Equine Vet www.modernequinevet.com
Vol 9 Issue 4 2019
Diagnosing Respiratory Disease in Equine Athletes Technician Update: Dynamics of Dynamic Respiratory Endoscopy Endocrine-Disrupting Chemicals May Be Linked to Metabolic Syndrome Restrictions on Race-Day Furosemide Use
TABLE OF CONTENTS
4 Diagnosing Respiratory
Dysfunction in the Equine Athlete Cover photo: Shutterstock/Maksym Gorpenyuk
Endocrine-Disrupting Chemicals Linked to Equine Metabolic Syndrome......................................................10 TECHNICIAN UPDATE
The Dynamics of Dynamic Respiratory Endoscopy..................13 NEWS
Putting Veterinarians in Rural Communities............................11 Thoroughbred Racing Announces New Restrictions on Race-Day Furosemide Use.................................12 ADVERTISERS Standlee Premium Western Forage.........................3 American Regent Animal Health.............................5 Merck Animal Health..................................................7
Avalon Medical.............................................................8 AAEVT............................................................................17
Equine Vet SALES: Matthew Todd • Lillie Collett EDITOR: Marie Rosenthal ART DIRECTOR: Jennifer Barlow CONTRIBUTING WRITERS: Paul Basillo • Adam Marcus COPY EDITOR: Patty Wall Published by PO Box 935 • Morrisville, PA 19067 Marie Rosenthal and Jennifer Barlow, Publishers PERCYBO media publishing
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Diagnosing Respiratory Dysfunction
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Respiratory dysfunction is
one of the primary factors that limits work output, according to Mike Major, DVM, MS, DACVS, of Oakridge Equine Hospital, in Edmond, Okla. “A horse is incredible,” he said. “Their respiratory system is pretty much a finished product. There isn’t much improvement that comes about with training.” The horse’s heart and lungs are large compared with other species, which enable it to perform the work that humans ask of it. For a horse to carry a rider 20 miles per hour, it has to increase its oxygen consumption 40-fold over rest. It’s respira-
B y 4
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M a r i e
tory rate increases 10 times and its tidal volume increases 5 times over rest. The airflow through the upper respiratory tract (URT) increases from 4 L/sec to nearly 100 L/sec. By comparison, human athletes’ peak oxygen uptake is about 6 times their resting rate. In addition to moving air, the URT warms and humidifies the air, filters it, shares a passageway with the digestive tract and gives the horse a voice. The upper and lower respiratory tract are complex systems. The nasopharynx and larynx is a series of musculomembranous walls and valves, with many moving parts
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1 Data on file. 2 Adequan® i.m. Package Insert, Rev 1/19. 3 Burba DJ, Collier MA, DeBault LE, Hanson-Painton O, Thompson HC, Holder CL: In vivo kinetic study on uptake and distribution of intramuscular tritium-labeled polysulfated glycosaminoglycan in equine body fluid compartments and articular cartilage in an osteochondral defect model. J Equine Vet Sci 1993; 13: 696-703. 4 Kim DY, Taylor HW, Moore RM, Paulsen DB, Cho DY. Articular chondrocyte apoptosis in equine osteoarthritis. The Veterinary Journal 2003; 166: 52-57. 5 McIlwraith CW, Frisbie DD, Kawcak CE, van Weeren PR. Joint Disease in the Horse.St. Louis, MO: Elsevier, 2016; 33-48. Adequan and the Horse Head design are registered trademarks of American Regent, Inc. © 2019, American Regent, Inc. PP-AI-US-0222 2/2019
Photos courtesy of Dr. Mike Major
A dynamic endoscopic exam being performed while the horse competes at a barrel race
controlled by coordinated muscle contractions. The small airway diameter is dynamic—constricting during rest and dilating during exercise. The alveoli and capillaries that enable gas diffusion must withstand high-pressure swings.
