Update on disorders and treatment of the guttural pouch.

The most common disorders of the equine guttural pouches are empyema, tympany, mycosis, and temporohyoid osteoarthropathy. Diagnosis of these conditions is made primarily by imaging with endoscopy, radiographs, computed tomography, and/or MRI. Medical treatment with anti-inflammatories, antimicrobials, and/or antifungals may be successful in some cases, but many of these disorders necessitate surgical intervention. Direct surgical approaches to the guttural pouch are difficult because of their complex anatomy and relationship with important structures, thus precipitating a move toward minimally invasive procedures when possible.

Outcome of treatment in 35 cases of guttural pouch mycosis.

This paper describes the outcome of treatment of 30 cases of guttural pouch mycosis by ligation of the internal carotid artery on the cardiac side of the lesion and lavage of the affected pouch with natamycin. Twenty-three horses recovered fully following this treatment while laryngeal hemiplegia persisted in one case and slight dysphagia caused by pharyngeal hemiplegia in another. The remaining five horses died or were destroyed. Five horses with guttural pouch mycosis, which had shown no epistaxis but had pharyngeal hemiplegia, were treated by topical natamycin alone. Only two of these survived, of which one remained slightly dysphagic. Ligation of the internal carotid artery of the cardiac side of the lesion is an effective means of reducing the chance of fatal epistaxis in cases of guttural pouch mycosis. Some cases of pharyngeal hemiplegia can make a complete recovery although it may take 12 to 18 months.

Guttural pouch mycosis in six horses in New Zealand.

CASE HISTORIES: Six horses from several geographical locations in New Zealand presented with signs of guttural pouch mycosis. All horses had experienced epistaxis within 14 days of presentation. CLINICAL FINDINGS AND TREATMENT: In five horses with epistaxis, a diagnosis of guttural pouch mycosis was made on endoscopic observation of fungal plaques in the affected guttural pouches. One of these cases died before surgery was attempted. The remaining four cases underwent ligation and balloon catheter occlusion of the internal carotid artery of the affected pouch. Three of these horses survived and were reported to be healthy 1 year after surgery. One case died from haemorrhage 8 weeks after surgery. In a sixth horse, endoscopy was carried out but the affected guttural pouch which had recently haemorrhaged was not entered. This horse underwent ligation of the internal carotid and occipital arteries of the affected side but subsequently died. A diagnosis of guttural pouch mycosis of the maxillary artery was confirmed by post-mortem examination. Histology revealed fungal hyphae within thrombi in the lumen of the maxillary artery in the affected guttural pouch. Two horses displayed signs consistent with cranial nerve damage in the guttural pouch. DIAGNOSIS: Guttural pouch mycosis. CLINICAL RELEVANCE: This is the first report of which we are aware of the diagnosis and treatment of clinical cases of guttural pouch mycosis in horses in New Zealand. Practitioners in New Zealand should be aware of the presence and manifestations of this disease and be prepared to treat or refer horses for surgical treatment before fatal haemorrhage and/or profound neurologic signs occur.

Guttural pouch mycosis in horses: a retrospective study of 28 cases.

The medical records of 28 horses with guttural pouch mycosis were reviewed. The most commonly observed clinical signs were nasal discharge, epistaxis, dysphagia and/or cough. All 28 horses had the disease unilaterally, however, in five of them, it had spread into the contralateral pouch via the mesial septum. Three horses were treated medically, 11 horses underwent surgery and seven horses were treated both medically and surgically. Fifty percent of horses (14/28) were euthanased or died, fifty percent of horses (14/28) survived. There was no significant correlation between treatment method (medical, surgical, combination) and survival rate. The most common reason for euthanasia was dysphagia due to pharyngeal dysfunction. There was a highly significant correlation between the presence of dysphagia and non-survival (p=0.008).