Empyema of the guttural pouch (auditory tube diverticulum) in horses: 91 cases (1977-1997)

OBJECTIVE: To identify features of guttural pouch (auditory tube diverticulum) empyema in horses and compare findings of uncomplicated guttural pouch empyema with guttural pouch empyema complicated by chondroids. DESIGN: Retrospective study. ANIMALS: 91 horses with guttural pouch empyema. PROCEDURE: Medical records of horses with guttural pouch empyema were reviewed. RESULTS: The most common owner complaint and abnormal finding was persistent nasal discharge. Chondroids were detected in 21% (19/91) of affected horses. Streptococcus equi was isolated from the guttural pouch in 14 of 44 horses; for Streptococcus spp, in vitro resistance to sulfadimethoxine and trimethoprim-sulfamethoxazole was detected. Retropharyngeal swelling and pharyngeal narrowing were significantly more prevalent in horses with chondroids, compared with horses with uncomplicated empyema. Ninety-three percent of affected horses were discharged from the hospital; at time of discharge, 66% had complete resolution of disease, 19% had improvement without resolution, and 15% did not have improvement. CONCLUSIONS AND CLINICAL RELEVANCE: Horses with persistent nasal discharge should be examined endoscopically for guttural pouch empyema. Treatment with lavage offers a good prognosis for resolution of uncomplicated guttural pouch empyema. Aggressive treatment with lavage and endoscopic snare removal of chondroids offers a good prognosis and may make surgical intervention unnecessary.     

Endoscopic and bacteriological findings in a chronic outbreak of strangles

Recently there has been increased awareness of the role of the carrier state in propagating Streptococcus equi var equi (S equi) infections (strangles), although the anatomical location of the organisms in chronic carriers has not been consistently established. This case report describes a chronic strangles outbreak in a riding school, that was monitored over six months by repeated clinical and endoscopic guttural pouch examinations. All asymptomatic horses that had positive S equi cultures on nasal swabs or guttural pouch lavages were found to have lesions in their guttural pouches. These lesions included empyema, chondroids and previously undescribed chronic discharging lesions on the floor of the medical compartment of the guttural pouches. These observations further support previous studies indicating the importance of investigating the guttural pouches in horses suspected to be asymptomatic carriers of this organism.     

Standing surgical removal of inspissated guttural pouch exudate (chondroids) in ten horses

OBJECTIVE: To report use of a modified Whitehouse approach in standing horses for management of inspissated guttural pouch empyema. STUDY DESIGN: Retrospective study. ANIMALS: Adult horses (n=10) with guttural pouch empyema. METHODS: Inspissated exudate in 1 or both guttural pouches was removed surgically through a modified Whitehouse approach, with the horses standing and sedated. Medical records of affected horses were reviewed to determine history; physical, endoscopic, and radiological examination findings; surgical technique; complications, and outcome. RESULTS: All horses had purulent nasal discharge; 3 horses had dysphagia, 2 had recurrent laryngeal neuropathy on the side affected by guttural pouch empyema, and 1 had persistent soft palate displacement. Inspissated exudate was removed safely without causing apparent discomfort. Eight horses returned to their previous level of athletic activity after surgery; 1 horse dysphagic before surgery, was euthanatized because of persistent dysphagia after surgery, and 1 horse died 1 week after surgery for unknown reasons. Streptococcus equi subsp equi was isolated from the affected guttural pouch of 3 horses. CONCLUSIONS: Inspissated exudate can be removed surgically from the guttural pouch in standing horses through a modified Whitehouse approach. CLINICAL RELEVANCE: To eliminate risks associated with general anesthesia and avoid surgical suite contamination, removal of chondroids can be performed in standing sedated horses through a modified Whitehouse approach.     

Laser fenestration of the mesial septum for treatment of guttural pouch chondroids in a pony

OBJECTIVE: To describe removal of guttural pouch chondroids through a laser fenestrated mesial septum in a pony with an obstructed pharyngeal ostium of the left guttural pouch. STUDY DESIGN: Case report. ANIMALS: Pony. METHODS: Transendoscopic laser neodymium:yttrium aluminum garnet (Nd:YAG) fenestration of the mesial guttural pouch septum was made by contact method (bare fiber, 15-25 W, exposure time 4 seconds). Dissected tissue was removed by transendoscopic monopolar electrosurgery (loop electrode, cutting blade) and multiple chondroids of varying size were removed from the left guttural pouch through the fenestration. RESULTS: After removing all chondroids and repeated flushing of the left guttural pouch via the right side, inflammation of the guttural pouch membranes decreased remarkably. The pony was discharged with instructions for transendoscopic lavage once weekly and was reevaluated at 2 months. A permanent septal fenestration was observed and the pony was free of abnormal clinical signs and being used for carriage driving competitions. CONCLUSION: Nd:YAG laser fenestration of the mesial septum is an approach for access to guttural pouch chondroids. CLINICAL RELEVANCE: When guttural pouch empyema and/or chondroids is associated with adhesion of the pharyngeal ostium, laser fenestration of the mesial septum from the opposite guttural pouch should be considered as an alternative approach for access, rather than classic external surgical approaches.     

