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Roaring (laryngeal hemiplegia)
Dr. Kathy Samley, DVM
What is it?
Laryngeal hemiplegia, commonly called "roaring" is a disease of the upper airway in horses. The larynx is the opening to the trachea, and consists of several pieces of cartilage. The arytenoid cartilages open to allow air into the trachea, and close during swallowing to prevent food and liquid from getting into the trachea. Laryngeal hemiplegia occurs when there is degeneration of the nerve that innervates the muscles of the larynx, preventing the arytenoid cartilage from opening properly. This prevents proper airflow into the trachea and causes a noise heard during exercise. This decrease in airflow can also lead to exercise intolerance. Laryngeal hemiplegia usually only affects one arytenoid, with the left side affected in 95% of cases. The specific cause of the nerve degeneration is unknown but there are likely genetic and acquired components that contribute.
The two main signs of laryngeal hemiplegia are upper respiratory noise during exercise and poor performance. The severity of laryngeal hemiplegia is graded on a scale of 1-4, with 4 being complete paralysis of the arytenoid. The volume and severity of the upper respiratory noise and the amount of exercise intolerance can vary based on the grade of the laryngeal hemiplegia.
Laryngeal hemiplegia is diagnosed through upper airway endoscopy. A small camera is passed up the horse's nares to the level of the larynx. The arytenoid cartilages are examined through several respiratory cycles to assess their movement. The horse cannot be sedated for this procedure, as sedation makes it difficult to properly assess arytenoid function. There are several other conditions that can cause upper respiratory noise in horses, so the larynx and surrounding structures are closely examined for any abnormalities. After a baseline examination, a post-exercise endoscope exam is often performed. The horse is exercised for several minutes and the scope is passed again to assess the function of the arytenoids immediately after vigorous exercise.
Laryngeal hemiplegia is typically a surgical condition and is corrected via a prosthetic laryngoplasty, "tieback," procedure. Two strong sutures are placed through the arytenoid cartilage and attached to one of the other laryngeal cartilages. The sutures help to abduct the arytenoid cartilage, opening up the airway. The laryngeal saccule is removed in order to further stabilize the tieback and decrease upper airway noise. This procedure has a good prognosis for return to athletic function. Additionally, horses with lower grades of laryngeal hemiplegia have shown improvement after several treatments of electroacupuncture.
These images show a before (left) and after (right) a tieback procedure. The left image is from a horse with grade 4 left laryngeal hemiplegia. Note how the left arytenoid cartilage is deviated to the center of the larynx, partially obstructing the trachea. After surgery, the left arytenoid is held open which allows normal airflow.
Effects of Equine-Facilitated Psychotherapy on Post-Traumatic Stress Symptoms in Youth
Research Published in Journal of Child and Family Studies:
Effects of Equine-Facilitated Psychotherapy on Post-Traumatic Stress Symptoms in Youth
Chagrin Falls, Ohio, April 20, 2017– The findings from Tufts University’s equine-facilitated psychotherapy research studying effects on youth with Post-Traumatic Stress Disorder (PTSD) Symptoms was just published in the Journal of Child and Family Studies. The project was funded by Horses and Humans Research Foundation and lead by Principal investigator Megan K. Mueller, Ph.D.
Equine-assisted therapy has become an increasingly popular complementary mental health treatment approach, but there is limited empirical research assessing the effectiveness of this practice. In particular, equine-facilitated psychotherapy has many potential benefits for the treatment of trauma in youth. The purpose of the proposed study was to investigate changes in levels of post-traumatic stress symptomatology and levels of the human-animal bond in children and adolescents ages 10–18 over the course of a 10-week equine-facilitated psychotherapy (EFP) intervention.
Youth in the treatment group participated in 10 weekly two hour EFP sessions, and were compared on changes in post-traumatic stress symptoms with a control group of participants who continued to receive the already existing traditional therapeutic services provided by their treatment facility or outpatient therapist.
Findings suggested a significant decrease in post-traumatic stress symptoms across the intervention for both the treatment and control group, but the treatment group did not decrease significantly more than the control group. These findings suggest that EFP may be an effective additional treatment modality for post-traumatic stress symptoms, but there was no evidence from this initial study that EFP was significantly more effective than traditional office-based therapy. Further research and discussion of the relative benefits of EFP compared to traditional treatment modalities is warranted.