Resting Vs. Dynamic Endoscopy ENDOSCOPY AT REST CAN RELIABLY DIAGNOSE • Recurrent laryngeal neuropathy • Persistent DDSP • Persistent aryepiglottic entrapment • Epiglottis abscess, epiglottis deformity • Subepiglottic cyst • Arytenoid chondritis • Pharmgeal laryngeal cicatrix • Guttural pouch disease • Pharyngitis DYNAMIC ENDOSCOPY CAN RELIABLY DIAGNOSE • Intermittent dorsal displacement of soft palate (iDDSP) • Vocal cord collapse • Corniculate process collapse • Aryepiglottic fold collapse • Pharyngeal collapse • Epiglottis retroversion 6
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“Everything has to open up, dilate and fix when the horse goes fast at racing speeds or high exercise,” Dr. Major explained. “The bottom line is that everything has to work properly for maximal efficiency from the nares all the way to the lungs. A very small decrease in diameter of the airway can cause a really big change in resistance to airflow. Minor respiratory dysfunction can really diminish the work output.” Even events that last a few seconds can see a decrease from a respiratory dysfunction, he explained. And that diminished work output is what brings the athlete to the veterinarian, frequently with vague complaints of hearing a noise or the horse just isn’t doing right. “The hardest thing we have to deal with as veterinarians is the horse that comes to us and [the owners] are just saying, ‘Doc, he’s just not doing right,’” explained David Frisbie, DVM, PhD, DACVS, DACVSMR, a professor of equine surgery at the Orthopedic Research Center at Colorado State University and partner in Equine Sports Medicine LLC. The first step is the same as for any other problem, according to Dr. Major. Take a good history and do a thorough physical examination. “You don’t just want to go and stick a scope up their nose right away. You need to get the background. That will be pivotal to getting the right diagnosis and determine treatment,” Dr. Major said. As the horse is worked up, remember there could be multiple issues that need to be addressed, he warned. Determine whether or not it is a respiratory issue. A horse that is not performing well or is breathing heavily could have a cardiac issue, for example. Tachypnea may be due to fatigue, discomfort, or apprehension. Lameness, myopathy, anhydrosis, cardiac insufficiency from
a murmur or arrhythmia could all cause breathing issues and poor performance. Conversely, consider respiratory conditions when a horse is presented for lameness, he said. Behavior issues can be from anticipation of hypoxia, not musculoskeletal pain. Pleuropneumonia can present as front-end lameness. “Pleuropneumonia can make a horse look stiff and wide in the front end. Every horse that is acting up isn’t sore. It may be that it can’t breathe well,” he warned. “There are lots of other things that could cause a horse to breathe rapidly or labored, including lack of fitness, discomfort, apprehension, or cardiac issues. Down in my part of the woods, we will see anhydrosis cases. They are presented because they are not working and they are huffing and puffing and lack stamina,” he said. So, do a differential to see what the history and physical examination is telling you. After assessing the general body condition and health of the horse, do an examination that eliminates nonrespiratory problems: temperature, respiration and heart rate, thoracic auscultation, cursory musculoskeletal, lameness and neurological exams looking for nerve damage, ataxia, weakness and atrophy. “When I take a history, I like to get information from the person who knows the horse the best and that is sometimes the rider or the trainer. Try to determine where that horse is at in terms of its training and its fitness,” he said. A frequent complaint is an abnormal respiratory noise, which is strongly suggestive of an upper airway disorder, according to Dr. Major. “Most of your upper respiratory cases are going to be accompanied by an abnormal respiratory noise,” he said. “You can’t rule out upper respiratory problems [without a noise], but you certainly can have
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a high suspicion if they are making noise. “Sometimes, there is not a noise, or they just don’t recognize it because of all the other noise during competition, but there are some cases with upper respiratory problems—notably soft palate displacement—where they actually don’t make any noise.” Lower airway issues generally don’t make a noise when they breathe, but they are more likely to have a cough associated with a lower airway issue than an upper respiratory case. Occasionally, a URT case will cough because of irritation in the throat. The URT examination will look at the air movement through both nostrils, and look for swelling and asymmetry of the sinus region. Check for surgical scars ventral and lateral to the larynx.
