Progression of mycosis of the auditory tube diverticulum (guttural pouch) after arterial occlusion in a horse with contralateral temporohyoid osteoarthropathy

CASE DESCRIPTION: A 6-year-old Appaloosa mare was examined because of inappetance, difficulty eating, and swelling and mucopurulent discharge in the right eye. CLINICAL FINDINGS: Results of a CBC and serum bio-chemical analysis revealed no important findings. Ophthalmologic examination revealed scarring and ulceration of the superficial layers of the cornea. Endoscopic examination of the upper portion of the respiratory tract and auditory tube diverticula (guttural pouches) revealed abnormal thickness of the right stylohyoid bone and a plaque suggestive of mycotic growth on the left internal carotid artery. Radiographic examination revealed right-sided otitis media. Temporohyoid osteoarthropathy in the right guttural pouch and mycosis in the left guttural pouch were diagnosed. TREATMENT AND OUTCOME: Ceratohyoidectomy of the right stylohyoid bone was performed, and the left internal carotid artery was occluded via placement of stainless steel spring embolization coils. The mare regained the ability to eat without difficulty and improved clinically for approximately 4 weeks. However, the mare returned to the medical center 53 days after surgery with left-sided Horner syndrome, atrophy of the right side of the tongue, and a 3-week history of dysphagia and weight loss. Endoscopic evaluation revealed progression of mycotic growth in the left guttural pouch. The mare was euthanatized. CLINICAL RELEVANCE: Although the mycotic lesion in the left guttural pouch was an incidental finding at the time of initial examination, the lesion progressed to cause dysphagia and Horner syndrome after occlusion of the left internal carotid artery, a treatment that is typically associated with resolution of guttural pouch mycosis. Arterial occlusion is not necessarily a reliable method of resolving guttural pouch mycosis.     

Guttural pouch hemorrhage associated with lesions of the maxillary artery in two horses

A two year old Thoroughbred gelding, presented with guttural pouch hemorrhage, had the internal and external carotid arteries ligated. Guttural pouch mycosis was detected on endoscopic examination. After one month of topical antifungal therapy, the horse was returned and euthanized because of recurrent epistaxis. A bacterial infection of the guttural pouch with associated ulceration and hemorrhage from the maxillary artery was found at necropsy.

A two year old grade gelding had ulceration and hemorrhage from the external carotid artery. Utilizing balloon-tipped catheters and arterial ligation, hemestasis was achieved in the internal carotid artery and the external carotid artery and its branches. Mycotic ulceration of the internal carotid artery was detected endoscopically and treated with local antifungal therapy for one month. Thirty-three days postoperatively the horse returned, bleeding from a lesion in the maxillary artery. The rationale for surgical intervention to prevent epistaxis associated with guttural pouch mycosis and possible etiologies for postsurgical epistaxis are discussed.

     

Guttural pouch empyema secondary to a periocular foreign body

This report describes a 3‐year‐old gelding presenting with signs of injury to its left eye following an accident in which the horse crashed into a hedge. The first treatment attempted to treat infections in the eye and respiratory tract due to secretions identified in the trachea. The horse did not improve and further clinical and radiographic evaluations detected a guttural pouch empyema. Surgical drainage was performed and antimicrobial treatment continued. However, the horse presented with severe epistaxis and euthanasia was elected due to suspected arterial rupture. At necropsy, a round and stiff branch plant was found creating a fistula from the left orbit to the left guttural pouch. Another branch was found inside the pouch, confirming the origin of the persistent infection and severity of the tissue lesion.     

CT examination of the guttural pouch (auditory tube diverticulum) in Przewalski's Horse (Equus przewalskii).

The domestic horse (Equus caballus) have the large symmetrical guttural pouches (the auditory tube diverticulum) formed by saccate bulge of the auditory tube. In this study, CT examination was carried out in the head of Przewalski's horse (Equus przewalskii), the only true wild horse living at present. As results of the examination, Przewalski's horse possessed the large symmetrical guttural pouches divided into medial and lateral compartments by the stylohyoid bone. Moreover, the right and left guttural pouches meet each other at the median part to form a thin septum. As CT sections get close to the part of the occipital condyle, the lateral compartment disappeared, and the medial compartment gradually became small toward the base of the skull. These results indicate that the nuchal-basal part of the medial compartment is not well-developed as compared with the domestic horse.     

Primary distension of the guttural pouch lateral compartment secondary to empyema

A 6-year-old, 420-kg quarter horse gelding was presented with a 2-month history of difficulty swallowing and dyspnea. The horse was diagnosed with a right guttural pouch empyema with many large chondroids. Two surgeries were required to completely remove all the chondroids from what proved to be a primary distension of the guttural pouch lateral compartment.     

