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Reading between the Lines: White Line Disease
What is it?
White line disease (WLD), is a multifactorial process that leads to a progressive separation of the inner zone of the hoof wall. The white line of the hoof can be visualized on the sole, and is the junction of the insensitive laminae of the hoof wall and the horn of the sole. The hoof wall consists of three layers: the stratum externum (external layer), stratum medium (middle layer), and stratum internum (inner layer). In WLD, the hoof wall separates from the underlying laminae (stratum internum) at the level of the stratum medium, also known as the tubular horn. When we use the term "white line disease", we are referring to the fact that the horse has some degree of separation of the hoof wall from its laminar attachments. Typically, the condition begins with a crack or opening within the white line, which then allows bacteria or fungus to enter the stratum medium. Since this is closely associated with the laminae, cavities subsequently develop between the laminae and outer hoof wall.
What causes it?
White line disease can affect a horse of any sex, age or breed, barefoot or shod. Mechanical stress, inappropriate farriery, genetic factors, and environmental conditions may all play a role in the development of WLD. Poor hoof hygiene has often been held responsible for the development of WLD, however it remains questionable as the initiating cause. It is believed that the primary event is mechanical stress on the inner hoof wall such as from poor hoof conformation or less than ideal farriery. These include, excessive toe length, poor hoof conformation, and various hoof capsule distortions such as long toe-under run heel, clubfoot, or sheared heels. This stress leads to breakdown of the hoof's natural barrier, and allows invasion of opportunistic bacteria that possess keratinolytic enzymes. These bacteria digest the hoof horn, leading to the progression of the separation proximally towards the coronet band. If left untreated WLD will become extensive and displacement of the distal phalanx can become a sequel.
How do we diagnose it?
Clinical signs for WLD can vary and the degree of lameness present can range from non-existent to severe. Some horses may show a positive reaction to hoof testers while others may not. This is why it is very important to start the diagnostic process with a thorough physical exam and lameness evaluation. As WLD becomes moderate to severe, damage is sufficient to allow mechanical loss of the attachment between the laminae and the inner hoof wall, clinical signs of pain (typically lameness) can be seen. When examining the foot from the solar surface, there is often a visual confirmation of a separation between the hoof wall and underlying laminae. Looking even deeper into the inner hoof wall, the inner white line will typically show a separation filled with a grey/white powdered horn material. A probe can be used to further explore the depth and extent of the cavitation. Additionally, a hollow sound is typically heard if the outer hoof wall is percussed with a hammer. WLD should be differentiated from other common foot lameness that will block out to a palmar digital block, such as chronic laminitis and foot abscesses. If lameness is present on initial evaluation, a thorough lameness examination should be performed including nerve blocks to confirm the suspected area followed by radiographs. When extensive hoof wall damage is present and subsequently pain, WLD can mimic laminitis both clinically and radiographically, and thus it is important to differentiate between the two.
Radiographs should be taken to show the extent of separation between the hoof wall as well as to rule out laminitis. A lateral and dorsopalmar view are generally sufficient to allow for accurate interpretation of WLD. In chronic cases of WLD, pedal osteitis has been seen as a sequelae. Radiographs also allow for better visualization of the hoof capsule and can help with trimming and shoeing the horse in the future.
How do we treat it?
When treating WLD, corrective trimming is imperative to remove abnormal stresses on the hoof wall, in conjunction with resection and debridement of the entire extent of the separated hoof wall until the firm, healthy adhesion of the hoof wall to the underlying stratum internum can be seen. Resection of the hoof wall is performed using hoof nippers, a hoof knife, and motorized tools.
Adjunctive shoeing techniques are then applied to provide adequate support to the remaining foot and to remove stress from the affected part of the foot. A heart bar or egg bar shoe redistributes weight-bearing forces to the frog and palmar region of the foot and away from those damaged and therefore weakened areas. Resilient putty is typically used in conjunction with shoe to provide distal phalanx support, especially if displacement of P3 (coffin bone) is a concern. Additionally, it is important that the hoof remains clean and dry. The horse must be kept in a dry stall after treatment, and drying agents (ie. iodine) can be applied to the resected area to prevent excessive moisture from building up. The affected hoof should be cleaned daily with a wire brush. Systemic medical therapy is not required in conjunction with the resection since this disease is limited to the keratinized area of the hoof wall. Plastic acrylic repair may be used as well for prosthetic hoof wall repair, as depicted in Figure 4.