Palpating the larynx should also be part of the examination, but Dr. Major said that it takes practice to learn to do it correctly. The palpation should agree with the endoscopy results. “I think laryngeal palpation is definitely a lost art and definitely a learned art, but mainly what we are checking for is atrophy,” he said. Palpate both sides of the larynx and compare the muscular process. Check the back of the cricoid cartilage to see if there is atrophy and see if those cartilages feel more prominent." The resting upper airway endoscopy is the first diagnostic modality used to find URT obstruction, and it is readily performed by most equine practitioners, he explained. It can determine many structural abnormalities and some functional deficits.
“When I get through my history and physical exam, I am probably going to stick an endoscope up his nose and look at the respiratory tract. More than likely that is going to be my starting step. Maybe it’s all I need to do,” he said. “But depending on what I find, I might also want to do some ultrasound of the chest or skull films, or we may have to schedule a dynamic endoscope examination.” Sedation can affect the function of the larynx, so some other method will be needed to restrain the horse during the procedure. Dr. Major prefers to put the horse in a standing stock if possible and to use a twitch. It’s important for the staff, the horse and the equipment to be safe. Look in both nasal passages, ethmoid and nasomaxillary regions, nasopharynx, including the soft palate, guttural pouches, larynx and
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Grade 4 recurrent laryngeal neuropathy
Photos courtesy of Dr. Mike Major
Dorsal displacement and ulceration of the soft palate
trachea, he suggested. The best time to check the nasal passages is as the scope is withdrawn, he said. Always check the guttural pouches because they can be a source of bacterial or fungal infections that can affect nerve and soft-palate function. They may not have swelling or an exudate. “A resting upper endoscopy is commonly done everywhere. We can get a lot of information and diagnose a lot of problems just by that one procedure, but we are limited in conditions involving dynamic airway collapse that happen at exertion,” he said. Some veterinarians will try to increase the value of the resting upper airway endoscopy by stimulating a swallow response or scoping the animal right after some exertion, but the findings are limited. “I try to make my client aware of the limitations. Yeah, it’s a great tool but there are a lot of things we don’t know when we are finished with this procedure.” Sometimes laryngeal ultrasonography can be useful because it is sensitive and specific and provides an extraluminal view of cartilages and intrinsic muscles. Combined with endoscopy and laryngeal palpation, it can help distinguish be-
tween laryngeal conditions, such as recurrent laryngeal neuropathy (RLN), arytenoid chondritis dysplasia, or mild chondritis cases. A horse with RLN probably doesn’t need a dynamic endoscopy, but many other problems will. The dynamic endoscopy is becoming the gold standard for upper airway diagnosis. “The dynamic endoscopy has revolutionized what we understand with upper airway conditions and has led to an explosion of knowledge about URT dysfunction,” he said, because it gives the veterinarian a truer picture of what is happening during exertion. However, it does not completely duplicate actual competition. Up to 48% of horses have multiple abnormalities found on the dynamic exam that would not have been found with a resting endoscopy, according to Dr. Major. The over-the-ground dynamic endoscopy is the more common choice over a treadmill dynamic examination for many reasons. It takes fewer staff members to perform the test, the scoping is done while the horse is ridden—so the rider can control the head position, and it more closely resembles
what is happening when the horse is worked. However remember that having a scope in its nose during work is not normal, so it is not an exact replication of exercise. The over-ground scope is probably less dangerous to the patient, too, because it doesn’t have to be trained to use a treadmill. That doesn’t mean there aren’t negatives to the test, he said. You have to have a big enough facility to ride the horse, it has to be scheduled, and it is recorded and reviewed later, so if the scope moves or gets plugged with mucus, the entire study is invalidated. “Keep in mind, one of the disadvantages is that the rider controls the intensity of the work, so it can be a little harder to get the horse tired and to push the horse to the point that it needs to be pushed to get your findings,” he said. “Owners come in for a quick diagnosis and a fix, and I tell them, ‘it’s worth a dynamic endoscopy and we are going to have to schedule that’.” It can be a hassle and an additional cost, but it is usually worth it. Dr. Major spoke at the 64th Annual Convention of the American Association of Equine PracMeV titioners.