Guttural pouch leiomyosarcoma causing nasopharyngeal compression in a pony

A 14‐year‐old Connemara cross gelding presented with abnormal respiratory noise and exercise intolerance. Upper airway endoscopy, ultrasonography, radiography and computed tomography revealed a large mass within the left guttural pouch causing marked left dorsal nasopharyngeal collapse and displacement and compression of the right guttural pouch. The horse was subjected to euthanasia and a post‐mortem examination confirmed the above findings. Histological and immunohistochemical examinations of the mass confirmed a diagnosis of guttural pouch leiomyosarcoma, a lesion previously unreported at this site.     

Temporohyoid osteoarthropathy and unilateral facial nerve paralysis in a horse

A 13-year-old broodmare was referred for weight loss and left facial nerve paralysis. Bilateral temporohyoid osteoarthropathy was diagnosed based on proliferation of the temporohyoid joints and stylohyoid bones on radiographs and guttural pouch endoscopy. The left side was more severely affected. Treatment resulted in little or no improvement.     

Diverticulum and fistula of the lower cervical esophagus in a horse

Esophageal diverticulum and perforation were diagnosed in a horse. The condition was characterized clinically by dysphagia, polypnea, diffuse swelling of the ventral aspect of neck and cutaneous fistula. Endoscopic examination revealed the presence of food material in the guttural pouch. A barium sulfate esophagram was performed to outline the diverticulum.

Exploratory surgery confirmed esophageal perforation and entrapment of food material between the muscular planes of the cervical region and the horse was euthanized. At necropsy a food-filled periesophageal tract was found extending from the esophageal rupture to the left guttural pouch.

     

Occlusion of the internal carotid artery by means of microcoils for preventing epistaxis caused by guttural pouch mycosis in horses.

Occlusion of the internal carotid artery by insertion of intravascular platinum microcoils for guttural pouch mycosis was experimentally evaluated in 9 healthy adult Thoroughbred horses. The internal carotid artery was ligated to its origin, and an arteriotomy was made distal to the ligature, which was then occluded by insertion of the microcoil approximately 13 cm distal to its origin. Cessation of blood flow was determined visually and by angiography at the arteriotomy site. Six horses were evaluated for complication clinically and by endoscopy after surgery. One horse was necropsied after 30 days of surgery for histological evaluation of artery thrombus formation. In the other 3 horses, the blood flow of the right internal carotid artery was monitored, before and after microcoil occlusion of the left internal carotid artery. One or 2 microcoils stopped blood flow within a few minutes. No other abnormal findings were observed clinically. Thrombus was observed in the occluded segment of 1 horse 30 days after insertion; but no abnormalities were detected. The blood flow in the right internal carotid artery increased by approximately 28-58% after occlusion of the left internal carotid artery. This microcoil vascular occlusion technique causes an effective thrombosis, and based on experimental studies and clinical application in 2 horses with epistaxis due to guttural pouch mycosis, this technique would appear to be safe and efficacious.     

Detachable latex balloon occlusion of an internal carotid artery with an aberrant branch in a horse with guttural pouch (auditory tube diverticulum) mycosis

An aberrant branch of the internal carotid artery was detected by angiography in a horse with guttural pouch (auditory tube diverticulum) mycosis after the distal portion of the artery had been occluded by use of a detachable latex balloon. A second balloon was placed to eliminate retrograde hemorrhage from the aberrant branch. The horse recovered and returned to its previous activity. Vascular anomalies of the internal carotid artery my be more common than expected, and have resulted in fatal complications during and after surgical treatment in guttural pouch mycosis. Intraoperative identification of vascular anomalies by use of angiography may avoid these fatal complications.     

Suspected retropharyngeal haemorrhage as a complication of guttural pouch mycosis

An 11-year-old Thoroughbred mare presented for evaluation of severe, acute bilateral epistaxis of several hours’ duration. Endoscopic evaluation revealed active haemorrhage from the right guttural pouch and significant dorsal compression of the nasopharynx. Rapid and severe retropharyngeal swelling developed, prompting placement of a temporary tracheostomy. Guttural pouch mycosis was suspected and transarterial coil embolisation of the right internal carotid, external carotid and maxillary arteries was successfully performed. It was suspected that haemorrhage from the vasculature of the guttural pouch tracked caudally into the retropharyngeal region resulting in significant swelling, pharyngeal collapse and a severely compromised airway. Clinicians should be aware of this rare complication of guttural pouch epistaxis.     

Fistula between the guttural pouches and the dorsal pharyngeal recess as a sequela to guttural pouch mycosis in the horse

An unusual case of a two year old gelding with severe unilateral epistaxis due to guttural pouch mycosis is reported. The lesion had spread to involve the dorso-medial aspects of the right guttural pouch and had formed a fistula between the dorsal pharyngeal recess and both the left and right guttural pouches. The diagnosis, surgical treatment and postoperative management are described.     

Guttural pouch mycosis in a 6-month-old filly

A 6-month-old filly was presented with unilateral epistaxis. Based on clinical signs, endoscopic examination, and postmortem examination, guttural pouch mycosis was diagnosed. The young age of the filly and the fact that this was the 2nd diagnosis of guttural pouch mycosis on this farm was unusual.     

