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Basics ⬇

Outline

BASICS

Overview!!navigator!!

  • GPs are diverticula of the auditory tubes that communicate with the pharynx. Infection within the GP causes accumulation of mucopurulent material (GPE)
  • Uni- or bilateral GPE often occurs secondarily to upper respiratory tract infection, abscessation, and rupture of the retropharyngeal lymph nodes into the GP

Signalment!!navigator!!

Affects horses of any breed, sex, or age.

Signs!!navigator!!

Historical Findings

  • Previous history of strangles
  • Chronic, mucopurulent nasal discharge of unknown cause

Physical Examination Findings

  • Unilateral or bilateral nasal discharge; may be abundant
  • Occasional swelling of adjacent lymph nodes
  • May present with cough, fever, difficulty swallowing, and/or breathing
  • Abnormal carriage of the head and neck
  • Empyema may occur without other clinical abnormalities

Causes and Risk Factors!!navigator!!

  • Frequently associated with Streptococcus equi var. equi and var. zooepidemicus
  • Infusion of irritants (therapeutics)
  • Congenital stenosis of the pharyngeal orifice of the auditory tube
  • Fracture of the stylohyoid bone
  • Pharyngeal perforation during nasogastric intubation

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

Differential Diagnosis!!navigator!!

  • GP mycosis
  • Trauma to GPs
  • Diseases causing mucopurulent nasal discharge (pneumonia, sinusitis)

CBC/Biochemistry/Urinalysis!!navigator!!

May be within normal limits; occasionally leukocytosis and fibrinogenemia.

Other Laboratory Tests!!navigator!!

Bacterial culture and sensitivity and cytology from GP aspirations or lavages.

Imaging!!navigator!!

  • Radiography of the pharynx—standing, lateral projection to identify a distinct fluid line
  • Ultrasonography—potential diagnostic value

Other Diagnostic Procedures!!navigator!!

  • Pharyngeal endoscopy to identify affected GP and intra-GP endoscopy to confirm the diagnosis
  • Passing of a sterile polyethylene catheter through the biopsy channel of the endoscope to collect samples for cytology and bacterial culture

Pathologic Findings!!navigator!!

Mucosal ulcerations with exudate accumulation, chondroids, and occasionally rupture and drainage of adjacent lymph nodes into the GP.

Treatment ⬆ ⬇

TREATMENT

  • Placement of an indwelling catheter to allow gentle irrigation of the GP with isotonic saline (500 mL) daily until debris no longer present
  • Avoid high-pressure/large-volume lavage to minimize risk of pouch rupture and the use of irritating solutions until debris is no longer present
  • Use of antibiotics based on bacterial culture and sensitivity results
  • Noninvasive methods for chrondroid removal include maceration, endoscopically guided grasping forceps, basket snare, or wire loop (best performed at a referral facility)

Medications ⬆ ⬇

Outline

MEDICATIONS

Drug(s) of Choice!!navigator!!

  • Antibiotics based upon bacterial culture and sensitivity results for a period of 10 days may be necessary
  • NSAIDs

Contraindications/Possible Interactions!!navigator!!

Avoid irrigation with irritating solutions such as a strong iodine solution and traumatic placement of the lavage catheter, which may cause damage to cranial nerves.

Follow-up ⬆ ⬇

Outline

FOLLOW-UP

Patient Monitoring!!navigator!!

  • Repeat endoscopy 1–2 weeks after the last irrigation therapy
  • Ground feeding to facilitate natural drainage
  • Provide appropriate care for dysphagic or dyspneic horses

Prevention/Avoidance!!navigator!!

  • Avoid exercise during treatment period
  • Biosecurity practices to prevent the introduction of strangles on a farm or to contain strangles once suspected/diagnosed
  • Vaccination protocols

Possible Complications!!navigator!!

  • Chondroid formation
  • Neurologic injury to the glossopharyngeal, vagus, accessory, and hypoglossal nerves

Expected Course and Prognosis!!navigator!!

  • Duration depends on the cause of the empyema
  • Prognosis is favorable with early diagnosis and treatment
  • Chondroids requiring surgical removal carry a poorer prognosis than medical treatment alone
  • Neurologic dysfunction carries a poor prognosis

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Associated Conditions!!navigator!!

  • Strangles
  • S. equi var. zooepidemicus sinusitis or laryngitis

Age-Related Factors!!navigator!!

Retropharyngeal lymph node abscessation due to strangles in foals and yearlings.

Abbreviations!!navigator!!

  • GP = guttural pouch
  • GPE = guttural pouch empyema
  • NSAID = nonsteroidal anti-inflammatory drug

Suggested Reading ⬆ ⬇

Freeman DE. Complications of surgery for diseases of the guttural pouch. Vet Clin North Am Equine Pract 2009;24:485–497.

Freeman DE. Update on disorders and treatment of the guttural pouch. Vet Clin North Am Equine Pract 2015;31:63–89.

Pascoe JR. Guttural pouch diseases. In: Smith BP, ed. Large Animal Internal Medicine, 5e. St. Louis, MO: Elsevier Mosby, 2015:555–558.

Author(s) ⬆

Authors: Mary Catherine Furness and Laurent Viel

Consulting Editors: Daniel Jean and Mathilde Leclère