OUR TECHNICIAN UPDATE PRESENTS CASES USING DYNAMIC ENDOSCOPY ON PAGE 15. ModernEquineVet.com | Issue 4/2019
LINKED TO EQUINE METABOLIC SYNDROME
icals (EDCs) in a horse's environment may play a role in the development of equine metabolic syndrome (EMS). This finding could explain some of the variability in EMS severity that can't be explained by other commonly measured factors, such as diet, exercise and season, according to researchers at the University of Minnesota.
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â€œThis is a pivotal piece of a very complicated jigsaw puzzle. There are a lot of horse owners out there who are very diligent about providing their horses fantastic care, but the horse is still diagnosed,â€? said Molly McCue, DVM, MS, PhD, professor and interim associate dean of Research in the College of Veterinary Medicine, University of Minnesota. "It's important to be aware that these chemicals
contribute to the problem, so we can look for ways to reduce horses' exposure to them." The team studied more than 300 horses from 32 farms in the United States and Canada. They focused on Welsh ponies and Morgan horses, because these breeds are more likely to develop EMS than others. The team collected data on the horses' lifestyles, including diet, exercise and
past illnesses, as well as their farm location. Researchers also examined plasma from the horses and looked for EDCs that affect receptors in the horse (estrogen [EEQ] and aryl hydrocarbon [TEQ] receptors). Simultaneously, they determined whether an individual horse had blood-test results consistent with an EMS profile (including insulin and glucose-at-rest and following a sugar challenge). The team analyzed the results to look for correlations between plasma EDC concentration and these variables.
Horses are likely to come into contact with EDCs through their food. EMS, which has no cure, is characterized by endocrine abnormalities in horses and ponies. Affected horses and ponies have a tendency to develop pockets of fat and/or become obese, and they have altered insulin dynamics. EMS also is one of the most common causes of laminitis. “The more we know about a disease, especially a devastating and incurable disease like EMS, the more we can find innovative ways to prevent it,” said Kelly Diehl, DVM, DACVIM, (SAIM), the Morris Ani-
Endocrine-disrupting chemicals are humanmade substances used in products, such as pesticides and plastics. EDCs' Role Unclear
The accumulation of EDCs may explain some environmental variance seen in horses with EMS, but the precise role and dose response to EDCs in horses with EMS is not clear at this time, they said. Endocrine-disrupting chemicals usually are human-made substances found in products such as pesticides, plastics and personal care products. They are heavily prevalent in the environment and can mimic a body's hormones, blocking real ones from doing their jobs. Because of this, they are known to produce harmful effects in humans and wildlife.