Figure 4: Acrylic hoof wall repair
Prognosis is dependent on the response to treatment, as well as the effect of the original insult. Horses with poor hoof quality or primary laminitis tend to have reoccurrences of the disease. If initial response to treatment is good and proper environmental conditions exist, then the prognosis is better.
For any other questions associated with white line disease, please feel free to call New England Equine Medical & Surgical Center, or discuss management strategies with your local farrier.
Jordan E. Koivu, DVM
Elizabeth Taylor, DVM, DACVS - LA
"White Line Disease in Horses." Lameness in Horses: Merck Veterinary Manual. 1 Sept. 2015. Web. 10 Dec. 2015.
O'Grady, Stephen E. "Management of White Line Disease." Equine Podiatry. 2006. Web. 10 Dec. 2015.
Ross, Mike W., and Sue J. Dyson. "The Foot: Trauma to the Sole and Wall." Diagnosis and Management of Lameness in the Horse. 2nd ed. St. Louis, Mo.: Elsevier/Saunders, 2011. Print.
Recurrent Airway Obstruction (Heaves)
Horses are active and athletic animals that need to breathe efficiently and effectively to perform to their full potential. Respiratory problems can often go unnoticed, especially in the early stages, due to subtle or mild signs. The main signs of illness horse owners are advised to watch for such as fever, depression, or going off feed are not always present. Recurrent Airway Obstruction (RAO, "heaves") is a respiratory disease that is often overlooked in the early stages.
Recurrent airway obstruction is an allergic airway disease characterized by a chronic cough, nasal discharge, weight loss, and respiratory impairment that ranges from exercise intolerance to respiratory distress while at rest. Affected horses are typically middle-aged to older and do not show other signs of illness such as fever, depression, or pain. There have been two forms of RAO described: one is associated with exposure to irritants commonly encountered with confinement housing such as from dust, hay and bedding. The other is associated with molds growing on pastures in the summer. RAO is a common non-infectious inflammatory pulmonary disease that impacts the health and performance of horses across all equine disciplines.
Clinical signs occur in susceptible horses that are exposed to inhaled allergens from dust, mold spores and particles released by hay and bedding (straw bedding). When exposed to these allergens the horse's body responds by closing the airways (bronchoconstriction) and increasing bloodflow and cellular exudate resulting in inflammation and mucus production to trap the allergens and facilitate clearance. These mechanisms are meant to be protective of the airway but the result is detrimental to the horse's respiratory function. The bronchoconstriction and excess mucous increases the resistance to airflow especially during expiration. The increased expiratory pressure requires recruitment of the abdominal muscles to aid in exhalation. This results in well-developed abdominal muscles (hypertrophy of the external abdominal oblique muscle which gives the characteristic "heave line" appearance. The increased respiratory effort leads to decreased feed intake which results in weight loss. Horses with RAO tend to be exercise, heat, and humidity intolerant.
Continuous and prolonged irritation and inflammation of the airways increases their sensitivity resulting in exaggerated responses to the irritation, further exacerbating the problem. The respiratory tract's barrier defense is weakened and lead to secondary bacterial infections. Chronic infections lead to scarring of the lower airways further restricting the elasticity of the lung tissue and increasing the respiratory effort.
Recurrent airway obstruction is diagnosed based on clinical signs and by ruling out other causes of respiratory disease. A chronic cough, and nasal discharge without a fever are characteristic of RAO. An expiratory wheeze may be auscultated by your veterinarian on physical exam. Labwork typically shows a normal complete blood count, fibrinogen, and serum chemistry unless a secondary infection or concurrent disease is present. A Bronchoalveolar Lavage (BAL) is performed to evaluate cellular infiltrate, of which 35-50% of cells are expected to be neutrophils in horses with RAO. Spiral shaped mucous plugs from small airways (known as Curshmann's spirals) may also be seen. Transtracheal Wash (TTW) may be performed to obtain a sample for culture prior to a BAL in cases suspected of bacterial infection. Yellow exudate of increased viscosity may be visualized in the trachea via endoscopic exam. Radiographs may reveal over-expanded lung fields and peribronchial pattern of infiltrates while ruling out other lung disease (interstitial pneumonia, neoplasia, and abscess). Ultrasonographic evaluation of the lungs may also be used to assess the lungs and rule out concurrent disease.
