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Basics ⬇

Outline

BASICS

Overview!!navigator!!

Nonpainful and tympanic swelling in the parotid and laryngeal region due to distention of 1 or both GPs with air. The enlarged GP may displace the pharynx, larynx, and trachea ventrally and to the contralateral side.

Signalment!!navigator!!

  • Observed only in foals and weanlings; most common between 2 and 4 months of age
  • Fillies are predominantly affected with a female-to-male ratio of 2:1 to 4:1
  • Most frequently reported in Standardbreds, Thoroughbreds, Arabians, Quarter Horses, Appaloosas, Paints, American Saddle Horses, and Warmbloods
  • A genetic predisposition has been reported in Arabian horses

Signs!!navigator!!

  • Nonpainful and tympanic swelling over the parotid region
  • In severe cases, stertorous breathing and dysphagia may develop
  • Secondary GP empyema and aspiration pneumonia are common findings
  • Unilateral involvement of the GPs is most frequently observed, although the parotid region is usually bilaterally distended

Causes and Risk Factors!!navigator!!

  • Exact etiology of the condition is unknown
  • It is considered to be a congenital dysfunction of the pharyngeal orifice of the affected GP

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

Differential Diagnosis!!navigator!!

  • Streptococcus equi infection (strangles) causing extreme swelling of the submandibular or retropharyngeal lymph nodes, retropharyngeal abscesses, and cellulitis is easily distinguished from GP tympany because these former conditions are associated with pain, fever, leukocytosis, and hyperfibrinogenemia
  • Primary GP empyema with Streptococcus zooepidemicus

CBC/Biochemistry/Urinalysis!!navigator!!

  • Stress leukocytosis may be present
  • Leukocytosis and hyperfibrinogenemia are found in the presence of aspiration pneumonia

Other Laboratory Tests!!navigator!!

N/A

Imaging!!navigator!!

Endoscopic Examination

  • Decreased airway size is observed when the nasopharynx and oropharynx are examined
  • Protrusion of either the roof alone or the roof and the wall of the pharynx on the affected side into the pharyngeal lumen is present
  • Introduction of the endoscope in the affected GP will deflate it and help to distinguish between unilateral and bilateral tympany

Radiography

  • Enlargement of air-filled GPs is noticed on lateral radiographic examination of the head and neck (rostral portion). With GP tympany, the affected pouch extends caudally
  • Collapse of the pharynx can also be noted

Thoracic Radiography

Rule out aspiration pneumonia.

Other Diagnostic Procedures!!navigator!!

Bacterial culture and antimicrobial sensitivity of fluid accumulated in the GP may be performed.

Treatment ⬆ ⬇

TREATMENT

  • External deflation of the GP by needle aspiration is not recommended because of the possibility of causing hemorrhage or damaging the nerves
  • Temporary alleviation can be achieved by applying a gentle but firm pressure bilaterally on the parotid area or through an indwelling catheter placed in the pharyngeal orifice of the affected pouch. Definitive treatment is surgical
  • 2 surgical treatments performed under general anesthesia are described. 1 consists of the fenestration of the median septum that separates the 2 GPs. The other consists of the resection of a small segment of the medial lamina of the eustachian tube and its associated mucosal fold to create a larger opening of the affected GP into the pharynx. Fenestration of the median septum is used in unilateral GP tympany; both procedures are performed when bilateral involvement
  • Fenestration of the median septum and creation of a fistula between the pharynx and the Eustachian tube with the use of laser equipment or electrosurgery can also be performed

Medications ⬆ ⬇

Outline

MEDICATIONS

Drug(s) of Choice!!navigator!!

  • Preoperative and postoperative medication consists of the administration of systemic antibiotics (procaine penicillin G 20 000 U/kg IV BID or trimethoprim–sulfamethoxazole 30 mg/kg IV BID) and NSAIDs (flunixin meglumine 1 mg/kg IV BID)
  • In cases complicated by aspiration pneumonia or GP empyema, administration of broad-spectrum antibiotics

Contraindications/Possible Interactions!!navigator!!

α2-Agonist agents should be used with caution in horses with GP tympany as they may worsen upper airway obstruction.

Follow-up ⬆ ⬇

FOLLOW-UP

  • In the absence of aspiration pneumonia or GP empyema, the prognosis for a unilateral GP tympany is favorable
  • Recurrence rate following a surgical correction is 30%. The prognosis for a bilateral GP tympany is guarded

Miscellaneous ⬆ ⬇

MISCELLANEOUS

Abbreviations

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

Suggested Reading ⬆ ⬇

Blazyczek I, Hamann H, Deegen E, et al. Retrospective analysis of 50 cases of guttural pouch tympany in foals. Vet Rec 2004;154:261–264.

Blazyczek I, Hamann H, Ohnesorge B, et al. Inheritance of guttural pouch tympany in the Arabian horse. J Hered 2004;95:195–199.

Ragle CA. Guttural pouch disease. In: Robinson NE, ed. Current Therapy in Equine Medicine, 5e. Philadelphia, PA: WB Saunders, 2003:386–390.

Author(s) ⬆

Author: Ludovic P. Bouré

Consulting Editors: Daniel Jean and Mathilde Leclère