EQUINE VETERINARY EDUCATION / AE / FEBRUARY 2018


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Fig 2: Post-mortem images of different strangles infected guttural pouches showing different stages in the development of chondroids. a) Gross empyema, b) soft, semi-formed chondroids and c) firm, formed chondroids.


Fig 3: a) This chronically infected lymph node on the floor of the medial guttural pouch compartment (surrounded by local anaesthetic and pus) never fully drained and was believed to be the cause of the ongoing guttural pouch infection with S equi var equi. b) and c) demonstrate its drainage by laser surgery (image courtesy of R. Reardon).


they rupture into the guttural pouches (Fig 3) or guttural pouch penetration from sharp ingested foreign bodies (Fig 4). Foals with guttural pouch tympany, frequently have concurrent empyema related to poor drainage and anatomical distension of affected pouches. Guttural pouch neoplasia can affect drainage predisposing to infection (Drew et al. 2016). Restricted guttural pouch drainage can also cause


Fig 4: An ingested metallic foreign body (broken hairclip) has penetrated the guttural pouch causing chronic empyema with a large abscess on its floor (arrows).


Other less common reasons for guttural pouch empyema


to become chronic include persistent drainage of the retropharyngeal lymph nodes that usually heal over after


ongoing empyema for different reasons. If extreme distension of a guttural pouch with exudate occurs (Fig 5) this pouch distension can put pressure on the mucosal flap (plica salpingopharyngeus) at the inflamed pharyngeal ostium that occludes drainage. Less commonly, a permanent anatomical stenosis of the ostium can occur with, or without, any history of prior upper airway infection. Ostial stenosis can lead to the accumulation of viscous mucoid (indicating possible developmental origin or acquired stenosis of noninfectious cause) or more commonly purulent exudate (possibly indicating prior guttural pouch infection), usually involving one pouch. Occasionally, such guttural pouches with restricted drainage may spontaneously fistulate into the nasopharynx, but if they contain chondroids larger than the acquired ostium, they cannot drain fully (Fig 5) and the guttural pouch empyema will remain.


© 2016 EVJ Ltd


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