mal Foundation interim vice president of Scientific Programs. “While EDCs are difficult to avoid at the moment, the information from this study will greatly improve veterinarians' ability to predict the disease and provide opportunities to prevent it.” This is the first study to examine associations between EDCs and disease in domestic animals. Dr. McCue said it remains to be seen how significant the association is, but hopes future studies will further scientific understanding and help advance veterinary care for horses. MeV The study was funded by the Morris Animal Foundation
For more information: Durward-Akhurst SA, Schultz NE, Norton EM, et al. Associations between endocrine disrupting chemicals and equine metabolic syndrome phenotypes. Chemosphere. 2019; 218: 652 DOI: 10.1016/j.chemosphere.2018.11.136 https://www.sciencedirect.com/science/article/pii/S0045653518322434
Putting Veterinarians in Rural Communities Senators Mike Crapo (R-Idaho) and Debbie Stabenow (D-Mich.) reintroduced the Veterinary Medicine Loan Repayment Program Enhancement Act (S. 1163). If passed, this bill will play a critical role in addressing regional shortages of food animal and public health veterinarians in rural and agricultural communities in the United States. "Veterinary shortages are one of the many significant challenges facing farmers and ranchers today," said John de Jong, DVM, president of the American Veterinary Medical Association (AVMA). "If we don't take steps to address these shortages, we're likely going to see an increase in animal disease incidents that impact our economy and even public health. We're tremendously grateful to Senators Crapo and Stabenow for their continued leadership on this issue, and the work of all lawmakers who are supportive of this legislation." In 2019, the Department of Agriculture's National Institute of Food and Agriculture (USDA NIFA) designated 190 regions in 44 states as suffering from shortages of food animal or public health veterinarians, the most in the program's history. Unfortunately, student debt is a key driver of these shortages, according to the AVMA. In 2018, average student debt for veterinarians who graduated with loans topped $180,000. At the same time, food animal veterinary careers typically pay less than companion animal veterinary careers. This income disparity can make it financially challenging for new veterinarians to pursue opportunities in food animal medicine. The Veterinary Medicine Loan Repayment Program helps address this income disparity and incentivize veterinarians to serve in high-need areas by providing educational loan assistance to veterinarians who commit to food animal or public health practice in USDA-designated veterinary shortage areas for at least three years. While the program has been tremendously successful in closing access gaps since its inception in 2010, shortage areas persist and the program consistently receives more applications than funding allows. The bill would end a withholding tax applied to program awards and thus free up additional funding for rural veterinary care, so the program can serve more rural communities without expanding its budget footprint. This legislation is a common-sense solution to a MeV serious problem, according to the AVMA. ModernEquineVet.com | Issue 4/2019
Several of the largest American race tracks said they would phase out the use of furosemide, which is commonly used on race day, beginning in 2020. By 2021, furosemide will be banned for all major races, including the Triple Crown. These tracks stage about 86% of the U.S. stakes races, including the Triple Crown Kentucky Derby, Preakness Stakes and Belmont Stakes. This industry-led initiative successfully gained approval on these reforms from California’s regulatory body for horse racing, the California Horse Racing Board (CHRB). All tracks owned or operated by Churchill Downs Inc., the New York Racing Association Inc. and the Stronach Group, as well as Del Mar, Keeneland, Lone Star Park, Remington Park, Los Alamitos Racecourse, Oaklawn Park and Tampa Bay Downs will be affected by this ban. Other groups, including the Breeders' Cup Limited, the Thoroughbred Owners and Breeders' Association and the Kentucky Thoroughbred Association also support this new policy. The proposal calls for banning furosemide for all 2-year-old horses within 24 hours of