Paul Haefner PhD, of the Horses and Humans Research Foundation board of directors, stated “This research project was exceptionally significant because it put Equine Facilitated Psychotherapy on the map. It shows that this professionally facilitated treatment is a viable option. It gives us an important recognized tool when working with troubled youth who urgently need a treatment option that will help them progress during vulnerable time in their lives.”
Mission: Through sustained investment in rigorous research, HHRF serves as a catalyst to advance global knowledge of horse-human interactions and their impact on health and wellness.
Horses and Humans Research Foundation (HHRF) is dedicated to funding research to investigate the equine-assisted activities and therapies field. Since its founding, HHRF has awarded over $500,000 in professional research efforts led by eleven research teams in the United States, Canada and Germany. HHRF is a non-endowed foundation dependent solely on donations. To make a donation and/or learn more about this and other Horses and Humans Research Foundation projects visit http://www.horsesandhumans.org
Equine Acupuncture - A Scientific Approach
Written by intern Dr. Laura Wodzinski
New England Medical & Surgical Center
Acupuncture has been a part of Traditional Chinese Medicine for over 5,000 years and has grown in popularity in western medicine in the last few decades.2 With more evidence-based research emerging in human and veterinary medicine proving its effectiveness, it is becoming more recognized as a valid treatment modality in medicine. The World Health Organization has concluded that acupuncture is a valuable therapy in treating several human diseases. But how does this seemingly “voodoo” therapy of needling work?
The exact mechanism of acupuncture has yet to be discovered in the last 5,000 years, however numerous responses to needling have been documented in thousands of evidence-based studies. One of the most common uses of acupuncture treatments is for chronic pain. To explain a mechanism of how acupuncture can provide analgesia in chronic pain, consider this: You are chopping up apples to feed you horse the perfect bite-sized portions, when you accidently slice you finger with the knife. Your first reaction will be an involuntary reflex originating from a fast nociceptive fiber signal to your brain telling you to pull your hand away. The second reaction is to grip your cut finger an apply pressure. The pressure provides pain relief by activating mechanoreceptors found under the skin and the original sharp pain ceases. The brain is only able to handle one source of pain at a time, as described by the Gate Control Theory of Chronic Pain. With the pressure applied, the body is able to down regulate the sharp pain from the cut and allow your body’s “internal pharmacy” to be activated.3,6 In chronic pain, the fibers are thick and slower transmitting fibers that cause a more dull and throbbing pain. In contrast, sharp pain is associated with fast conductive fibers that transmit messages to the brain very quickly to create a response that will protect the body. When acupuncture needles are inserted into the skin and tissues, they cause micro-inflammation at the site and stimulate the fast fibers to carry signals to the brain, overriding the slow, chronic pain fiber messages.3 With this new, fast signal from the acupuncture, the brain is able to activate its neurochemical pharmacy to produce substances such as endorphins, serotonin, and opioids that make the animal feel good and down regulate pain. This process is known as neuromodulation.
The Central Nervous System (CNS) has a major role in the effects of acupuncture. By placing needles in acupuncture points, or areas that are richly supplied with nerve endings, it causes stimulation that creates a signal that is transmitted to the spinal cord, and then the brain. Once at the brain, key centers including those responsible for digestion, cardiopulmonary function, and the endocrine system are affected and a response can be created. Recent studies have used functional magnetic resonance imaging (fMRI) to evaluate the effect of specific acupuncture points and their direct effect on areas of the brain.2 In addition to direct nerve stimulation, the needle engages with collagen fibers, connective tissue matrix, and vessels under the skin that with manipulation of the needle causes activation of mechanoreceptors (a receptor that respond to pressure and transmit messages to the CNS), nociceptors (sensory receptors), vasodilation, and tissue biochemistry changes.1
Another use for acupuncture is relieving trigger points. A myofascial trigger point is described as: “a hyperirritable spot in skeletal muscle that is associated with a hypersensitive palpable nodule in a taut band.”1 Most humans can find these in their neck and shoulders after being hunched over a computer all day. In the equine patient, these trigger points can be associated with lameness, weakness, sore backs, and decreased flexibility. Excessively strenuous activities, repetitive strains, or even stall rest can precipitate the development of triggers points in addition to disturbances such as poor shoeing and an improperly fitted saddle. 1 Acupuncture works right at the site of the maximum soreness by inserting the needle directly into the center of the trigger point, and twisting it back and forth until the muscle fibers release. Localization of trigger points is done in our animal patients by palpating tight bands and watching the animals’ response in the form of a twitch or avoiding the pressure. Trigger points can form in any muscle at either the muscle belly or the myotendinous junction. They are not necessarily correlated with acupuncture points.
