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Commercially available overground endoscopes allow veterinarians to evaluate horses in their normal work conditions, including the impact the rider or driver has on the horse’s performance.
Photo: Anne M. Eberhardt/The Horse
Norm Ducharme, DVM, MSc, Dipl. ACVS, recently joined the elite group of equine veterinary specialists invited to share their careers’ culminations during the Frank J. Milne State-of-the-Art lecture, held annually at the American Association of Equine Practitioners Convention. Ducharme, renowned for his work in equine upper respiratory disease diagnoses and treatments, described both tried-and-true approaches to managing upper airway disease as well as novel approaches currently under investigation. Ducharme currently holds the position of James Law Professor of Surgery in the Section of Large Animal Surgery at the Cornell University Hospital for Animals, in Ithaca, New York. He is also a staff surgeon at Cornell Ruffian Equine Specialists, in Elmont. He gave the address during the latest edition of the convention, held Dec. 3-7 in Orlando, Florida.
Ducharme began his presentation with a brief review of some important basics:
- The equine upper respiratory tract consists of all respiratory structures from the nose to the extrathoracic trachea, including the larynx and associated structures;
- Upper airway obstruction can negatively impact a horse’s athletic performance as well as quality of life; and
- Abnormal airflow patterns can result in upper respiratory noise; however, the intensity of such noises does not necessarily correlate with the degree of airway obstruction.
“Horses faced with impaired ventilation use one of three strategies to compensate: increasing the driving inspiratory pressure, uncoupling … gait and respiratory frequency, or changing the duration of inspiratory and expiratory times,” Ducharme said.
Those strategies ultimately manifest as the two leading clinical signs suggestive of upper respiratory disease: poor performance and abnormal respiratory noise.
Diagnosing Airway Obstruction
When assessing a horse with suspected upper airway disease, Ducharme reminded attendees that 30-43% of horses have multiple impediments, which he referred to as comorbid (caused by one or more concurrent diseases) obstructions, and that low circulating oxygen levels (called hypoxemia), due to either lower airway disease (of the structures beyond the extrathoracic trachea) or cardiac disease, can also contribute to upper airway obstruction.
Indeed, respiratory noise is often a tipoff that something is awry in the airway. Many horses with dorsal displacement of the soft palate (DDSP, abnormal upward deviation of the roof of the mouth, usually occurring intermittently during work) make a gurgling noise on exhalation, and horses with left laryngeal hemiplegia (roaring, in this case caused by paralysis of the nerve controlling the left laryngeal cartilage) tend to make a roaring sound on inhalation.
“The absence of noise, however, does not mean that the horse in question has a fully patent (unobstructed) airway,” Ducharme said. “Respiratory noises simply suggest a cause of the abnormal sounds but are not a complete indicator of the full spectrum of airway compromise or to be used to decide if surgery is needed or not.”
Considered a neat new toy only a few years ago, overground endoscopy—that is, the assessment of the horse as it is working under saddle or in harness, aka dynamic endoscopy—is now the “gold standard” for diagnosing upper respiratory abnormalities. This holds particularly true in sport horses, where recreating poll flexion can help the veterinarian diagnose airway obstruction that might not be evident on resting endoscopy.
Physical Findings Supporting Airway Obstruction
Ducharme reiterated that any abnormality of the airway and associated structures can cause obstruction—there’s more to consider than just the “classic” diagnoses of DDSP or laryngeal hemiplegia. Detecting any of these begins with a basic physical exam.
For example, drainage from the nasal cavities, facial swellings caused by masses/enlargement of the sinuses, or asymmetrical airflow through the nostrils are other possible issues veterinarians catch. Further, veterinarians can pick up on subtle signs associated with Horner’s syndrome—pathology (damage or disease) of the head’s sympathetic nerve supply, which results in failure of the nervous system to control nerves and associated muscles and organs. Ducharme said horses with Horner’s syndrome have ptosis (a drooping upper eyelid) and third eyelid prolapse, both of which can be subtle.
“In my experience, abnormal vertical position of the eyelashes compared with the normal, contralateral side frequently helps diagnose Horner’s syndrome in horses,” he said. “If one sees that, then pay particular attention to check if airflow is also reduced which would/could affect prognosis.”