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a race beginning Jan 1, 2020. All other horses would be affected beginning in 2021. “Horse racing in the U.S. faces significant challenges to its long-term health. The leadership of the American Association of Equine Practitioners (AAEP) reviews with interest the announcement by a cohort of Thoroughbred racing organizations that they will ban the use of furosemide in 2-year-old racing in 2020 and graded stakes races in 2021. The landscape is changing,” said AAEP President Jeff T. Berk, DVM, of Equine Medical Associations of Lexington, Ky. “As doctors of veterinary medicine, science and evidence-based discovery is our foundation, and as such, the AAEP’s long-standing racehorse medication policy has supported the administration of furosemide on race day to mitigate the adverse effects of exercise-induced pulmonary haemorrhage (EIPH),” he said in a statement. Belinda Stronach, chairperson and president of The Stronach Group said the development of this policy was not easy. “We are on track to be aligned with medication standards consistent with, or more restrictive than, those of the International Federation of Horse Racing Authority, which are the world’s benchmark for horse safety and welfare. “While we have paved the way in working with the Thoroughbred Owners of California and the CHRB to make changes here in the state, national collaboration is necessary in order to truly evolve the sport,” she said. “The desire to achieve uniform policies is the beginning of a movement that will redefine the expectations and views on safety within our sport.” The AAEP said it would fund research to find an alternative for current EIPH management strategies, according to Dr. Berk, which could eliminate the need for furosemide. “The proposed phase-out of the medication’s use beginning at many Thoroughbred racetracks in 2020 emphasizes the urgent need for continued research into new methods for mitigating EIPH. “Regarding the daily care of horses adversely affected by EIPH, the AAEP urges a strong partnership between owners, trainers and veterinarians to optimally manage the syndrome and make decisions in the best interest of the health and welfare of the horse,” he said. Many racing jurisdictions around the world already ban the use of furosemide, commonly called Lasix, which is used to prevent pulmonary haemorrhages during races. MeV
Shutterstock/Sara Julin Ingelmark
Thoroughbred Racing Announces New Restrictions on Race-Day Furosemide Use
The Dynamics of Dynamic Respiratory Endoscopy By Elyse Rowley, MS Riviera Equine is a mobile internal medicine practice. Being mobile is clearly different from being in a hospital setting but being a small, niche practice allows us to tailor our services to the needs of our clients and patients. Repeatedly, our clients described a respiratory noise that their horse was making under saddle during work, but they’d had a standing scope and their veterinarian was not able to see the cause of the noise. We heard this same complaint often enough to bite the bullet and purchase a dynamic respiratory endoscope to help more of our patients. Some of the cases we see are first opinion and some are referrals but in every case we onsider the client, the horse, and its signs to decide whether it is suited for a dynamic scope. Some of these considerations include the description of the complaint or noise, the temperament of the patient (Can we physically get the scope up their nose without sedation?) and will the owner or trainer be comfortable riding the horse once the DRS is in place. The horse has to have the right temperament to tolerate the scope while being ridden. We have now used the dynamic scope on many breeds performing a variety of work and have been pleasantly surprised and impressed by how well horses and ponies tolerate this. To date, we’ve only had one patient that we were unable to get the dynamic scope into, and luckily, we were able to finally get him sedated and still make a diagnosis with standing endoscopy. Here are a few specific cases.
including laboratory results, a verbal report of the standing endoscopy and a description of what the pony was doing from both the referring veterinarian and the trainer. We also received video footage of the pony under saddle with an audio clip so we could hear the noise it was making. During the appointment, we ran through the history again and performed a standing endoscopy of both the upper airway and the guttural pouches—because the guttural pouches had not been visualized on the initial scope. We didn’t find anything that gave us an answer either so we fitted him up with the dynamic scope. His standing endoscopy exam was within normal limits. He had good tone to his epiglottis and his arytenoids were abducting fully with inspiration giving him a good, open airway. As horses and ponies are warmed up, we check the placement once or twice then turned them loose to do their thing. Both inspiratory and expiratory noises were audible while he was at work with his head in a collected position. Frequent dorsal billowing of the soft palate—which obstructs the view of the rima glottis
A 14-year-old youth’s hunter pony presented with a complaint of “respiratory noise under saddle with excessive mouth gaping and tongue movement during work.” In this case, the pony was referred by another veterinarian who’d already performed a standing scope and reported no abnormalities. Prior to meeting the pony, Phoebe Smith, DVM, DACVIM (LAIM), the owner of the practice, obtained a full medical history,
Photo courtesy of Eylese Rowley
Dynamic scope ModernEquineVet.com | Issue 4/2019
Photo courtesy of Eylese Rowley
Working horses with the dynamic endoscope in place.