How can acupuncture be used to treat my horse?
In the equine patient, acupuncture can be used for a variety of musculoskeletal issues such as back pain, neck stiffness, laminitis, poor saddle fit and much more. Acupuncture treatments typically start with a “scan” of points that consists of running an acupuncture pen (or needle cap or Sharpie in a lot of cases!) over the horse to determine areas of sensitivity. Over sensitive areas, the horse will often flinch or move away from you, indicating there is some level of soreness at that site. This soreness can be due to a primary problem, or can be secondary muscle soreness from compensating for lameness somewhere else in the body. Regular acupuncture treatments can reduce muscle soreness during increased work or even improve comfort during their routine show schedule. Back soreness is a common condition that acupuncture can improve whether it is from an ill-fitting saddle or kissing spine lesions. Regular acupuncture treatments may even extend the interval between kissing spine treatments or mesotherapy.
Another common use for acupuncture in the equine patient is colic. Ileus, or decreased or absent gastrointestinal motility, is a common complication following colic surgery that can significantly compromise the recovery of the horse. The motility of the gastrointestinal tract is influenced by the sympathetic nervous system, the “flight or fight” response, and the parasympathetic nervous system, the “rest and digest” portion of the nervous system.4 Acupuncture aims to manipulate these systems through neurotransmitters acting on the autonomic nervous system to promote intestinal motility. Acupuncture should be considered and adjunctive treatment to colic with Western medicine therapies and diagnostics being performed first.
Reproductive disorders in both mares and stallions can be treated with acupuncture through neuro-hormonal regulation, pain relief, and smooth muscle contractions. In the stallions, issues including loss of libido, infertility, and poor semen quality can be improved using acupuncture. 5 In mares, cycle issues including failure to ovulate, sporadic heat cycles, or anestrus can be better regulated through acupuncture via mediation of the nerves that regulate and control the reproductive tract and the pituitary gland which influences hormone secretion. 5 Additionally, acupuncture’s effect on smooth muscle contractions can aid in the eliminate of fluid in the uterus and urine pooling that could compromise conception.5
Although seemingly abstract, acupuncture is a science-proven treatment modality that can help in a variety of diseases, most notably chronic pain. I recommend acupuncture treatment to my clients with the caveat that, like some pharmaceutical medications we take, acupuncture may not work for all animals or people or may take several treatments to see an effect. This treatment modality has very few negative side effects, is minimally invasive, and may have a profound positive response in your equine athlete- what are you waiting for?
1. Robinson, Narda G. "One Medicine, One Acupuncture." Animals 2.4 (2012): 395-414. Web.
2. Dorsher, Peter T. "Neuroembryology of the Acupuncture Principal Meridians." Medical Acupuncture (2017)
3. Sypniewski, Lara. "Dog Acupuncture." TEDxOStateU. 07 Feb. 2017. YouTube. Web. 07 Feb. 2017.
4. Story, Melinda. "Equine Gastrointestinal System." Medical Acupuncture for Veterinarians. Colorado, Fort Collins. 07 Feb. 2017. Lecture.
5. Holt, Timothy. "Veterinary Medical Acupuncture and Reproduction." Medical Acupuncture for Veterinarians. Colorado, Fort Collins. 07 Feb. 2017. Lecture.
6. ABPP, William W. Deardorff PhD. "Modern Ideas: The Gate Control Theory of Chronic Pain." Spine-health. N.p., n.d. Web. 08 Feb. 2017.
Lauren Hughes, DVM
Anaplasmosis is an infectious disease affecting horses most commonly during tick season. A majority of cases are reported in California but it has also been identified all over the United States and worldwide including right here in New England. Knowledge of this disease and early recognition can greatly improve the prognosis for your horse.
