Large Animal Diagnostic Imaging Society

5 year old Saddlebred gelding with recurrent epistaxis

Two prior occasions of mild right sided epistaxis. Recently experienced acute onset, severe, bilateral epistaxis.


5-year old Saddlebred gelding with 2 prior occasions of mild right sided epistaxis. Recently experienced acute onset, severe, bilateral epistaxis. Since then epistaxis has been intermittent and at times severe. No other significant medical history.


CT Images

Caudodorsally in the right guttural pouch, centered in the medial compartment and extending laterally, is a large, lobular soft tissue mass with ill-defined margins and multiple variably sized and well-defined gas foci. The mass is more attenuating centrally than peripherally and is non-contrast enhancing. The rectus capitus muscles are displaced to the left. The nasopharynx and nasal passages, worse ventrally, contain a moderate amount of heterogenous, partially structured non-contrast enhancing soft tissue with similar, multifocal gas. No paranasal bone or conchal destruction is seen. The right maxillary artery, rostral to the branches of the caudal auricular and transverse facial arteries, is focally wide and there is extravasation of positive contrast into the adjacent guttural pouch. Extravasated positive contrast extends into the right ventrolateral aspect of the nasopharynx and nasal passage. The rest of the right maxillary artery and its branches are well defined, normal in diameter with normal luminal opacification.

1. Epistaxis is due to the large right-sided guttural pouch mass which is most likely a fungal plaque in conjunction with hematoma formation secondary to guttural pouch mycosis.

2. Right maxillary artery pseudoaneurysm with active hemorrhage into the guttural pouch, nasopharynx and nasal cavity.

3. Nasopharyngeal and nasal soft tissue is most likely hemorrhage.


Follow up- The patient in this study underwent transarterial embolization of the right maxillary and external carotid arteries. Hemorrhage ceased and the patient was reported to be doing well with no further bleeding at recheck.

Guttural pouch mycosis is a rare and potentially life-threatening disease. Mycotic infections of the guttural pouches are most commonly seen in mature horses, however have been reported in foals (1,6), with no known sex, breed, or geographic predilection. Aspergillosis species are the most common causative fungal organisms.

Anatomically the guttural pouches are paired expansions of the Eustachian tubes located on midline, between the pharynx and skull base. The paired pouches are separated by a combination of a thin midline septum as well as the longus capitis and rectus capitis ventralis muscles. Each pouch is separated into medial and lateral compartments by the stylohyoid bone. The guttural pouches house cranial nerves IX, X, XI, XII, the cranial cervical ganglion, cervical sympathetic trunk, internal carotid artery, as well as the external carotid artery and its caudal auricular, superficial temporal and maxillary artery branches (5). The location of the fungal plaque within guttural pouch will determine which nerves and vessels are affected, and thus will dictate the observed neurologic deficits and which vessels are responsible for hemorrhage. The most common clinical signs are variable degrees of epistaxis, dysphagia due to damage to glossopharyngeal nerve and pharyngeal branches of the vagus nerve (2,5,6), as well as Horner’s syndrome, pharyngeal paralysis and laryngeal hemiplegia (2,5).

Both medical and surgical treatments have been described. Medical therapy alone is generally considered to be less effective than surgery or a combination of the two. The goal of surgery is to prevent hemorrhage. Bleeding is reported most commonly from the internal carotid artery and less commonly the external carotid and maxillary arteries (4). If the internal carotid artery is affected, occlusion of artery at the level of the lesion alone is insufficient to prevent all possible hemorrhage. Blood flow through the non-affected contralateral internal carotid artery into the cerebral arterial circle will maintain pressure in the affected artery, and can allow retrograde blood flow and continued hemorrhage (5). For this reason full surgical treatment involves two site occlusion of the affected artery on the cardiac and peripheral side of the lesion. Techniques include passage of a temporary balloon catheter past the lesion and placement of a permanent ligature at the lesion (2,4,5), as well as transarterial coil embolization via fluoroscopic guidance (4,5). Reported medical therapies consist of topical administration of various antifungal agents (1,2,6), hydrogen peroxide (2), povidone iodine (2), oxygen therapy (4,6) with or without manual debridement of the fungal plaques via endoscopy prior to topical therapy (1,6).


1- Chidlow, H. B., & Slovis, N. M. (2015). Guttural pouch mycosis in two foals. Equine Veterinary Education, 29(4), 213–218.

2- Dobesova, O., Schwarz, B., Velde, K., Jahn, P., Zert, Z., & Bezdekova, B. (2012). Guttural pouch mycosis in horses: A retrospective study of 28 cases. Veterinary Record, 171(22), 561–561.

3- Genton, M., Farfan, M., Tesson, C., Laclaire, A. L., Rossignol, F., & Mespoulhes‐Rivière, C. (2021). Balloon catheter occlusion of the maxillary, internal, and external carotid arteries in standing horses. Veterinary Surgery, 50(3), 546–555.

4- Lepage, O. M., Di Francesco, P., Moulin, N., Gangl, M., Texier, G., Marchi, J., & Cadoré, J.-L. (2021). The effect of topical oxygen therapy in horses affected with mycosis of the guttural pouch: An experimental pilot study and a case series. Animals, 11(11), 3329.

5- Matsuda, Y., Nakanishi, Y., & Mizuno, Y. (1999). Occlusion of the internal carotid artery by means of microcoils for preventing epistaxis caused by guttural pouch mycosis in horses. Journal of Veterinary Medical Science, 61(3), 221–225.

6- Millar H. (2006). Guttural pouch mycosis in a 6-month-old filly. The Canadian veterinary journal = La revue veterinaire canadienne, 47(3), 259–261.

7- Pollock, P. J. (2007). Diagnosis and management of guttural pouch mycosis. Equine Veterinary Education, 19(10), 522–527.×240162

8- Whitehead, A. E., Whitty, J., Scott, M., & Léguillette, R. (2018). Reversible dysphagia secondary to guttural pouch mycosis in a gelding treated medically with voriconazole and surgically with carotid occlusion and esophagostomy. The Canadian veterinary journal = La revue veterinaire canadienne, 59(2), 165–170.