Differential diagnosis: ethmoid hematoma, guttural pouch mycosis, primary sinusitis, paranasal sinus cyst, tooth root abscess with secondary sinusitis.
On endoscopy the following images could be obtained:
Image 1: View of the larynx with mild yellow colored discharge coming from the left guttural pouch opening. The larynx shows normal function.
Image 2: A close-up of the left guttural pouch opening and noted discharge.
Image 3: A close-up of his middle nasal concha and ethmoid conchae.
Image 4: Inside view of the left guttural pouch with fungal plaque overlaying the internal carotid artery.
Diagnosis: Left guttural pouch mycosis with involvement of the left internal carotid artery. Surgical treatment was initiated by retrograde balloon occlusion and normograde ligation of the internal carotid artery.
Guttural pouch mycosis: The cause of guttural pouch mycosis is unknown to date, but if a biopsy is taken most commonly seen are Aspergillus spp. In general no age, sex or regional predisposition has been reported. The disease is relatively rare and most of the time affects only one guttural pouch.
Clinical signs are moderate or severe bleeding from the nose. In most cases, several occasions of bleeding precede a fatal episode. For a few days after a bleeding event, mucous and dark bloody trickles dripping from the nostril might be noted. On upper airway endoscopy, bloody or serosanguinous discharge can be noted dripping from the guttural pouch opening of the affected side after an acute bleeding episode or yellow discharge if the bleeding episode had happened long ago. When entering the guttural pouch a diphtheritic plaque can be seen at the roof of the guttural pouch covering the internal carotid artery in the medial compartment and/or the external carotid artery or its branches within the lateral compartment of the guttural pouch. In the incident of acute bleeding or in the days after a bleeding event, the guttural pouch might be filled with blood clots and identification of the mycotic plaque can be impossible.
Treatment options include medical treatment with daily lavage with antifungal medications or iodine solution, but severe or even fatal bleeding episodes can occur while waiting for the fungal plaque to dissolve. Therefore, surgical intervention is indicated, which entails occlusion of the affected artery by either a balloon catheter or intravascular coils. Because of the circle of Willis, it is important to occlude the lumen of affected vessels on either side of the mycotic plaque, which will be achieved by the balloon catheter or vascular coil. Advantages of the intravascular coils are that they do not need to be removed after surgery, but extra equipment like fluoroscopy is necessary to perform this procedure. The approach for intravascular coils is made via a small incision over the common carotid artery in the mid-cervical region. To place balloon catheters the approach is more challenging via hyovertebrotomy for occlusion of the internal carotid artery, but supplies are less expensive. The balloon catheter will be removed during a standing outpatient procedure and sedation about three to four weeks after placement.
Aftercare consists of stall rest and re-evaluation of the size of the mycotic plaque within the guttural pouch. Most plaques have resolved after eight weeks. Complications caused by the fungal infestation within the guttural pouch are fatal bleeding (about 50% of affected horses die without surgical intervention), dysphagia, soft palate displacement, and laryngeal paralysis. In some cases, these neurologic symptoms can subside following treatment of the guttural pouch mycosis via surgical occlusion of the affected vessels. In some cases, additional surgery to treat laryngeal paralysis or soft palate displacement might be necessary. In very rare cases bleeding can reoccur if aberrant vessels prevent full occlusion of the affected artery. Prognosis is generally good after surgical occlusion (87%). Only 52% of medically treated horses survive.
1. Freeman DE, Hardy J. Guttural pouch. In: Auer JA, Stick JA, editors. Equine surgery. 4th edition. St.Louis, Missouri: Elsevier Saunders Co.; 2012 p. 623–642. 2. Cook, W.R., Campbell, R.S.F., Path, M.C., and Dawson, C. (1968) The pathology and aetiology of guttural pouch mycosis in the horse. Vet. Rec. 83, 422-428. 3. Freeman DE, Donawick WJ.Occlusion of internal carotid artery in the horse by means of a balloon-tipped catheter: clinical use of a method to prevent epistaxis caused by guttural pouch mycosis. J Am Vet Med Assoc. 1980 Feb 1;176(3):236-40. 4. Lepage OM, Piccot-Crezollet C. Transarterial coil embolization in 31 horses (1999–2002) with guttural pouch mycosis: a 2-year follow-up. Equine Vet J 2005; 37:430–434. 5. Freeman DE. Complications of Surgery for Diseases of the Guttural Pouch. Vet Clin Equine 24 (2009) 485–497.