This disease can affect horses of all ages and the clinical presentation can vary greatly depending on the duration of illness. Horses with Anaplasmosis can display a large variety of clinical signs ranging from a high fever (103-105 F), depression, decreased appetite, mild limb swelling, reluctance to move, icterus, and in rare cases incoordination/ataxia. The fevers are normally highest in the first few days of infection but can persist up to 12 days. Icterus, a build up of bilirubin, leads to a yellowing most commonly appreciated on the sclera of the eyes and oral mucous membranes. It is important that your veterinarian perform bloodwork while working up a horse with icterus as any disease process affecting the liver can also lead to icterus and should be ruled out in a case of Anaplasmosis.
Anaplasmosis is a tick borne disease caused by the bacterium Anaplasma phagocytophilum. This bacteria is carried by the deer tick, the same tick that carries and spreads Lyme disease. A horse becomes infected with the bacteria through the bite of a tick and it enters the blood stream where it lives within white blood cells. The organism acts to cause destruction of red blood cells, white blood cells and platelets and low levels of these cells are often seen on bloodwork when working up a horse with Anaplasmosis.
There are multiple ways to diagnose this disease with the most definitive being identification of the organism within the white blood cells on a blood smear. Even in cases of active infection, the bacteria may only infect a small number of cells so it is not always visualized. Titers can also be performed to assess immune response and confirm exposure to the bacteria. Lastly polymerase chain reaction (PCR) tests can be performed to recognize the DNA of the bacterium. Routine blood work may also be consistent with the disease process and show decreased red blood cell, white blood cell and platelet levels. In many cases it is difficult to obtain an immediate diagnosis so treatment if often initiated prior to confirming infection.
Early recognition of the disease and treatment with appropriate antibiotics often leads to a good prognosis and full recovery. Administration of a tetracycline antibiotic can be done intravenously or orally and can include oxytetracycline, doxycycline or minocycline depending on the individual case. In most cases fever and other clinical signs will dramatically improve within 48 hours of initiating antibiotics. Some horses with a mild form of the disease may recover without treatment but can also relapse within a few weeks so treatment is highly recommended. Banamine or other anti-pyretics are often used to help control the fever.
More severe cases with neurologic signs often require supportive care and may benefit from corticosteroid treatment.
Prognosis is excellent if the disease is recognized early and treatment is initiated. In more severe cases where neurologic signs develop additional treatment may be needed and permanent injury may occur due to incoordination/ataxia. Fatality is rarely reported due to this disease unless secondary complications occur.
There is currently no vaccine for this disease. Immunity is acquired after infection and normally lasts around two years following an active infection. The most important aspect of disease prevention is tick control by routinely checking your horses for ticks and removing them. Topical products are also available that can help against ticks.
If you have any questions or concerns regarding Equine Anaplamosis do not hesitate to contact the doctors of New England Equine Medical & Surgical Center.
Fig 1. Icteric Sclera: https://s-media-cache-ak0.pinimg.com/originals/3b/f8/bf/3bf8bfdcfba519c86e25c93dba303247.jpg
Fig 1. Icteric MM: https://www.vetstream.com/images-equis/thumbs/21_165672-thumb.jpg
Fig 2. Bloodsmear: https://anokaequineblog.files.wordpress.com/2014/03/morula.jpg
Merck Vet Manual. Webpage. <http://www.merckvetmanual.com/mvm/generalized_conditions/ equine_granulocytic_ehrlichiosis/overview_of_equine_granulocytic_ehrlichiosis.html>.
Reed, Bayly and Sellon. Equine Internal Medicine- 3rd Edition. St Louis: Elsevier, 2010. Print
Basics of Lameness
The 411 on the Basic Lameness Exams - Written by Dr. Laura Wodzinski
Equine lameness is an important and prevalent area of equine medicine. Whether solving a hoof abscess or diagnosing a meniscal tear in a stifle, the basic fundamental principles of a lameness work up apply. This article will cover the basic first steps of a lameness evaluation in addition to a few of the most common nerve blocks your veterinarian may perform.