Horses in respiratory distress need immediate veterinary intervention. Severe cases are treated with systemic corticosteroids and bronchodilators. While very effective, the potential complications (laminitis, adrenal suppression, decreased gastrointestinal motility, colic, etc) of these medications preclude their use as long-term therapies. Medical management with anti-inflammatories and inhaled bronchodilators are short term therapies to be used until the respiratory tract returns to a healthy state and environmental adjustments can be made.
The most important treatment and prevention of RAO is long-term environmental management. Affected horses should be kept on pasture at all times. A three sided run-in shelter may be provided for protection from inclement weather. Dry lots and enclosed confinement should be avoided. Prior to feeding, hay is to be closely inspected for signs of mold and soaked in water to remove dust and particulate allergens. Alternatively the horse's diet may be changed to a pelleted complete feed or fed bagged hay with high moisture content. Horses with the summer-pasture associated RAO respond best to stall confinement during the summer months when molds are growing on pastures. For horses that must be confined to a stall, stable management should be a priority. Hay should be stored in a separate building from where the horse is stabled, and never above the stall. Stalls should be well ventilated and cleaned daily, kept free of dust, cobwebs, and loose feed, and the horse should be removed during cleaning when the air concentration of particulate matter is highest. Additional measures such as using hypoallergenic bedding and watering arena footing can help to minimize dust and RAO irritation.
Early diagnosis and intervention is essential to prevent the disease from reaching an irreversible state. Recurrent airway obstruction is not curable, but it can be well managed through appropriate environmental changes. Horse owners and barn managers play an important role in the prevention and treatment of this disease.
Doctor Joslyn Mumford
Equine Colic: More than just a bellyache
It’s colic season!! Or so it seems that way in New England.
Colic, a term that simply means “abdominal pain”, is anything but simple when it comes to horses. Colic is one of the leading causes of premature death in horses and the number one emergency for equine veterinarians. Whether the clinical signs are obvious or very subtle, the sooner that you realize your horse is colicking, the better the prognosis will be.
Continue reading below for ten important things to remember when your horse is colicking on the farm as well as ways to decrease the risk of colic.
1) >Clinical signs of colic can vary immensely, depending on the horse, their pain tolerance, and the type of colic that they are experiencing. Some horses may exhibit multiple clinical signs, while others may only show one or two. Here are some clinical signs to watch out for that could mean your horse is colicking:>
- >Loss of appetite>
- >Flank watching (turning of the head to look at the abdomen)>
- >Biting at sides>
- >Straining to urinate>
- >Getting up and down repetitively>
- >Decreased fecal output or diarrhea>
- >Increased respiratory rate>
- >Increased or decreased gastrointestinal sounds>
2) >Check your horse’s vital signs. Try to get a heart rate or pulse rate, either by using a stethoscope to listen directly to the heart (just behind the elbow of the front left leg, under the shoulder) or get a pulse rate by feeling the facial artery underneath the horse’s jaw. A normal heart rate for most horses is between 28 and 44 beats per minute. If the heart rate is above 44 beats per minute, it is elevated and could be due to pain. Grab a thermometer and check to see if the horse has a fever – a normal rectal temperature should be between 99F and 101.5F. Take your horse’s respiratory rate, which should be between 12 and 20 breaths per minute. Check to see if there is any manure present in the horse’s stall or paddock, and if so is it normal consistency, dry or diarrhea.
