New approach to preventing choking or palatal displacement in the racehorse
What is the problem?
Choking or displacement of the soft palate towards end of a race is frustrating cause of poor performance in racehorses. The palate can either become unstable and billow or actually displace completely and block the airway. The horse usually slows significantly and makes a loud gurgling or choking sound. It is important to note that in 25% of cases no abnormal noise is heard.
How can a vet diagnose it?
It is tricky to accurately diagnose Displacing Palates as it only occurs during fast work or racing. The jockey and trainer information is the first piece of jigsaw.
Next scoping at rest is useful to rule out some other issues like laryngeal paralysis, epiglottic entrapment or other causes of obstruction. However, a resting scope cannot positively identify a Palate issue or a number of other concurrent issues such as aryepiglottic fold collapse, vocal cord instability and pharyngeal collapse. An endoscopic exam of upper airway during fast exercise is vital to identify the issues. This can be done with a dynamic scope with a jockey on the gallops or preferably on a high speed treadmill.
What training changes help prevent it?
Fitness and maturity: Unfit or young horses starting off in training are more likely to choke. Therefore, building strength and fitness will solve many cases. Two year olds and national hunt store horses who are gurgling during work often improve with time.
Tack: Badly fitting tack and certain bits aggravate the problem. Make sure teeth are rasped and try alternative bits such as spoon bit. A cross or dropped noseband to keep mouth closed is important.
Galloping head position: Jockeys should keep horse with an extended head position and to avoid any sudden changes in direction or speed. Some horses only gurgle when their head is being pulled in on pulling up which is not necessarily a problem
Tongue Tie: As the tongue is connected to the musculature at back of throat a tongue strap to stabilise its position sometimes helps. Make sure the horse is familiarised to it before racing and that it is not causing pain.
Going: The softer the ground the increased chance of horse displacing. Don’t train on too heavy sand but give horse confidence by training and racing on good ground.
Respiratory infections/allergies: Inflammation and mucus in the lower respiratory tract can contribute to horses displacing their palates. It can take horses a long time to recover lower airway function. Courses of nebulisation or oral prednisolone can help. Some horses benefit from being trained from the field.
Glycerine on tongue just before exercise helps keep seal with palate intact during exercise.
Established surgical interventions
As there are so many different causes and degrees of severity of Displacing palates there is no one surgical procedure that will work in every case. It is also a testament to how frustrating this conditions is to solve that there are numerous procedures ranging from cauterizing/firing palate, tie-forward operation, lasering palate, staphylectomy ( shortening palate), myectomy, tenectomy, Ahernes procedure, Teflon augmentation of epiglottis……..
At Troytown Grey Abbey Equine Hospital we prefer to do as little as possible to interfere with the structure of the throat as all of these procedures can have unwanted side effects. They also all leave an identifiable surgical scar and horses are all categorised as having had a wind surgery.
This aims to stiffen the palate tissue so it is less likely to billow and displace. It helps in just over half the cases by stopping choking completely or making it less likely. Sometimes it needs to be repeated every season.
Cutting the strap muscles and /or tendon where it inserts, prevents the larynx from being pulled into an abnormal position during exercise.
Two sutures are anchored in place with titanium buttons to pull the larynx closer to the thyroid bone. This changes the position of epiglottis making it harder for the palate to displace over it.
This shortens the palate which does not prevent it from displacing but causes less obstruction if it does.
Modified Aherne procedure / Oral Palatoplasty:
This is where a section of oral surface of palate is removed and stitched to tighten the palate.
All of these procedures can help prevent horses gurgling at work but none are guaranteed. Unfortunately, in some cases there can be side effects such as food coming down the nose and occasionally the surgery makes the condition worse.
They all require to be reported as surgical procedures.
In the last 18 months at TroytownGreyabbey we have been collaborating with a researcher in Kentucky on a new technique for stabilising palates.
It involves injecting a crosslinking agent ( Genipin) into the palate through an endoscope while the horse is sedated in stocks. It is quick and straight forward leaving no scar. In nearly 60 cases injected we have observed no adverse reactions apart from occasional temporary inflammation at injection sites.
Genipin is not classed as a medicine but as a medical device in the same way as bone cement and medical superglue are medical devices. It creates new cross links between collagen fibres thereby strengthening the tissues injected. This makes palates less likely to become unstable and displace above the epiglottis.
In just over 80% of cases treated there has either been a complete resolution of palate instability or a significant improvement. There have been a few incidents where a second injection was needed. There were still 20% of cases that not improve and these required a tie-forward or other surgical corrections. Even in these difficult cases it is our view that the Palatite provided increased stability.
Ideally we advise an exercise endoscopic assessment of the horses larynx to confirm diagnosis and discover any other concurrent problems. Without this it is possible that the incorrect treatment is given.
The horse is sedated and brought into standing stocks. A video endoscope is used to visualise the palate and larynx after being passed up right nostril. Local anaesthetic is sprayed onto the palate to numb it. Next the pre prepared injection is loaded into special syringes and a custom made transendocopic injection system is passed through to allow injection of Palatite into three locations on the palate. After the procedure the horse is given anti-inflammatory medication and once recovered from sedation can go home. The horse is led out for two-three days post procedure and usually can start light ridden exercise. Full training can commence after two-three weeks once there is no soreness.
Inserting Palatite into horse’s palates is a quick and simple procedure done standing in stocks.
After injection the horse has minimal time off before return to exercise.
There is no scar or evidence of surgical procedure.
It is an excellent first option for stabilising palates. It makes the palate more resilient to deformation. It is a more physiological procedure than cauterizing palates with either a hot iron or laser.
If there has been improvement after one injection but not completely resolved it is advisable to repeat procedure.
Approximately 15% of cases are too severely affected and these will require a tie-forward procedure.
All cases of DDSP in horses are different in both cause and severity. There is no one treatment that will solve every case. However even those cases that require further surgery palatite will contribute extra resilience and stability.
You can ask your own vet to contact us or if you’re already a client of Troytown GreyAbbey you can phone us anytime. Phone +353(0)45 521686
Soft Palate Modification Using a Collagen Crosslinking Reagent for Equine Dorsal Displacement of the Soft Palate and Other Upper Airway Breathing Disorders.
International Journal of Biomaterials Volume 2019, Article ID 9310890, 9 pages
Received 12 December 2018; Accepted 11 March 2019; Published 1 April 2019.
Stephanie Hunt,1 Jonathan Kuo,2 Fabio A.Aristizabal,3 Matt Brown,2 Abhijit Patwardhan,1 and Thomas Hedman
1,2 Biomedical Engineering Department, University of Kentucky, Lexington ,KY,USA 2Crosscoat Medical, LLC, ,KY,USA
3School of Veterinary Medicine, University of California-Davis, USA
Correspondence should be addressed to Thomas Hedman;email@example.com
Received 12 December 2018; Accepted 11 March 2019; Published 1 April 2019.