When assessing a horse with a lameness, it is important to proceed with an approach that is methodical as well as cost effect. For this reason, many veterinarians begin with basic palpation and baseline lameness examination. On palpation, your veterinarian is looking for areas of heat, swelling, joint or tendon sheath effusion, increased digital pulses, or any areas that are sensitive or reactive to palpation. Depending on the degree of lameness, horses are trotted in straight lines and circles on hard ground and soft footing for the baseline lameness assessment. The variation in lameness depending on the surface can help determine soft tissue origin or bone, as soft tissue pathologies are often accentuated in the soft footing. The degree of lameness is evaluated on a scale set by the American Association of Equine Practioners (AAEP). This is a scale of 0-5 with 5 being the most severe lameness.
After achieving this baseline lameness, flexion tests can be performed based on the baseline lameness findings. A flexion test is when specific joints or regions of a limb (lower versus upper) are flexed for several seconds and then the horse is trotted off immediately. An increase in lameness after flexion helps to narrow down the region of interest to be the source of the pain. Additionally, hoof testers may be used to check for sensitivity in the foot. By squeezing the hoof capsule in several areas and evaluating the horses’ response perform this test, the areas of sensitivity can be determined if the horse tugs his leg away from the stimulus. Depending on the location of sensitivity, further diagnostics can be used to focus on these areas.
After identifying the affected limb(s) with a lameness evaluation, your veterinarian may decide to proceed with regional nerve blocks. These blocks are typically performed starting distally, or lowest on the limb, and working up the limb as the blocks desensitized everything below where the needle is inserted. There are various local anesthetic drugs that can be used for nerve blocks, however the most popular is Carbocaine (mepivacaine). This medication takes approximately 10-15 minutes to begin working and has a duration of action of approximately 2 hours. After allowing the block to begin taking effect, the horse is trotted again to evaluate the effect of the nerve block. An improvement in the lameness indicates the block desensitized the source of pain. Below is a list of common nerve blocks starting from the block lowest on the limb.
Palmar Digital Nerve block (PDN): This block is performed just above the heel bulbs on the inside and outside palmar/plantar digital nerves. The following structures are desensitized:
· >Caudal third to two-thirds of the sole, including the heel bulbs>
· >Navicular bone and bursa>
· >Palmar coffin and pastern joints>
· >Distal sesamoidean ligaments, deep digital flexor tendon and sheath>
· >Frog corium and digital cushion>
· >Wings of the coffin bone>
Abaxial Nerve block: Performed just below the fetlock joint on the inside and outside of the limb, this nerve blocks desensitizes the dorsal and palmar branches of the palmar nerve. In addition all of the areas affected by the PDN block, the abaxial block desensitizes the following major locations:
· >The long pastern, short pastern, and coffin bones>
· >Entire corium and sole>
· >Dorsal branches of the suspensory ligament>
· >Digital extensor ligament>
· >Possible diffusion into the fetlock joints and proximal sesamoid bones>
Low 4 Point: This block requires instillation of block in four different locations above the fetlock joint. The palmar and palmar-metacarpal nerves are blocked by inserting needles between the deep digital flexor tendon (DDFT) and suspensory ligament (SL) and just below the button of the splint on the inside and outside of the limb. In addition to all of the structures previously mentioned in the PDN and abaxial blocks, the Low 4 point block desensitizes the following structures:
· >Coffin, pastern, and fetlock joints>
· >Deep digital flexor sheath>
· >Soft tissue structures of the pastern and foot>
Joint Blocks: Certain joints may be blocked in order to get a very specific block when the area of pathology is suspected to be articular. Joint blocks require aseptic preparation as the needle and Carbocaine will be injected directly into the joint.
The information that can be obtained from a basic lameness examination, flexions, and nerve blocks can give the information needed to decide on further diagnostics. Radiographs and ultrasound are the most common diagnostic modalities used in equine lameness, however advanced imaging such as magnetic resonance imaging (MRI), computerized tomography (CT), and nuclear scintigraphy (Bone scan) are also very informative. MRI and CT will need to be performed under general anesthesia due to the necessity of the horse being absolutely still.
Lameness work-ups are an essential part of the equine health care. This common systematic approach can help localized the affected area to focus diagnostic efforts and make the correct diagnosis and treatment plan.