3) >Call your veterinarian as soon as you are suspicious that your horse is colicking. Whether the clinical signs are severe or very subtle, waiting too long could allow small problems to become critical and critical problems to become untreatable. Describe your horse’s behavior to your veterinarian, and let them know the vital parameters if you were able to obtain them. It can also be beneficial to let your veterinarian know if the horse has a history of colic. Lastly, let them know if feces were present in the stall and if the horse has been eating and drinking normally. With this information, your veterinarian can better assess the horse over the phone as well as the severity of the colic.>
4) >While you are waiting for your vet to arrive, make sure your horse is not rolling, pacing or thrashing, as this can lead to further injury. Hand walk the horse if they continue to roll or thrash in a stall. If the horse will lie down quietly, without rolling or constantly getting up and down, this is okay. Sometimes, it is easier for gas to be passed when they are recumbent. Check on your horse every 15 minutes. Colics can progress rapidly in some circumstances and need to be closely monitored so that any deteriorating condition can be treated promptly.>
5) >Restrict access to any feed while you are waiting for your vet. Food can often make the existing problem worse, even though some horses still have an appetite when they colic. It is also important to limit any water intake until a veterinarian has passed a nasogastric tube to check for additional fluid (reflux) causing distension of the stomach. Excess water could lead to a ruptured stomach.>
6) >You should talk with your veterinarian over the phone before medicating the horse, since anti-inflammatories, analgesics and sedatives can mask clinical signs, which can make it more difficult for the veterinarian to properly diagnose the severity of the colic. If the horse is very painful and needs medication immediately before the vet can arrive, be careful not to overmedicate. Banamine® (flunixin meglumine) should only need to be given once every 12 to 24 hours. If banamine is not decreasing the horse’s level of pain, then the horse needs stronger pain medications and potentially medical or surgical treatment.>
7) >Whenever your horse is colicking, it is important to keep in mind whether the horse has the option of going to a referral center for further medical or surgical treatment. The sooner the horse is treated medically or surgically, the better the prognosis will generally be. Financial concerns play a huge role in this decision and so it is important to think about this before an emergency actually occurs. A medical colic that requires IV fluid therapy can cost up to $5000 and surgical colics can range from $5000 to over $15000 depending on complexity and postoperative complications. If you have an insurance plan, make sure you know beforehand how much your company will contribute.>
8) >Once you decide that the horse can no longer be medically managed at the farm and you would like to take it to a referral center, start to plan for transportation. Do you own a trailer or will you have to call a shipper? It is important to have a trailering plan in place before an emergency occurs so that time is not wasted trying to find a ride. If it is possible for the horse to be shipped in a box stall, or to remove the partition in a smaller trailer, this is best in case the horse goes down on the way to the referral center and becomes trapped between the divider. Never travel in the trailer with a colicking horse, as this can quickly become dangerous for the passenger. >
9) >Many colics occur due to changes in frequency of feeding, type of feed or hay, or decreased water intake. It is best to feed smaller amounts of feed more frequently throughout the day if this is possible. Any changes to your horse’s feed should be made very gradually over 10 to 14 days. Forage should always be the main component of a horse’s diet unless special circumstances discussed with your veterinarian state otherwise. Finally, always monitor your horse’s water intake and be sure to encourage them to drink as much as possible. This is especially helpful with preventing impactions. Whether this means adding some water to their grain, or putting out an extra water bucket with some electrolytes, it is important to take extra steps to ensure that they are staying hydrated.>
10) > Management strategies, such as effective deworming protocols, gastric ulcer prevention, and regular exercise all play a role in maintaining a healthy horse with a lower risk of colic. Always refrain from giving medications unless instructed by your veterinarian, since NSAIDs, such as Bute® (phenylbutazone) or Banamine® (flunixin meglumine), can cause gastric ulceration, and antibiotics can disrupt the natural microflora of the gut and predispose to colitis.>
Colic can be a scary condition when it happens to your horse, but taking steps to prevent it and being prepared to deal with it can certainly help everyone remain calm in the incidence that it does occur.
If you have any questions regarding this article, or the treatment and prevention of colic, please contact your veterinarian or the doctors at New England Equine Medical & Surgical Center.
Jordan E. Koivu, DVM
New England Equine Medical & Surgical Center, 15 Members way, Dover, NH 03820
My Horse has a Cough. Now What?
Lori Smolkovich, DVM
As a horse owner, it is often a clear decision as to whether your horse needs veterinary care. Examples include lameness, colic, choke, etc. But what do you do when your horse shows signs that are more vague, like a cough. It could be a mild irritation, or it could be indicative of an underlying condition that needs treatment. How do you decide? In this article, cough, some of the causes of cough, and treatment will be discussed. Hopefully this article will allow you as a horse owner to be able to make a more educated decision as to when a cough requires veterinary care, help you be prepared for some of the questions your veterinarian will ask you, and allow you to better understand why certain questions are being asked and why some tests are necessary to perform.