Next, the veterinarian should palpate the laryngeal cartilages to check for any obvious malformations or cysts. He said the jugular veins also need to be assessed to ensure there’s no evidence of thrombophlebitis (vein inflammation and blockage). Thrombophlebitis can occur in concert with injury to the vagus nerve (the longest nerve extending from the brain) and recurrent laryngeal nerve and potentially contributes to airway obstruction, as both those nerves supply important structures in the equine respiratory tract.
Ducharme said practitioners can also identify atrophy (wasting) of the cricoarytenoid dorsalis (CAD), a small but mighty muscle serving as a major abductor of the larynx, via routine physical examination.
“Generic” and Advanced Diagnostic Testing of the Equine Airway
Although he referred to it as a generic approach, Ducharme emphasized the importance of resting endoscopy (or “scoping”) when assessing upper airway patency and searching for abnormalities.
“Sedating the patient for resting endoscopy may interfere in the evaluation of laryngeal function,” he said. “In my experience the nasal passages, nasopharynx, and larynx are best examined with the animal unsedated to avoid a false diagnosis of nasopharyngeal collapse or recurrent laryngeal neuropathy.” (Neuropathy is disease or dysfunction of one or more peripheral nerves that typically causes numbness or weakness.)
Conditions veterinarians can easily diagnose during resting endoscopy include:
- Masses and cysts;
- Arytenoid chondritis (inflammation of the cartilages);
- Persistent dorsal displacement of the soft palate (pDDSP);
- Epiglottic abscesses; and
- Guttural pouch empyema (pus collection), mycosis (fungal disease), and tympany (swelling from air accumulation).
With guttural pouch diseases, the vagus and glossopharyngeal nerves running through the medial compartment (that is, the larger of the two segments of the guttural pouch) can become inflamed or even paralyzed, resulting in nasopharyngeal collapse and pDDSP.
“Caution must be used when using resting endoscopy to diagnose intermittent DDSP because even with a history of noise during exercise, studies show that veterinarians only correctly predict intermittent DDSP (iDDSP) in 50% of cases,” said Ducharme. “Even identification of an ulcer on the caudal free edge (back) of the palate, a flaccid epiglottis, and induction of DDSP by either swallowing or nasal occlusion are not reliable indicators of iDDSP.”
If a horse has an ulcer on the caudal free edge of the soft palate, he might have a subepiglottic ulcer/granuloma or intermittent epiglottic entrapment—when the loose skin located on the bottom of the epiglottis (hence, sub-) flips over, covering the epiglottis like a slipper.
Based on Ducharme’s comprehensive review of the available literature, he deemed resting endoscopy an appropriate diagnostic technique for laryngeal hemiplegia. Primarily caused by neuropathy of the left recurrent laryngeal nerve, roaring occurs when the left arytenoid cartilage droops into the airways at the entrance to the trachea (i.e. voice box). Ultrasound examination of the muscles associated with laryngeal function also appears to be highly valuable; however, ultrasound should not replace resting endoscopy, he said, because other obvious lesions can easily be missed. Examples include arytenoid chondromas (rare benign cartilaginous tumors) and subluxations (partial dislocation), abnormal movements of the arytenoid cartilages, inflammation of the epiglottis (called epiglottitis), epiglottic abscess, and subepiglottic ulceration.
While Ducharme focused heavily on athletic horses during his lecture, he noted that airway issues also affect swallowing. As such, even nonperformance horses and foals benefit from endoscopic airway evaluations, particularly in cases of swallowing disorders or dysphagia (difficulty swallowing).
Returning to the main focus of his lecture, Ducharme described the merits of dynamic endoscopy testing both for recognizing collapse while the horse is exercising and confirming the absence of airway obstruction. Veterinarians traditionally performed such dynamic endoscopy using a high-speed treadmill that assured horses reached at least near-maximal exercise intensity. Now, commercially available overground endoscopes allow veterinarians to evaluate horses in their normal work conditions, including the impact the rider or driver has on the horse’s performance.
“I prefer overground endoscopy for sport horses in which head position and poll flexion collections impact the examination,” Ducharme said. “Overground endoscopy is also preferred in Thoroughbred racehorses; however, trotters and pacers have a higher prevalence of coexisting morbidity (illness) that often requires additional testing, making high-speed treadmill endoscopic examinations preferable.”
Ducharme’s lecture notes in the AAEP Convention Proceedings include details regarding grading of DDSP and laryngeal dysfunction using resting endoscopy. For roaring, Ducharme’s grading scale of choice is a 4-point scale with various subgrades adopted during the Havemeyer Workshop on equine recurrent laryngeal neuropathy held in September 2003. He also briefly touched on additional diagnostics, such as radiography, ultrasound, computed tomography, and MRI, and pros and cons of each.