and significantly obscures the pony’s airway—appeared to be the cause of the noise and the pony’s distressful signs, such as excessive mouth gaping and tongue movement. He is not displacing his epiglottis and his arytenoids are opening fully and symmetrically but the soft palate obstructs his tracheal lumen every time it billows. His diagnosis was palatal instability or soft-palate billowing. This instability was repeatable at a walk, trot and canter with his head position directly affecting the frequency and prominence of the billowing and subsequent obstruction of his airway. Possible causes of palate instability include poor fitness or guttural pouch disease with resulting cranial nerve inflammation. You may recall that we redid
Teaching Points The biggest limitation that we’ve run up against so far is duplicating the environment where the patient makes the noise. We’ve had a few cases where the horse only makes the noise at the highest level of competition—during a jump off for the championship for example—and we just can’t duplicate that environment or level of stress/ anxiety/excitement/what-have-you. Whether we see the horse or pony on first opinion or on referral, we’ve gotten to see a lot of neat cases and use the dynamic scope in a wide variety of disciplines. Not all of our diagnoses are fixable, but most clients are happy to finally have an answer, whether or not it is something that we can treat or surgically repair.
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his standing scope specifically to evaluate his guttural pouches, and they were clean. The pony also was at an appropriate level of fitness, so we could rule out poor fitness, nor was there a surgical fix for this problem. This left us with changing his bitting and allowing him to carry his head in a position that worked for him. Unfortunately, the head position that works best for him isn’t a perfect show hunter head set. The initial follow-up with the trainer after his diagnosis and subsequent recommendations was that she was seeing positive results with removing the bit and flash, and altering his head position.
The second case was a 3-year-old Thoroughbred filly that looked to have a promising race career until she started coming in second in every race. She’d break from the starting gate well, run great, be well in the lead and then just before the finish line, she’d “choke down” and get beat at the wire. In slow motion review of her dynamic scope, the filly had “laryngeal collapse” or, more specifically, an axial deviation of her aryepiglottic fold, vocal cord collapse and left corniculate process collapse. In this particular case, the farm chose to retire and breed the mare, hoping to reproduce her speed and talent but not her throat function. Next we have an 8-year-old Warmblood gelding that was referred for dynamic endoscopy due to a recent cough and a long-term reluctance to work, although he has competed and won at the highest
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Photo courtesy of Elyse Rowley
Testing horses with dynamic endoscopy.
We purchased a dynamic endoscope because we could not always determine the cause of respiratory noise with a standing endoscope.
level as a hunter. In stepping through his long history, it sounded as though his primary issue was incompletely controlled inflammatory airway disease (IAD), but the trainer was very insistent that he needed a dynamic scope, so we performed one to make sure we weren’t missing anything else. His standing endoscopy revealed mucus in the proximal trachea and a flaccid epiglottis, while his guttural pouches were normal. Dynamic endoscopy showed transient left vocal fold axial deviation, slight billowing of the soft palate without dorsal displacement or obstruction of the airway and excess mucus production. The persistent and excessive mucus supported the initial theory that his IAD was simply uncontrolled as the other minor abnormalities noted with the dynamic scope weren’t in any way significant enough to cause the presenting complaint. In this case, the bronchoalveolar lavage (BAL), rather than the dynamic scope gave us the diagnosis.
Another Warmblood gelding, this time a 5-year-old used for dressage, again presented with a complaint of “noise.” We started with a standing endoscopy and 16
Issue 4/2019 | ModernEquineVet.com
found that he had left laryngeal hemiplegia or as it’s more commonly known, he was a roarer. What made this case interesting was that the owner was still interested in performing the dynamic scope to see what his throat looked like under work and while his head was collected. As it turned out, the diagnosis didn’t change, but our appreciation of the severity of his condition did. With dynamic endoscopy, we could see that his left arytenoid sucked down across the tracheal lumen, obstructing his airway. Dr. Smith had initially graded him at a 2 with standing endoscopy, but increased him to between a 3B and 3C under work. His owner opted to have a tie back surgery performed based on the severity of his condition while at work and the fact that the noise is a detriment for a dressage horse. MeV
About the Author
Elyse Rowley, MS, is the assistant to Dr. Phoebe Smith, the owner of Riviera Equine Internal Medicine and Consulting, a mobile specialized internal medicine service for horses in the Santa Ynez Valley, Central Coast and Southern California regions.
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