There are dozens of reasons why your horse could be coughing. So the best place to start is by determining whether or not your horse has a fever. Take your horse's temperature once or twice a day for several days. If the temperature is higher than 101.5 F your veterinarian should be contacted. A cough with a fever is often indicative of an infectious or neoplastic condition and warrants veterinary care immediately.
If your horse is not febrile, take notice of your horse's environment, times that he coughs, and whether he shows any other clinical signs. This will allow your veterinarian to have more insight as to what may be going on. Does your horse cough more in one season than the others? Does your horse cough when he is in his stall or outside in turnout? Does he cough when he is eating? During/after he has been exercised? Does he have nasal discharge? If so is it coming from one or both nostrils? Is the discharge clear, yellowish, bloody, etc?
The first thing your veterinarian will do to assess the cough, is a thorough physical exam. If an arrhythmia is ausculted (heard through a stethoscope), a cardiac ultrasound may be warranted. This is because if the heart is not able to adequately pump blood forward as a result of a heart condition, fluid can accumulate in the lungs, causing a cough. If respiratory noises can be ausculted in the lungs of your horse, a transtracheal wash (TTW) or a broncheoalveolar lavage (BAL) are warranted. These tests are different, and depending on what your veterinarian suspects is the problem, will decide which test is appropriate. A TTW is very useful for identifying infection such as a bacterial or viral pneumonia. A BAL is very useful if an infection is less likely and a condition such as Inflammatory Airway Disease (IAD), Recurrent Airway Obstruction (RAO) or pleural effusion is suspected. Both of these tests allow a sample of fluid to be collected. By analyzing the cells in the sample, your horse's condition can likely be diagnosed.
Ultrasound is a great modality to allow us to gather more information about the lungs. Even if no abnormal lung sounds can be ausculted, it is possible diseased lung is still present, it has just not progressed far enough for abnormal lung sounds to be detected. Thoracic ultrasound allows us to visualize the lungs and determine whether there is consolidation (deflated lung that is no longer able to participate in oxygen exchange), fluid in the lungs, pleuritis, pleuropneumonia, etc. Also, if there is fluid in the chest (pleural effusion), ultrasound allows us to choose the most accurate location for thoracocentesis (collection of lung fluid for analysis), which will in turn provide more information.
In working up and evaluating a horse with a cough, an endoscopy is warranted. During an endoscopy, a camera is used to visualize the trachea, upper airways and the guttural pouches. The endoscopy allows us to diagnose many conditions of the upper airway that can cause a cough. Examples include anatomic defects that result in the airway not being appropriately protected from debris, resulting in a cough, such as dorsal displacement of the soft palate, rostral placement of the palatopharyngeal arch, arytenoepiglottic fold entrapment, and subepiglottic cysts. Other conditions that can cause a cough, such as tracheal collapse, partial obstruction of the trachea, either by a foreign body or a mass can be visualized on endoscopy. Finally, the guttural pouches can also be inspected for conditions such as empyema (pus in the guttural pouches), chondroids, and guttural pouch mycosis (fungal infection in the guttural pouches).
Other clinical signs can help your veterinarian localize the problem, resulting in less tests and a quicker diagnosis. If nasal discharge is present with a cough, skull radiographs may be warranted because an infected sinus could cause discharge from the nose but also some of the discharge may travel down the throat causing a cough. If the cough only occurs during/after exercise, it is possible your horse has exercise induced pulmonary hemorrhage. In some cases, the blood runs down the throat and causes a cough. If the cough only occurs when your horse eats, conditions such as a cleft palate, dorsal displacement of the soft palate, and soft palate paresis should be ruled out.