Managing Upper Airway Disease
Armed with an array of videos and still images of various patients he’s evaluated, Ducharme polled the attendees using interactive technology via their smartphones: What is the diagnosis, and does this horse need surgery? If so, what are potential treatment options? Audience members could also submit questions, which appeared on the screen in the session room for all to discuss.
Ducharme presented a variety of conditions and described management strategies for each.
DDSP Management Options
A surgeon at heart, Ducharme recommended surgery for horses with iDDSP … but only after medical therapy and tack modifications in already-fit horses have failed. Possible medical therapies and tack modifications include systemic anti-inflammatory medications such as dexamethasone or prednisolone, tongue ties, bit changes (try the “W” or Serena Song bits), bitless bridles, and figure-eight or dropped nosebands.
Also, it’s important that young horses have been allowed to mature in case they are simply suffering from an “immature nasopharynx.”
“Several surgical options for iDDSP exist, but many have been devised without a clear understanding of the underlying condition,” Ducharme said.
Current surgical strategies include the following, each associated with its own benefits and weaknesses:
- Correcting underlying issues to relieve iDDSP (removing granulomas, cysts, and abnormal subepiglottic tissue);
- Increasing the stiffness of the soft palate (using cautery, laser, or chemical agents to potentially decrease palate fluttering); and
- Altering the larynx’s position to limit the soft palate’s movement (strap muscle resection, or bilateral partial stenothyroidectomy,) and/or tie-forward surgery.
Typically, bilateral stenothyroidectomy and/or a tie-forward procedure is the preferred surgical procedure, he said. Success ranges from 58% to82%.
The underlying cause of roaring remains unclear. Attempting to force the arytenoid cartilage from blocking air passage through the larynx and into the trachea, surgeons frequently turn to laryngoplasty—also called a tie-back procedure—in conjunction with removal of the vocal cords and folds (ventriculocordetomy).
The tie-back itself involves physically pulling the flaccid cartilage out of the airway using permanent suture material. Success with this procedure, like iDDSP, leaves us wanting for more, he said, and “DDSP is a newly recognized complication seen after laryngoplasty.”
For details and treatment recommendations for DDSP, laryngeal hemiplegia, and other upper airway conditions, refer to the full-length article in the Convention Proceedings. He also described complications and the methods for determining causes of persistent upper respiratory noise and poor performance following surgery. He also described more novel methods of managing roaring in the Proceedings, including laryngeal reinnervation and electrical rehabilitation of the CAD muscle.
Ducharme wittingly reminded attendees that the upper airway crosses the finish line first and, in his opinion, is the most important anatomic region of the horse. Despite dedicating his career to conditions adversely affecting equine upper airways, little “Level 1 evidence-based data” and few meta-analyses currently exist to help guide veterinarians in managing airway disease. Ducharme emphasized that the treatment goal of any airway abnormality should be based on the most up-to-date literature and be the least-invasive approach that results in a quick return to function.
About the Author
Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she’s worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.
|March 18 – Santa Anita|
|Ocean Dream||Wgt-118||Race 1||Maiden Special Weight|
|Road Test||Wgt-120||Race 3||Maiden Special Weight|
|Smoove It||Wgt-120||Race 7||Irish O’Brien S.|
|Lady Tapit||Wgt-120||Race 9||Santa Margarita S. (Gr 1)|
|I’d Be Sad an Blue||Wgt-123||Race 10||Maiden Special Weight|
|March 19 – Santa Anita|
|Green With Eddie||Wgt-124||Race 3||Allowance Optional Claiming $75,000|
|Sir Studleigh||Wgt-126||Race 5||Maiden Special Weight|
|March 17 – Santa Anita|
|Paynes Prairie finished 7th beaten 7 3/4 lengths||Race 5|
When Bob Baffert sends his top-caliber horses to compete in Oaklawn’s stakes program, he contracts with top-notch local help to get them ready for race day. Exercise rider Jody Piper has been aboard all of the Hall of Fame trainer’s horses- except one. That one just happens to be none other than American Pharoah.
“I’ve been galloping for 40 years and got on all of them from Baffert, all of those Rebel and Arkansas Derby winners, but I missed the Triple Crown winner,” said Piper, who has also spent the afternoons working as a valet in the jockeys’ room for 35 years. “That would be a gallop boy’s lifetime dream, to get on a horse that wins the Triple Crown. How often does that happen?
