Guttural Pouch Anatomy, Problems Reviewed for World Equine Vets

Guttural pouches are more than just ill-defined air-filled vats located somewhere in the horse's head, said Julie Fjeldborg, DVM, PhD, an associate professor in the department of large animal sciences at the University of Copenhagen, Denmark, during the 11th Congress of the World Equine Veterinary Association, which was held Sept. 24-27, 2009, in Guarujá, Sao Paulo, Brazil.

Guttural pouches are of interest to both veterinarians and horse owners, as they contain a number of important structures. Arteries such as the internal carotid artery, and several cranial nerves, including the facial, glossopharyngeal, vagus, accessory, and hypoglossal nerves, also course through the guttural pouches.

Guttural pouch location

Location and anatomy of the guttural pouches (shown here in yellow).

The guttural pouches, unique to a limited number of mammals, such as the horse, rhinoceros, and the South American forest mouse, are paired diverticulae of the Eustachian tubes that connect the middle ear to the pharynx (which extends from the rear of the mouth and nasal passages to the larynx and esophagus ). Each guttural pouch has a volume of approximately 300 mL to 500 mL. The exact function of the guttural pouches remains elusive, even though scientists discovered them more than 200 years ago. One theory is that the guttural pouches serve as "brain cooling devices."

"It is important to note that the guttural pouches are not sterile. They contain the same bacterial composition as the pharynx," explained Fjeldborg.

According to Fjeldborg, since there is only very thin membrane (approximately 45 to 200 microns) that wraps around these delicate structures to separate potential pathogens or necrotic pus from major arteries and cranial nerves, it is clear that guttural pouch disease requires immediate treatment.

Some of the more common diseases of the equine guttural pouches include:

  • Empyema (the collection of pus);
  • Mycosis (fungal infection); and
  • Otitis media or interna (inflammation of the middle or inner ear).

When it comes to diagnosis of guttural pouch problems, the endoscope is the veterinarian's best friend. He or she can pass the scope via the nasal passages to access the guttural pouches where they communicate with the pharynx.

The veterinarian can also employ this tool when treat some guttural pouch diseases, conducting endoscope-guided flushes of the pouch(es) with a nonirritating solution for a minimum of seven days.

Fjeldborg noted other conditions of the guttural pouches might require more sophisticated treatment plans, including surgery or even embolization of the internal carotid artery to control bleeding in horses with mycotic infections. These cases require general anesthesia, fluoroscopy, and aggressive, long-term follow-up.

About the Author

Stacey Oke, DVM, MSc

Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she's worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.

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