Two of the more common causes of cough that owners often confuse are Recurrent Airway Obstruction (RAO), better known as heaves, and Inflammatory Airway Disease (IAD). RAO is a condition that generally affects older horses. These horses show increased respiratory effort at rest, exercise intolerance and a cough. It is frequently caused by an allergy, most often mold or dust. IAD is a condition that generally affects younger horses. Signs also include exercise intolerance and a cough, but IAD horses do not have increased respiratory effort at rest. IAD is also believed to have an allergic component. Treatment for both of these conditions consists of medical therapy and environmental changes. Initially the horse must be treated medically with anti-inflammatory medications and bronchodilators to allow the horse to breathe easier. But the environment of these horses must also be altered so that the inciting factor does not cause a recurrence of the condition. Environmental changes consist of removing the irritants from the horse's environment. This can include giving the horse a stall with a window or by the door to ensure good ventilation and fresh air, turning the horse out to reduce exposure to times when the barn has debris in the air, such as when the stalls are being mucked or when the aisle is being swept, not keeping hay stored above the horse's stall, using shavings that are not dusty, wetting the hay, keeping arena footing well watered to minimize dust, etc. All of these, are ways to manage the horse's environment so the condition will not reoccur.
A horse with a cough is a very vague complaint that many horse owner's have. It is also a frustrating condition for owner's because there are many possible causes so in turn, many tests may need to be performed by your veterinarian. By paying more attention to when and where the cough occurs, what your horse is doing at the time of the cough, and additional clinical signs that your horse may have, your veterinarian will be better equipped to find the cause and help your horse.
Polysaccharide Storage Myopathy (PSSM)
Dr. Cat Ruksznis
Let's face it: no one wants to go to work on Monday morning. In the days where 'horse power' really did refer to the draft horses pulling the cart, their drivers noticed that even the horses were reluctant to move on Mondays. In fact, this condition was dubbed "Monday Morning Disease" - horses were stiff and slow on Monday mornings after a weekend off while still on full feed. We know this disease by many different names today - tying up, rhadbomyolysis, azotemia, etc. Earlier observations to the contrary, this is a true disease of the muscles (mypoathy), not a coffee deficiency! Although horses may develop this disease sporadically, there are also horses with an underlying genetic predispositions. Polysaccharide Storage Myopathy (PSSM) is one such muscle disease.
What causes PSSM?
There are two types of PSSM: type 1, in which the specific genetic mutation has been identified, and type 2, a category which is essentially a catch-all for horses with PSSM that do not have the known mutation. As the name suggests, these horses have abnormal accumulation of a polysaccharide (a sugar) in their muscle cells. Type 1 PSSM is most common in horses descended from Continental European draft breeds (Quarter Horses, Warmbloods, Appaloosas) and has been found in over 20 breeds. These breeds have a mutation in the enzyme responsible for making glycogen (GYS1). Glycogen is a type of sugar which is normally stored in skeletal muscle fibers and used for energy during the first 20 minutes of exercise. In horses with PSSM, there is a greater amount of abnormally constructed glycogen created, which accumulates in the muscle cells. Although the link between abnormal glycogen and muscle cell damage has not been fully elucidated, we do know that the increased activity of the GYS1 enzyme disrupts the normal muscle metabolism during exercise, leading to muscle damage.
Horses with Type II PSSM do not display this mutation in GYSI, but the muscle cells do display abnormal glycogen deposits (mechanism unknown). It is possible that there are numerous, as of yet undetermined underlying causes that we are currently grouping under this heading.
What are the clinical signs?
Diagnosing muscle diseases can be tricky - they are easily confused with colic, acutely, or a lameness problem chronically. Acute clinical signs include sweating, muscle twitching, muscle stiffness, muscle fasciculations, dark colored urine, unwillingness to move and recumbency. Muscles are most often tense over the hind quarters and the signs worsen with continuing exercise. Although episodes are most often triggered by exercise, these signs are not always perfectly correlated.
As the muscle cells are damaged they release a substance known as myoglobin, which is normally contained within the cells. Myoglobin bears a passing resemblance to hemoglobin; the molecule found in red blood cells that allows them to carry oxygen. However, once myoglobin is free in the body it does more harm than good. The molecule accumulates in the kidneys and, in large enough quantities, can lead to renal failure.
Less severely affected horses with low-level chronic disease may show more subtle clinical signs. Poor performance, a bad attitude, lack of energy, slow onset muscle atrophy or unwillingness to track up may all be signs of PSSM.
How can you diagnose PSSM?
To first diagnose a horse with rhabdomyolysis (tying up), a biochemistry panel is very helpful. This test will show elevations in muscle enzymes (AST and CK) which increase with muscle damage. A chemistry panel will also allow your veterinarian to monitor kidney values, if the muscle damage is severe.
