New Treatment for Tracheal Collapse

Two years later, Magnificent, a miniature horse, continues to do well with his intratracheal stent--the first ever implanted in a horse.

Magnificent suffered from tracheal collapse, an uncommon--and probably underreported--condition in which the
tracheal rings cannot maintain their shape, leading to a narrowed or collapsed tracheal airway. Tracheal collapse can be congenital or caused by a tumor, abscess, respiratory infection, or trauma. In mild cases, the airway obstruction can present as exercise intolerance--the horse tires quickly, breathes heavily, or coughs. In more severe cases, the horse has difficulty breathing even at rest, often emitting an abnormal respiratory sound. Diagnosis is based on a complete clinical examination, endoscopy, and radiography.

If left untreated, severe cases can become life-threatening. With treatment, prognosis ranges from excellent to poor, depending upon severity and underlying cause. The traditional means of correction is, after addressing any underlying problems, either removing up to five affected tracheal rings and replacing them with a small tube (after which the horse will have to wear a martingale to prevent over-extension of the neck and breakdown of the sutured trachea) or installing a prosthesis around the trachea to support the airway. However, both are involved procedures and are limited to the neck region of the trachea; surgical access deeper in the chest isn't possible.

After examining Magnificent, Laurent Couetil, DVM, Dipl. ACVIM, associate professor of large animal medicine and equine sports medicine director at Purdue University, determined that traditional surgical means weren't possible due to difficulty in the approach and risk of complications. After consulting a local pulmonologist, Couetil decided to use an endoscope to insert a tiny stent (a tube inserted into a passage to keep it open and prevent closure) to open and expand the trachea. In addition to allowing access into the collapsed area, the procedure was also far less invasive. "We placed the device with an endoscope, going in through the normal airways, from the nose down," Couetil says. "We didn't have to cut anything, there is no surgery, and the effect is immediate."

The procedure took 30 minutes. "He was able to breathe normally right after he recovered from anesthesia," Couetil says. "He was whinnying in a half hour; the owner had never heard him make a sound before."

The primary disadvantages to the intratracheal stent are cost and size of the horse. "These devices are human products," Couetil says. "The largest device on the market has a diameter of 2 centimeters and a length of 8 centimeters. An adult horse's trachea ranges from 3 1/2-6 centimeters in diameter, so this device can only be used in foals and miniature breeds. It is also an expensive procedure, although traditional surgery is expensive, too. The type of stent we used in our mini costs from $1,600-$1,800 per stent, not including procedural or implantation costs."

Couetil says the procedure is "promising" and "encouraging" for the appropriate candidate. "At this point, we don't have enough cases to definitively state what should happen," he says. "It appears that the outcome is guarded when very large portions of trachea are affected and too weak to sustain changes in air pressure during breathing or exercise; if you support one area, the areas next to it could collapse. But where small portions are involved, the device can relieve the obstruction and the airway before or after the device won't collapse.

"We need to have a better sense of how common tracheal collapse is and to develop guidelines so we can understand indications when we should use the device," he adds. "I don't believe this condition has been really well recognized, and there may have been a lot of animals that have been destroyed without considering these options."

About the Author

Marcia King

Marcia King is an award-winning freelance writer based in Ohio who specializes in equine, canine, and feline veterinary topics. She's schooled in hunt seat, dressage, and Western pleasure.

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