1. "LAMENESS EXAMS: Evaluating the Lame Horse." American Association of Equine Practitioners. N.p., n.d. Web. 09 Nov. 2016.
2. Service, Field. "Diagnostic Anesthesia." Diagnostic Anesthesia. N.p., n.d. Web. 09 Nov. 2016.
3. Vandenberghe, Aurelie. "Tenogenically Induced Allogeneic Mesenchymal Stem Cells for the Treatment of Proximal Suspensory Ligament Desmitis in a Horse." Frontiers. Front. Vet. Sci., 22 Oct. 2015. Web. 09 Nov. 2016.
Equine Gastric Ulcer Syndrome
Dr. Kathy Samley
>>>>>Equine gastric ulcer syndrome is a common condition in horses and foals. While any horse can develop gastric ulcers, they tend to be more common in horses in high levels of work. Studies have shown that the prevalence of gastric ulcers can be as high as 60-90% in show horses and thoroughbred racehorses. The equine stomach consists of two sections, the squamous (non-glandular) portion and the glandular portion. The two sections are separated by a line called the margo plicatus. Ulcers in the squamous portion of the stomach develop from the excess production of gastric acid, which damages the squamous mucosa leading to the development of an ulcer. The glandular portion of the stomach has a protective coating that contains bicarbonate and other substances to buffer the gastric acid, making it less prone to ulceration than the squamous portion. Ulcers in the glandular part of the stomach are less well defined and research is still being done to investigate their causes and pathophysiology. Risk factors for development of gastric ulcers include feeding a high starch diet, feeding a large amount of grain at a time, strenuous exercise, and stressful events such as traveling or illness. Gastric ulcers can present with a wide variety of different signs depending on the horse. Common signs include changes in behavior, decreased performance or reluctance under saddle, poor appetite, mild weight loss, and mild episodes of colic.>
How are gastric ulcers diagnosed?
The only way to definitively diagnose gastric ulcers is with a gastroscopy procedure. This procedure can be done either on the farm or in the hospital. The horse must be fasted overnight so that their stomach is empty for the procedure. For the exam, the horse is sedated and a small camera is passed up the horse’s nose, down the esophagus, and into the stomach. The stomach is then inflated with air so that the entire stomach can be visualized. The parts of the stomach that are examined include the cardia (entrance to the stomach), the greater and lesser curvature, and the pylorus (where the stomach exits into the small intestine). Before the gastroscope is removed, the extra air is removed from the stomach to prevent colic due to gastric distension.
Gastric ulcers are graded on a scale of 1-4 based on their severity. Grade 1 ulcers are the most mild and consist of areas of reddening or hyperkeratosis of the mucosa. Grade 4 ulcers are the most severe and consist of extensive or actively bleeding ulcers.
How are gastric ulcers treated?
The main treatment for gastric ulcers is omeprazole, commonly known as Gastrogard or Ulcergard. Omeprazole is a proton pump inhibitor which blocks the enzyme that releases gastric acid into the stomach and therefore helps to decrease the acidic environment of the stomach. For most ulcer types, typical treatment includes administering a full tube of omeprazole once a day for 28 days. Before the end of the omeprazole treatment, a recheck gastroscopy is recommended to ensure complete healing of the ulcers. For severe ulcers, sucralfate may be used as part of the treatment regimen. Sucralfate binds to the ulcer and forms a protective barrier from the acidic stomach environment.
How can I help prevent my horse from developing gastric ulcers?
If your horse is prone to gastric ulcers, there are several steps that can be taken to help prevent recurrence of ulcers in the future. A preventative dose of omeprazole (250 lb dose or ¼ tube for a 1000 lb horse) can be given before stressful events such as traveling, competitions, or switching barns. Since omeprazole takes three days to reach its full effect, this should be started at least three days prior to the event and continued for the duration of the event. Feeding a higher fiber, low starch diet will lower the gastric pH, and help to prevent ulcers. Hay or pasture should be made available as frequently as possible. Feeding hay in a nibble net is a good way to provide continual access to small amounts of hay throughout the day. If possible, hay should be fed before grain meals to provide a buffering effect. Additionally, there are many supplements available that contain antacids. These supplements can be fed with every grain meal to help buffer the acidic environment of the stomach.