In the case that the patient is a breed known to carry the genetic mutation responsible to type I PSSM, genetic testing can be diagnostic. This requires a blood or hair sample to be sent away for testing. Type I or Type II PSSM can also be diagnosed through a muscle biopsy. A small sample of muscle can be examined with specific stains to look for abnormal cellular features and amylase resistant accumulations of glycogen.
What are the treatment options?
When working with a horse you suspect may be tying up, exercise should be stopped immediately. The horse should be offered water, but no other feed. Veterinary treatment of an acute case of rhabdomyolysis includes intravenous fluid therapy to flush the kidneys, muscle relaxants to stop muscle damage and anti-inflammatory/analgesic medication (NSAID's).
That being said, PSSM is primarily managed through exercise and dietary adjustments. After an episode, horses should be gradual brought back into consistent work with no prolonged period of rest. Regular exercise, being ridden or worked 3-4 days a week with access to daily turn out, is very important to horses with PSSM. Initially, exercise should be light (walk-trot) and they should always be warmed up adequately. Regular exercise is thought to improve energy metabolism within the muscle cells.
Horses with PSSM should be fed a diet low in nonstructural carbohydrates (starch/sugar), with a compensatory increase in fat if necessary to meet caloric requirements. There are many commercial options for low starch/high fat diets currently available. Restricting dietary sugars (NSC) from grass or hay is more difficult, but can be achieved though use of a grazing muzzle and/or soaking hay prior to feeding.
Even with excellent management, horses with PSSM will always be predisposed to developing muscle soreness. However, most will show improvement in clinical signs.
Seat Bones from the Rider's Side of the Saddle
By Nancy Wesolek-Sterrett
Dressage Department Head, Meredith Manor International Equestrian Centre
“Sit straight!” I cannot count the number of times I say these words to a student only to get the response, “But I am sitting straight.”
When I first started instructing, it was perfectly clear to me as an observer whether a student sat straight or crooked in the saddle. Crookedness in a horse or a horse unwilling to turn or stay on the rail was often a dead giveaway that the rider was crooked in the saddle. However, what I SAW the rider’s body doing and what the student FELT her body doing in the saddle did not match. There was a disconnect between where the rider’s brain told her ‘straight’ was and the reality I viewed. It took a lot of observation and experimentation to figure out what was going on and how to fix it.
Sitting up straight is a critical skill for riders. At the halt, the rider’s ears, shoulders, hips and heels align when viewed from the side. The small of the back is neither arched nor rounded. Viewed from the front, the horse’s neck, withers and spine form a straight line and the rider’s nose, chin, breastbone, belly button align with the horse’s spine. Viewed from the rear, the rider’s head and spine align with the horse’s spine.
When the rider sits up straight, she puts equal weight in both seat bones. This is fundamental to clear communication with the horse. Understanding how it feels to have equal weight in both seat bones precedes learning to modify those pressures in nuanced ways that communicate information about direction, bend, speed and more to the horse. When the rider has control of her seat bones, she can accurately influence the horse.
Everyone has problems with sitting straight on equally weighted seat bones at one time or another, mainly because we all have a weaker side and a stronger side. Riders tend to draw up their stronger leg therefore putting more weight on the opposite seat bone. Riders who have been ballet dancers or gymnasts may make the easiest transition into the saddle. To walk on a balance beam or move gracefully across the floor, they learned to keep their shoulders balanced over their hips. This is a very important aspect of riding straight in the saddle.
Most riders, however, bring poor postural habits with them when they mount up. They assume the classic ‘computer posture’ with chin jutting forward, shoulders slumping and lower back rounded. This posture removes weight from the seat bones. Some riders slouch off to the left or right placing their hips, shoulders, and head out of alignment. This puts more weight on one or the other seat bone, puts more weight in one or the other stirrup, puts the saddle off center on the horse, or creates any one of several other off balance scenarios.
Take the example of the rider who sits over to the left with more weight on her left seat bone. At the extreme when I view this rider from in front or behind, I may see the saddle pulled off center, the left stirrup hanging lower than the right, and the rider’s ribcage collapsed on the right. Her left shoulder may be higher than her right and her head may be tipped to the right so her ear points at her shoulder. Without putting my hand between her seat and the saddle, I know that she has more weight on her left seat bone than on her right. Or more weight to the left side of the horse then to the right side of the horse.
