When am I even supposed to give them?” you are definitely not alone.  Electrolytes are probably the most frequently administered feed additive that barely anyone in the horse world knows anything about.  

    So what are electrolytes anyway?  

    Essentially, electrolytes are the minerals and salts that circulate within the bloodstream and tissues of the body.  Sodium, potassium, calcium, magnesium, and bicarbonate are some of the most important ones found in the body.  These substances are abbreviated by their chemical name and also the “electric charge” they carry relative to one another.  So Sodium = Na2+, Potassium = K+, Chloride = Cl-,Calcium = Ca2+, Magnesium = Mg2+, and Bicarbonate = HC03-.  Proper concentrations of these electrolytes in the bloodstream and muscle tissues are essential for life and basic body functions.  

    So, if I don’t feed electrolytes, my horse will die?  

    Not exactly, but maybe.  The body is extremely good at maintaining normal levels of electrolytes in the blood stream.  It takes major disease processes or major electrolyte losses for the body to lose its ability to keep the levels in a normal range.  Under most normal circumstances, electrolyte supplementation is not necessary as a daily additive. 
     

    So I can throw away my tub of electrolytes?  

    Definitely no.  Both horses and humans lose a great deal of water through the action of sweating.  This is the purpose of sweating -- the water wets the skin and then evaporates as the air touches it, creating a cooling effect for the body.  This is why cooling is more difficult in humid weather, as sweat evaporates less efficiently.  What is unique about horses is the fact that they lose a tremendous amount of Sodium (Na2+) and Chloride (Cl-) in their sweat as well as smaller amounts of Calcium (Ca2+) and Potassium (K+).  This is why horse sweat gets so frothy sometimes -- the lather is caused by all the salts present in equine sweat. That's where your electrolytes are going!  So if your horse engages in strenuous activity especially in hot humid weather, and especially if he is going to be asked to repeat that activity in a short amount of time, you should be giving supplemental electrolytes.  For extremely demanding activities such as endurance racing or cross country, electrolytes should be administered before, during and after the stressful event.

    What else should I know about electrolytes?

    Electrolyte supplementation can help prevent dehydration during times of high sweating. Thirst is stimulated by increasing sodium (Na2+) concentration in the blood stream. Human sweat is much closer to plain water, so as water leaves our blood stream in the form of sweat, sodium stays behind, blood becomes saltier, brains says "Ah!! Thirsty! Drink more water!"

    The horse on the other hand pulls yet another move from the "designed to die" playbook. The horse sweats water AND high concentrations of electrolytes, so as the horse loses more and more sodium and other electrolytes through sweat, it actually becomes LESS AND LESS THIRSTY which leads to dehydration then impaction colic if you're lucky; tying up, renal failure and death if you're really unlucky, or if you just keep giving it banamine relentlessly instead of calling a veterinarian for help. Horses who have become electrolyte depleted may have an elevated body temperature and heart rate, show signs of muscle cramping or tying up, exhaustion, lethargy and/or depression. An exhausted horse who is electrolyte depleted is a medical emergency and will require intravenous fluid replacement therapy as soon as possible. 

    Horses can also lose so much calcium through their sweat that they develop a condition known as "Synchronous Diaphragmatic Flutter" aka "thumps." The horse will appear to have the hiccups with this condition and it is a sign of extreme electrolyte derangement and requires immediate treatment. You would think that lots of oral calcium supplementation would help prevent this, but sadly ... this is not true. Too much oral calcium for too long leading up to a stressful event (endurance race, cross country) can actually predispose a horse to getting the thumps by activating a hormone in the gut and kidneys that signals the body to excrete excess calcium instead of storing it in the bones. So it is best to keep calcium supplementation to just before an anticipated time of loss. 

    What do I look for when buying electrolyes?

    Dr. Jeannie Waldron, an equine veterinarian and endurance race rider, wrote a great article on this topic in Practical Horseman Magazine. She recommends the following:

    • Check the label carefully. Look for chloride and/or acetate combinations such as sodium chloride, calcium chloride or calcium acetate, potassium chloride; these are quickly and easily absorbed. Avoid products that use di-calcium phosphate (which horses don't absorb very well) and those that list sugar, dextrose or corn syrup as the first ingredient.

    • Important: Electrolytes containing bicarbonate are formulated for horses with diarrhea. These can be harmful when used as an electrolyte supplement for stress and exercise.

    • If you need to supplement your horse's electrolytes and commercial products are unavailable, it's possible to make homemade electrolytes by combining "lite" salt (an excellent source of potassium and chloride) with sources of calcium and magnesium such as Tums. However, these formulas aren't absorbed as well as the commercial ones.

    Dr. Jeannie Waldron recommends the product Endura Max electrolytes for her horses when out on the trail or endurance racing. I personally use KER's Summer Games Electrolytes which does contain di-calcium phosphate, but I am not concerned about extreme calcium depletion as my horse is not eventing or doing endurance racing. Electrolyte supplementation for horses in those disciplines should be carefully fine tuned and is beyond the scope of this article!

    Stay cool and hydrated everyone!