Guttural Pouch Mycosis
Learn what the condition is, how it may be detected early, how it is treated or managed, and which breeds or species are linked to it.
Condition snapshot
A concise guide to the condition’s pattern, detection, management and urgency.
Emergency presentation is possibleNosebleed, dysphagia or neurological signs can precede fatal haemorrhage and require emergency veterinary care.
This snapshot is a general guide, not a diagnosis or treatment plan. New, severe or worsening signs require veterinary assessment.
About the condition
Guttural pouch mycosis is a life-threatening fungal infection, usually involving an Aspergillus species growing as a plaque on the lining of one guttural pouch. The critical danger is anatomical: major arteries and several cranial nerves course across the pouch wall. Fungal invasion can erode an artery or damage nerves controlling swallowing, the larynx, eye and face.
Spontaneous bleeding from one or both nostrils is the most common warning. An initial episode may stop on its own and be mistaken for minor trauma, yet a later haemorrhage can be rapidly fatal. Dysphagia, coughing while eating, feed or water at the nostrils, abnormal respiratory noise, facial weakness, drooping eyelid or a low head carriage indicate nerve involvement. Some horses show only discharge or subtle upper-airway dysfunction before a crisis.
The condition is not contagious between horses and is not the same as guttural pouch empyema. Identifying fungus in a non-invasive sample is insufficient without a compatible plaque or tissue invasion, because environmental fungi are common. Conversely, an unexplained nosebleed in an adult horse must be treated seriously even when it has ended.
Prognosis depends on controlling the threatened artery before another bleed and on the degree of cranial-nerve injury. Vascular occlusion can prevent catastrophic haemorrhage, but swallowing dysfunction may persist because nerves recover slowly or incompletely. Aspiration pneumonia is a major secondary risk. Manipulation, tubing or lavage before the vascular anatomy is assessed can dislodge a clot, so suspected cases require careful referral-level planning rather than routine flushing of the pouch.
Fungal plaques usually form over major arteries and cranial nerves within the pouch. A small sentinel nosebleed can precede fatal arterial rupture, while nerve damage produces dysphagia, laryngeal paralysis or Horner syndrome. Because bleeding may stop temporarily, an apparently recovered horse after spontaneous epistaxis remains an emergency until both pouches and vascular risk are assessed.
Screening & Early Detection
An unexplained spontaneous nosebleed warrants urgent veterinary examination, confinement and minimal stress. The horse should not be exercised or transported casually after bleeding stops. Endoscopy is used to inspect both guttural pouches, but it is performed cautiously because disturbing a plaque or clot can trigger severe haemorrhage. Plaque position relative to the internal or external carotid and maxillary arteries guides treatment.
Blood count and packed cell volume assess blood loss; cross-matching and access to transfusion may be needed. CT angiography or other vascular imaging can define the involved vessel and collateral circulation for surgical planning. Neurological examination evaluates swallowing, laryngeal function, pupil and facial movement. Feed material in the trachea or abnormal lung findings prompts assessment for aspiration pneumonia.
Differentials for epistaxis include exercise-induced pulmonary haemorrhage, ethmoid haematoma, nasal trauma and pulmonary disease. Blood seen after strenuous exercise does not automatically prove EIPH, particularly when bleeding is profuse or occurs at rest. Cytology, culture or histology can support fungal identification, but the endoscopic lesion and its vascular relationship are the urgent diagnostic priorities.
Treatment & Management
Preventing fatal haemorrhage is the first treatment priority. The artery associated with the fungal plaque is occluded on both sides of the lesion where possible, commonly using transarterial coils, plugs or balloons, or by surgical ligation. Referral should occur before repeated bleeding, because a horse may not survive the next episode. Blood transfusion and emergency stabilisation may be required after major loss.
Topical antifungal medication can be applied to the plaque, and systemic antifungal treatment is used in selected cases, but medication alone cannot reliably protect an eroded major artery. Surgical or endoscopic debridement is undertaken only with vascular risk controlled. The horse is monitored for recurrent bleeding and complications of arterial occlusion.
Dysphagia needs intensive management to prevent aspiration. Oral feed and water may be withheld when swallowing is unsafe; temporary alternative feeding, tracheal suction, antibiotics for documented aspiration pneumonia and supportive care may be necessary. A permanent tracheostomy or other airway procedure is occasionally required for laryngeal dysfunction. Serial endoscopy documents plaque regression, while swallowing and cranial-nerve function are reassessed independently. Survival is substantially improved when the artery is secured early, but persistent dysphagia carries a guarded prognosis even after the fungus is controlled.
Breeds or species affected
Akhal-Teke
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Anglo-Arabian
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Arabian
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Barb
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Caspian
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Kathiawari
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Marwari
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Shagya Arabian
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Thoroughbred
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American Quarter Horse
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American Paint Horse
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Appaloosa
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Australian Stock Horse
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Brumby
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Waler
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Morgan
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Standardbred
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American Saddlebred
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Tennessee Walking Horse
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Missouri Fox Trotter
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Rocky Mountain Horse
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Peruvian Paso
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Criollo
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Mustang
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Canadian Horse
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Andalusian
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Lusitano
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Lipizzaner
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Friesian
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Dutch Warmblood
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Hanoverian
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Holsteiner
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Oldenburg
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Westphalian
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Trakehner
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Selle Français
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Belgian Warmblood
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Danish Warmblood
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Swedish Warmblood
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Swiss Warmblood
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Australian Warmblood
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Irish Sport Horse
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Cleveland Bay
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Württemberger
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Zangersheide
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Knabstrupper
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Orlov Trotter
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Camargue
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Icelandic Horse
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Pony of the Americas
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Quarter Pony
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Miniature Horse
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Clydesdale
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Shire
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Percheron
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Belgian Draft
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Suffolk Punch
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American Cream Draft
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Ardennes
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Breton
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Boulonnais
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Comtois
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Dutch Draft
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North Swedish Horse
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Norwegian Fjord
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Haflinger
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Gypsy Cob
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Irish Draught
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Welsh Pony and Cob
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Connemara Pony
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New Forest Pony
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Dartmoor Pony
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Exmoor Pony
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Shetland Pony
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Highland Pony
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Fell Pony
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Dales Pony
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Australian Pony
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Finnhorse
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Black Forest Horse
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