When someone rides crookedly for years, that crooked position feels normal. Correcting the problem literally requires retraining their brain to understand what straight and balanced, relative to gravity, feels like. It is not easy. Riders with good body awareness (think ballet, yoga, gymnastics, any martial art) can sometimes be talked through any crookedness. I sometimes use my hands to align a rider’s body so that she can feel what it feels like to be straight. But either method can have its drawbacks. If I tell a rider to drop her left shoulder, she may drop her head to the left at the same time. She feels balanced but she is not straight. If I take her knee to push her hips over so they are centered in the saddle, the rider invariably collapses her ribs on that side rather than equalizing the pressure in her seat bones.
Many people sit off to the left in the saddle because they are right handed. Their whole right side is stronger than their left so they draw up the right leg and push themselves to the left. Depending on their personality, some horse will tolerate their rider sitting as much as 2 inches off center before they get annoyed. Most horses begin to show some form of resistance long before that. Riders who sit off to the left usually find their horses do not bend easily to the right, for example.
Riders can play with a number of exercises to help them find ‘straight:’
* Sitting on the horse in front of a mirror or with the help of an observer, note if the horse’s neck, withers and spine are straight and if the rider’s nose, chin, breastbone, belly button, and spine all align with the horse’s center. Correct any rider misalignment and note how the horse’s alignment changes. Use the horse’s alignment to help the rider see and feel what adjustments in her position straighten the horse.
* At the halt, stand up in the stirrups. Are they equal length? Is there equal weight in each one? Is the saddle centered over the horse’s spine? Is the rider’s spine centered over the horse’s spine? Are the riders’ hips level? Are the shoulders level? Does the rider fall forward, backward, collapse the ribcage on one side, arching her back or round her back in order to stay ‘centered’ over the horse? Do this in front of a mirror (or a barn window) if a ground observer is not available for feedback.
* If the rider tends to put more weight in one stirrup than the other, she will push her weight onto the seat bone on the weaker side. Instead of pushing weight into the stirrups, think of pressing the knees to the ground as though kneeling on the ground. This not only helps to equalize the weight in the seat bones but also helps align the heels with the hips.
* Have the rider sit on a swivel chair or large balance ball with her hands underneath her seat bones. The seat bones are the bottom of the bony pelvic bowl. The bony projections we call our ‘hip bones’ are actually the top of this bowl. The actual hip joints are located in the bend between the upper body and thighs where the balls at the top of the thigh bones fit into the sockets of the pelvis. Keeping shoulders, ribcage and hips as level as possible, move weight from one seat bone to the other. Note what a small movement of the hips is required to do this. Shift weight forward and back without arching or rounding the lower back. Keeping the hips as level as possible and the shoulders over the hips, put the seat bones at a slight diagonal and shift weight from one to the other. Play with these movements with the chair facing forward, then swiveling right or left as though turning. These are the subtle movements that a horse feels and responds to.
* Retrain the brain. Right-handed riders should do everyday things with their left hand, vice versa for lefties. Do exercises that make the arms or legs or both cross the body’s midline to help balance the brain’s signals to both sides of the body. Strengthen the weaker side and stretch the stronger side of your body.
* Trust and use the horse’s feedback. Riding on the buckle, make a left turn, a right turn, circles, a serpentine, a half turn on the haunches and observe the horse’s answers to requests from the seat bones. If the responses are not what the rider thought she was asking the horse to do, she can experiment with changes in how she centers herself and weights her seat bones. Her horse will tell her when she gets it right.
*Temporarily ride with the stirrup longer on your stronger side or shorter on your weaker side. If possible, ride without stirrups on a quiet horse. Focus on keeping your shoulders over your hips and your hips centered over your horse’s spine. Note, this may feel uneven or unbalanced to someone who has been riding crooked for a long time.
The only way to give the horse clear, meaningful communication is to start by ‘sitting straight’ then using strong but flexible core muscles to weight and unweight the seat bones for directional guidance and speed control. This is the ‘independent seat’ that a rider must achieve in order to truly influence the horse. Without it, the rider is still influencing the horse. But until she develops a true feel for ‘straight’ in her own body and in the horse’s body, communication with the horse will be unclear, inconsistent, or, worse still, incorrect.