Monday, January 21, 2008
We seem to have had a run on laryngeal disease over the last month so I thought i would post a quick tutorial. Horses can get a variety of Laryngeal diseases, including arytenoid paralysis, ulcers,
neoplasia, epiglottic displacement, epiglottic entrapment and sub-epiglottic cysts.
This is a normal view through a fiber optic endoscope. What you see is epiglottis in the foreground that looks like a pointed tongue. behind this are the arytenoids that work like curtains covering the opening to the trachea.
In this horse you can see the left arytenoid is hanging down into the airway. This is an example of Laryngeal paralysis. Frequently this is caused by damage to the left recurrent laryngeal nerve. It can also be related to damage to the arytenoid itself such as infection of the cartilage.
This is what typically is known as roaring, when the horse makes a respiratory noise (usually on inspiration) while working.
This is a picture of an arytenoid ulcer.
It is actually one that is healing after having had a draining tract for several weeks.
In this case the left arytenoid was so
thick and edematous that it caused it
to hang into the airway causing a respiratory noise. It eventually led to a left laryngeal paralysis.
The treatment for this condition is the surgical tie-back where the left arytenoid is sutured back out of the airway. This will allow for adequate inflow of air during exercise and lets the horse perform at near normal levels. the down side to having this done is that the airway is now 50% open ALL the time. This means that they are more prone to tracheal and pulmonary infections and irritations from dust and debris. Another point to be made is that this will NOT eliminate the noise , which means that certain show horses will still be knocked back for respiratory noise.
Should you have a horse that makes a noise or has a performance issue that could be respiratory in origin then you should have an endoscopy done on your horse. It is simple and relatively non-invasive and can give you a wealth of information.