Secondary guttural pouch infection following the

Secondary guttural pouch infection following the alveolarfracture of the
mandible in an 8 Year Old Gelding
IGFP - Kongress
Niedernhausen
7./8. März 2015
Introduction
Guttural pouch mycosis (Aerosacculitis mycotica) is a disease of the upper airway
track.
It is commonly caused by the physiological, facultative pathogenic flora predominantly a fungal causative agent, and most often affects only one of the
bilateral guttural pouches. The locally focused inflammation alters mucous
membranes and the anatomical structures lying underneath. In severe cases it
may lead to erosions in guttural pouch blood vessels such as arteria carotis
interna, arteria carotis externa and arteria maxillaris (rare) with its main symptom
being a non-exercise-induced epistaxis. Therefore, in many cases the necrotising
inflammation of the guttural pouch maintains unnoticed during the clinical
examination until the advanced stadium with arterial erosions occurs. (1)
The differential diagnosis includes bacterial guttural pouch infections with its
predisposing factors, such as irritation of the mucous membranes. Furthermore,
the mechanical irritation of the mucuos membranes through the pulsation of the
arterias, as well as stylohyoids fractures, bulla tympanica or one of the muscles
(m. longus capitis ventralis or m. longus rectus) trauma, should be considered as
causative agents. (1,3,4). The guttural pouch (Diverticulum tubae auditivae) is an
air-filled sac that develops as a ventral diverticulum of the auditory tube (Tuba
auditiva, Eustachian tube). It builds a junction between the middle ear (otis
media) and pharynx and can be found in all equine species. The guttural pouch
contains segments of the cranial nerves VII, IX, X, XI, XII, the chorda tympani and
the cervical cranial ganglion of the sympathetic trunk. The most relevant blood
vessels in the guttural pouch are arteries carotis interna and externa (1,2,4).
The branch named ramus massetericus rises from the arteria carotis externa
and is followed by arteria auricularis caudalis and arteria temporalis superficialis.
The latter gives an origin to the arteria maxillaris which supplies dorsolateral
guttural pouch area with blood. The further extension of arteria maxillaris is
arteria alveolaris inferior, meandring through the canal of mandibule. Arteria
alveolaris inferior supplies blood to molars and premolars. It terminates at
foramen mentale as arteria mentalis. (1,2)
Clinical examination
An 8 year old Welsh Pony gelding was presented at the clinic with the
symptoms of epistaxis and yellow nasal discharge. The horse had no history of
respiratory problems, weight loss, poor performance or food intake disorders.
Clinical examnation revealed enlarged mandibular lymphonodes and unilateral
bloody discharge from the left nostril. The temperature, heart and respiration
rates were within normal limits. Ausculation of the trachea and lungs revealed
clean respiratory sounds.
Endoscopic examination
Both of the guttural pouches were examined with an endoscope through the openings (plica
salpingopharyngea). Passing the endoscope through the left nostril revealed a yellowish discharge
emerging from the opening of the guttural pouch (Pic1). The mucous membranes of the dorsal, lateral and
medial recess with all the following structures were veiled in a thick coat of secretion (Fig 2).
The arteria carotis interna had visible erosions from which the bleeding was emerging (Fig.3).
Fig. 1: Yellowish discharge emerging from the opening of
the guttural pouch
Post mortem examination
The macroscopic examination of the cranium revealed a 3 cm long fracture of the mandibule body, at the level of
306 and 307 (Fig 5). The fracture line originated at 307 rostro-buccal and lined apical through the canal of the
mandibule. Originating at the mandibule body and ending at its ramus, the bone tissue revealed severe changes
(Fig 4). Based on the sclerotic bone proliferations and high-grade pathological findings, a chronic infection and
inflammation were diagnosed.
Bild 4
Bild 2
Bild 3
Fig. 2: Mucous membranes of the dorsal, lateral and medial
recess veiled in a thick coat of secretion
Fig. 3: Erosions of the A.carotis interna
Fig. 4 Sclerotical bone proliferations as a sign of a
chronic infection
Fig. 5: The 3 cm long Mandible fracture
Therapy
The therapy of a guttural pouch mycosis differentiates between medical and surgical treatment possibilities. The
conservative/medical therapy consists of antifungal medications based on antimycogram (the typically used are
miconasole, eniliconasole, clotrimasole) with topical flushing over extensive duration of time. The surgical treatment
consists of ligature of the vessels and integration of an intravascular balloon or coil to allow obliteration of arterial flow
proximal and distal to the fungal lesion (1,3,5). The thorough description of surgical treatment is described by Auer & Stick
(6).
Given the prognosis, the owner has decided to have the horse euthanised.
Discussion
The presented post-mortem examination indicates a possibility of ascending infection along the mandibular canal through
the maxillary artery that supplies blood to the lateral area of the guttural pouch. In the literature, no comparable case has
currently been described. Only seldom lead mycotic pathogens from the surroundings of the horse to the guttural pouch
mycosis. It is a rare condition, triggered by the predispoing factors. In this case, the traumatic alveolar fracture with
subsequent ascending infection is suspected to be the cause of the guttural pouch mycosis.
Fig. 6: Ventral view of Corpus mandibularis
Literature
Correspondence
1) Untersuchungen zur Therapie der Luftsackmykose des Pferdes – Ligatur der Arteria carotis interna mittels
transendoskopischer Clipapplikation, Dissertation von Robert Georg Markus, Hannover 2002
2) Atlas der Anatomie des Pferdes: herausgeben von Christoph Mülling, Christiane Pfarrer, Sven Reese, Sabine Kölle,
Klaus-Dieter Budras, 2008
3) ) Trans-arterial coil embolization of the internal carotid artery in standing horses. ; Benredouane K, Lepage O. ;Vet
Surg. 2012 Apr;41(3):404-9.
4) Equine Internal Medicine; Stephen M. Reed, Warwick M. Bailay, second edition, 2004, Elsevier (USA)
5) Treatment of guttural pouch mycosis. Church S, Wyn-Jones G, Parks AH, Ritchie HE. Equine Vet J. 1986 Sep;
18(5):362-5.
6) Auer and Stick, Equine Surgery Fourth Edition, 2012, section VI, chapter 46, 623-643
Souel Maleh IGFP/c PDPP
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