Not very. American Pharaoh, winner of the 2015 Rebel Stakes and Arkansas Derby winner, was the first Kentucky Derby, Preakness Stakes and Belmont Stakes winner in 37 years and went on to capture the Breeders’ Cup Classic and Horse of the Year honors.
With Piper having a “regular” job that year with the local manufacturer of the Baggo and Cornhole games, Oaklawn-based trainer Mike Johnson got the assignment to gallop American Pharoah before the Rebel and Arkansas Derby.
“Timing is everything and you have to be lucky. Mike was the lucky person who got on him,” Piper said.
Piper was eventually laid off from his job off the racetrack and once he came back to Oaklawn, one of the first calls he made was to Jimmy Barnes, Baffert’s longtime assistant who has been bringing the barn’s horses here for at least 15 years by his account.
“I said I’d love to come back and he said I’d love to have you on our horses,” he said Friday morning after taking American Anthem and stablemate and Essex Handicap morning favorite Mor Spirit for their last etrips around the oval before their races.
Piper had only high praise for American Anthem, the 2-1 morning line favorite for the Rebel. The colt is a son of 2012 Arkansas Derby winner Bodemeister, who had a well-earned reputation as a handful.
“I galloped his daddy, Bodemeister, and he won the Arkansas Derby by 10 [9 1/2] lengths,” Piper said. This horse feels really good. He goes over the track beautiful, just beautiful. He’s got nice motion, nice action, and a big stride. He’s effortless going over the track. He’s very intelligent, too. The first day we got up there it was a little early and there was a crowd, a lot of action, a lot of noise and a lot of horses working. There were horses coming on both sides of him, and he just went about his way. Nothing has phased him. From the way he acted out there, I couldn’t believe this horse has only run twice,” said Piper.
Hall of Famer Mike Smith handles the afternoon assignment on American Anthem on Saturday. But he and Piper won’t need to be introduced.
“Mike was my first jockey when I started as a valet way back,” said Piper, who will assist Smith, Gary Stevens and Victor Espinoza when they are here to ride on Saturday as well as his regular Oaklawn jockeys Luis Contreras, Joe Rocco, Jr. and Ramon Vazquez. “I was his best man when he got married.”
After two wins at Gulfstream Park by a combined 22 lengths, Malagacy was pinned with the rising star tag in Todd Pletcher’s barn full of Triple Crown hopefuls. Entering the Rebel Stakes, not even the chestnut colt’s seven-time Eclipse Award-winning trainer knows how good he may be.
“He’s been a pleasant surprise and he has certainly run impressively,” Pletcher said from his South Florida base. “We’re optimistic and I guess we’ll know for sure pretty quickly.”
Malagacy, who comes in to the Rebel as the 4-1 second choice on the early line and will break from Post 6 under multiple Eclipse Award-winning rider Javier Castellano. He has yet to race beyond 6 1/2 furlongs, but he is a son of 2011 Preakness Stakes winner Shackleford out of a Dehere mare so his pedigree top and bottom suggests he’ll handle the 1 1/16 mile distance of the Rebel. He fired a bullet 5 furlong work of 1:01 at Palm Beach Downs March 11 before getting on a plane from Florida.
“His works have been quite good when going with horses, who are proven around two turns,” Pletcher said. “He has a good disposition so I think he’s rateable and that gives us the optimism that he’ll stretch out. He’s a very kind horse and he’s easy to ride. We’ve set him behind horses in the mornings and that doesn’t seem to bother him. Obviously, he has natural early speed, but I don’t think he’s headstrong. I think he’ll allow Javier to ride him accordingly.”
With an 11-horse field and plenty of speed in the race, it’s a given that the pace will be quite lively in the early going.
“We’re going to let him run his race and not worry about what anybody else does,” Pletcher added, while noting that Malagacy was assigned seven pounds less to shoulder than 122 lb. co-highweights Royal Mo and Uncontested. “We’ll let him get into a comfortable rhythm wherever that is. But I don’t envision him being too far off the pace. He’s stretching out for the first time and he’s got plenty of speed, so we’ll see how the race unfolds and let Javier (Castellano) figure it out into the first turn.”
Although Malagacy has yet to earn any Kentucky Derby qualifying points and there are 50-20-10-5 (1st through 4th place finish) available, Pletcher wasn’t looking down the road to Louisville.
