Guttural Pouch Tympany

Amanda Leferink Hoffpauir

Just what are the guttural pouches? What does it mean when my veterinarian tells me my foal has guttural pouch tympany?

The auditory tubes connect the middle ear to the throat and allow the air in the middle ear to equilibrate with the pressure of the external air. Equines have special dilations of these tubes called guttural pouches. The guttural pouches are located just behind and above the pharynx, the area where the oral cavity, nasal cavity, trachea, and esophagus come together. There are two pouches, one on each side of midline.

When the guttural pouches become abnormally distended with air, the condition is referred to as guttural pouch tympany. This uncommon condition occurs in foals and is usually caused by a malformed guttural pouch opening. The opening, instead of allowing air and mucus to move freely in and out of the pouches, acts as a one-way valve, trapping the air and mucus inside. Guttural pouch tympany usually occurs on only one side, but it may occur in both at the same time. By trapping mucus inside the pouches, tympany can lead to guttural pouch empyema, a bacterial infection of the guttural pouch. Guttural pouch enlargement puts pressure on the esophagus and trachea, making it difficult for the foal to swallow and breath. This can lead to aspiration, or inhalation, of milk or feed as the foal tries to swallow, which can in turn lead to pneumonia.

Diagnosis of guttural pouch tympany is fairly straightforward. The foal will have a swelling in the throatlatch area that is slowly getting larger. Percussion of the area will suggest that it is filled with air. Your veterinarian will want to take radiographs of the throatlatch area to confirm guttural pouch tympany and rule out other causes of guttural pouch enlargement, and radiographs of the chest to be sure that the foal does not have pneumonia. Foals with uncomplicated guttural pouch tympany will be alert and have normal heart and respiratory rates. If the tympany is complicated by pneumonia or empyema, the foal may have increased heart rate, increased respiratory rate, nasal discharge, fever, decreased appetite, or coughing.

Treatment of guttural pouch tympany results in immediate improvement. The pouches may be deflated temporarily by placing a tube into the opening of the affected pouch, or placing a hypodermic needle through the neck into the pouch. These treatments are only temporary, however, and the pouch will slowly refill with air as soon as the tube or needle is removed. Permanent correction of guttural pouch tympany requires surgery, the type of surgery depends on whether one or both pouches are involved. For all guttural pouch surgeries, the foal is placed under general anesthesia. If only one pouch is involved, an endoscope can be passed through the opening of the normal pouch. A laser is then passed through the endoscope and a hole is cut between the two pouches, allowing air from the abnormal pouch to exit through the normal pouch. Alternatively, an incision may be made in the neck, allowing the surgeon to enter the affected pouch and cut a hole into the other pouch for air to escape. This method has the benefit of allowing the surgeon to gain access to the inside of the pouch and clean out any mucus and pus that may be there. If both pouches are affected, the surgeon will make an incision into the neck and enter the pouches. Then, it is possible to enlarge the natural opening of one or both pouches into the pharynx and allow the air to escape.

Recovery from uncomplicated guttural pouch tympany is rapid and complete. Aspiration pneumonia and guttural pouch empyema, if they are present, will take much longer to resolve and will require administration of appropriate antibiotics and supportive care.

Ask your veterinarian to examine any swelling in the throatlatch area of your foals. Guttural pouch diseases can be prolonged, more costly to treat, and result in secondary complications, such as aspiration pneumonia, if left untreated. Early treatment gives your foal the best chance for rapid, complete, uncomplicated recovery.