Performance horses will sometimes develop a noise as they breathe while they are exercising, and this noise indicates abnormal air flow and decreased performance. For years, veterinarians have used endoscopes to place in the horse's nasal cavity and examine the structures in the nose and throat as the horse breathes. Many times it is possible to determine the cause of the abnormal noise using the scope when the horse is breathing normally at rest. However, a lot of horses are normal at rest and the source of the noise can only be diagnosed when the horse is exercising. Of course it is difficult to look in a horse's throat while they are running, so treadmills were used to run the horse while stationary so the vet could examine the horse's throat during exercise. The problem is that it takes a long time to train a horse to run on a treadmill and only a few facilities have treadmills.

In the last few years, a new technology has been developed called dynamic endoscopy. Dr. Canaan Whitfield-Cargille at Texas Equine Hospital indicates in the magazine of the Texas Equine Veterinary Association that this technology allows for a throat examination of a freely moving horse. The device contains a camera, a recorder is attached to the halter, and an endoscope is placed through the horse's nasal cavity. The horse is then allowed to exercise freely while the veterinarian watches the movements in the horse's throat either in real time or on tape. A recent study indicated that 82% of racehorses that were reported to make a noise during exercise were accurately diagnosed with this new dynamic endoscope. So if you have a horse that makes a noise only during exercise, consider this diagnostic procedure.