“We’ll take it one step at a time and one race at a time,” he said.
Malagacy, who was purchased at auction for $190,000 by Sumaya US Stables as a 2-year-old, is believed to be named for the Malagasy ethnic people who comprise almost the entire population of the island nation of Madagascar and the language they speak, despite the different spelling of the word.
Petrov galloped 1 7/8 miles just after the track opened Friday morning for co-owner/trainer Ron Moquett of Hot Springs in preparation for the $900,000 Rebel Stakes (G2) for 3-year-olds Saturday at Oaklawn.
Petrov has finished second in his last two starts – both under New York-based Jose Ortiz – the $150,000 Smarty Jones Jan. 16 and $500,000 Southwest Stakes (G3) Feb. 20. He was in chase mode in both starts this year, but Moquett said he hopes for different tactics Saturday.
“I just want a nice smooth trip,” Moquett said Friday morning. “Jose’s good at getting us in position, so I want us in position to get the most out of him. We’re going to place ourselves in position to win the race.”
Moquett said he and co-owner Catherine Adams Hutt, previously 50-50 partners, now own 75 percent of Petrov after recently selling a 25- percent stake in the Flatter colt to Sol Kumin.
Royal Mo galloped a mile before the renovation break Friday morning in preparation for the Rebel, which will mark his first start outside California.
“Before the rain,” trainer John Shirreffs said, alluding to sprinkles falling outside the Davona Dale barn. “I should say today, before the parade.”
The First Ever 14th annual World’s Shortest St. Patrick’s Day Parade was to be held later Friday in Hot Springs.
“There’s a lot going on,” Shirreffs said. “You used to have, what, the gangsters here? Now, you’ve got the Irish.”
The Southern California-based Shirreffs will be looking for some luck with Royal Mo, the first 3-year-old the trainer will start at Oaklawn. The son of champion Uncle Mo, finished second in his first two career starts sprinting before stretching out to break his maiden at a mile and winning the $150,000 Robert B. Lewis Stakes (G3) at 1 1/16 miles in his last start, Feb. 4 at Santa Anita.
Shirreffs said he believed Royal Mo would be more effective at longer distances. “He’s a big horse,” Shirreffs said. “Still growing and developing.”
Shirreffs has started seven horses at Oaklawn, including six in the Apple Blossom Handicap (G1) for older fillies and mares (the trainer won the race in 2008 and 2010 with superstar Zenyatta).
Shirreffs’ only other starter, Tiago, won the $500,000 Oaklawn Handicap (G2) in 2008. Zenyatta and Tiago were campaigned by Jerry and Ann Moss, who also own Royal Mo.
Lightly raced Silver Dust is doing well in advance of the Rebel, trainer Randy Morse said Friday morning. The colt is coming off a fourth-place finish in the $500,000 Southwest Stakes (G3) Feb. 20.
The Southwest was the first start around two turns for Silver Dust, who was also making his stakes and 3-year-old debut. It was his third career start.
Asked if he believed a possible faster pace Saturday would help Silver Dust’s chances, Morse said, “We’ll see.”
Morse trains Silver Dust, a gray son of Tapit, for prominent Texas automobile dealer Tom Durant, who purchased Silver Dust for $510,000 last year.
Uncontested will wear a tongue tie and a different type of bit in Saturday’s $900,000 Rebel Stakes (G2), trainer Wayne Catalano said Friday morning. He said the colt has been training in the new equipment after it is believed he suffered a breathing problem when he faded to sixth as the favorite in the $500,000 Southwest Stakes (G3) Feb. 20.
“We’re thinking he displaced,” Catalano said. “I think what we’ve corrected proved us right.”
Catalano was referring to a blistering 5-furlong work March 10 when Uncontested covered the distance over a fast track in :58.80 under regular rider Channing Hill and galloped out 6 furlongs in 1:10.60 and 7 furlongs in 1:24.80. He also recorded another 5-furlong bullet work (1:00) March 2.
The son of Tiz Wonderful, who races for Harry Rosenblum and Robert LaPenta, was a record-setting 5 1/4-length wire-to-wire winner of the $150,000 Smarty Jones Stakes Jan. 16 in his 3-year-old debut.
“He’s doing much better than he was,” Hill said following the March 10 breeze. “I told Harry these last two breezes were his best two breezes back to back. Now we’ve just got to translate that into the race.”