Complications of Balloon Catheterization Associated With Aberrant Cerebral Arterial Anatomy in a Horse With Guttural Pouch Mycosis

A 3-year-old Quarter Horse gelding was treated for left guttural pouch mycosis by ligation and balloon catheterization of the left internal carotid artery. Catheter advancement was shorter (10 cm) than the normally reported distance (13–15 cm), but was observed endoscopically during placement as it coursed within the internal carotid artery through the guttural pouch. The horse developed a persistently abnormal respiratory pattern after catheter placement, failed to gain consciousness, developed pulmonary edema, and died 5.5 hours postoperatively. Postmortem examination revelaed an aberrant left internal carotid arterial course with location of the embolectomy catheter at the junction of the basilar and caudal cerebellar arteries. Brainstem neuronal necrosis and alveolar and interstitial pulmonary edema were identified on histological examination. Angiography may be used to identify aberrant branching patterns. Failure to identify and occlude aberrant branches may result in fatal epistaxis and Brainstem lesions.     

Carotid and cerebral angiography in the horse

Carotid and cerebral angiography has been found to be a relatively simple technique to carry out in the horse. At most it involves a cutdown approach to the carotid artery, followed by catheterisation of the artery and selective catheterisation, if necessary, of one of its three branches. The technique can be carried out with standard equipment normally available within equine hospital facilities. The authors have employed angiography as a routine aid to diagnosis over the past nine years, without encountering any serious complications or adverse reactions. Carotid angiography has been especially valuable in the investigation of horses with guttural pouch mycosis. The technique has permitted the presence of aneurysms to be detected in many cases and significant vascular abnormalities in four cases. This information is valuable for the surgical treatment of horses with guttural pouch mycosis by ligation of the appropriate artery. Other indications for the use of carotid angiography include the investigation of ethmoidal haematoma, idiopathic Horner's syndrome, neoplasia of the head, venous aneurysms and arterial aneurysms in sites not associated with the guttural pouch. There are fewer occasions for the use of cerebral angiography in the horse, but it is indicated as an aid to the differential diagnosis of some abnormalities of the central nervous system.     

The mystery of fungal infection in the guttural pouches

Advances in the understanding of guttural pouch physiology and novel therapeutic approaches to mycotic infections in the horse are reviewed. It is suggested that the guttural pouches may contribute to the regulation of arterial blood temperature, cooling the circulation to the brain to below body temperature. Aspergillus spp. is the major organism found in a guttural pouch affected with mycosis but it is unclear why this agent becomes aggressive. Conventional therapy aims to prevent fatal haemorrhage and to treat any neurological lesions but it is desirable to try to prevent the disease. A technique consisting of inserting a transarterial coil into the internal carotid, external carotid and maxillary arteries in normal and affected horses has been reported to be rapid, safe and effective in occluding the arteries and in inducing regression of the mycotic lesions without adjunctive medical treatment. When faced with acute and uncontrollable epistaxis in the field, the most effective means to reduce haemorrhage is probably the occlusion of both common carotid arteries. However, how such arterial occlusions can result in the successful management of guttural pouch mycosis without antifungal medication remains a mystery.     

Cystic structures in the guttural pouch (auditory tube diverticulum) of two horses.

Two horses were examined for compression of the pharynx from the dorsal pharyngeal wall. Neither horse had a patent opening of 1 of the guttural pouches. Radiography of the guttural pouch region revealed a retropharyngeal opacity that occluded 1 guttural pouch. Organisms were not isolated on bacteriologic culture of fluid obtained from the affected guttural pouch. Surgical exploration of the guttural pouch revealed the lining to be easily removeable by blunt dissection in 1 horse; however, the lining was more firmly attached and removal was not attempted in the second horse. A fenestration between the normal and affected guttural pouch was created in both horses to allow for drainage. The etiopathogenesis of the cyst in the guttural pouches is unknown.     

A case of guttural pouch mycosis in a horse

A case of guttural pouch mycosis in an 11-year-old horse is described. The fungus isolated was identified as Emericella nidulans. Housing under bad hygienic conditions without ventilation for three years might have been a predisposing factor.     

Immune-mediated hemolytic anemia associated with trimethoprim-sulphamethoxazole administration in a horse.

A 10-year-old, thoroughbred gelding was administered sulphonamide drugs during surgical treatment of guttural pouch mycosis. The horse became anemic and a diagnosis of immune-mediated hemolytic anemia was made after other causes of anemia had been ruled out. The anemia resolved after the drugs were withdrawn.     

Gutteral pouch mycosis and mycotic encephalitis in a horse

A case of mycotic encephalitis in a horse with guttural pouch mycosis is described. A liquid pellet feed binder contaminated with Aspergillus sp. and erroneously mixed in a feed concentrate was a possible source of infection.