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.     

Elimination of guttural pouch infection and inflammation in asymptomatic carriers of Streptococcus equi

Three protracted outbreaks of strangles were investigated using endoscopic examination and a total of 14 asymptomatic carriers of Streptococcus equi were identified of which 13 showed evidence of carriage in the guttural pouch. Treatment was initiated to eliminate S. equi colonisation since these animals posed an infectious risk to susceptible horses. Two further horses were referred to us with severe guttural pouch pathology and from which S. equi was cultured, and treatment of these cases is also described. Treatment in the first instance was directed towards removal of gross guttural pouch pathology as seen on endoscopic examination. This was done with a combination of irrigation of the pouch with moderate to large amounts of saline, suction of fluid material and endoscopic manipulation of chondroids. Subsequently, antibiotic treatment was used to eliminate S. equi infection. All animals received systemic antibiotics, in some cases combined with topical antimicrobial treatment. Treatment was generally regarded as successful when the guttural pouches appeared normal and S. equi was not detected in nasopharangeal swabs and pouch lavages on 3 consecutive occasions. Successful treatment of one carrier required surgical intervention due to occlusion of both guttural pouch pharyngeal openings. Fourteen of 15 carriers were successfully treated by endoscopic removal of inflammatory material and antibiotic treatment, without surgical intervention. Five carriers originally given potentiated sulphonamide (33%) required further therapy with penicillin or ceftiofur, administered both systemically and topically, before S. equi infection and associated inflammation of the guttural pouches were eliminated.     

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.     

Cytological and microbiological findings in guttural pouch lavages of clinically normal horses with head restraint

OBJECTIVE: To evaluate the cytological and microbiological contents of guttural pouch washes of ten randomly selected horses restrained so as to prevent them lowering their heads, and to assess the possible effects on the guttural pouch environment in these horses. PROCEDURE: Cytological and microbiological studies were performed on guttural pouch washes of ten clinically normal horses restrained in a standing position so as to prevent them from lowering their heads below normal, as would happen during transportation on long journeys. They were restrained for 12 or 24 h and cytological, bacteriological and mycological findings in guttural pouch washes were recorded. RESULTS: The cytological gradings and neutrophil concentrations of guttural pouch washings were higher in horses that had their heads restrained for a longer period. Washings from these horses were more likely to contain cultivable bacteria and were the only washes yielding potentially pathogenic bacterial species. CONCLUSION: Variation in the cytological differential counts and bacterial cultures of guttural pouch lavages may be found in clinically normal horses which have had their heads restrained in an elevated position for periods from 12 to 24 h. This should be considered when examining this site and care must be taken when interpreting cytology of guttural pouch lavages in samples taken after transportation for more than 12 h. Restriction of head movement could also affect the normal pouch enviroment and predispose it to disease.     

Ischemic optic neuropathy and blindness after arterial occlusion for treatment of guttural pouch mycosis in two horses

Ischemic optic neuropathy accompanied by blindness was induced in 2 horses after surgical occlusion of the external and internal carotid and greater palatine arteries, performed as part of the management of guttural pouch mycosis. The blindness was acute and unilateral and may have been caused by ischemic retinal damage. Vascular occlusion is a recommended procedure for treatment of guttural pouch mycosis. Retinal damage and blindness are a possible complication if all possible sources of hemorrhage are occluded.     

Complications associated with Streptococcus equi infection on a horse farm

Complications associated with Streptococcus equi infection developed in 15 (20.3%) of 74 horses on one farm included death, guttural pouch empyema, purpura hemorrhagica, upper respiratory tract obstruction, pneumonia, pleuropneumonia, agalactia, mesenteric lymph node abscessation, and periorbital abscessation. Death was attributed to pneumonia in 3 horses and to upper respiratory tract obstruction in 2 horses. One horse was euthanatized because of severe purpura hemorrhagica.     

A surgical approach to the lateral compartment of the equine guttural pouch in the standing horse: modification of the forgotten "Garm technique"

The objective of this study was to evaluate the feasibility, efficacy and complications following lavage and drainage of the lateral compartment (LC) of the equine guttural pouch (GP) using a modified Garm's technique (MGT). In an ex vivo study (study 1), six cadaver heads were examined to assess the anatomical limits of the surgical approach and whether vital structures might be damaged. This was followed by an in vivo study (study 2) in which a lavage/drainage tube was placed for 3 days into each LC of four standing horses using the MGT. In both studies, the procedure offered direct access into the LC and indirect access into the medial compartments of the GP. In study 1, the MGT provided a rostroventral point of access allowing drainage of the LC, with no obvious iatrogenic damage. In study 2, the MGT permitted lavage of the entire GP in three healthy horses and one horse with mild GP empyema. The only major complication was development of emphysema of the lateral wall of one LC, with secondary collapse of the mucous membrane. The time for secondary wound healing was 12-14 days. The MGT can be performed safely in standing horses and may be of value in providing access for lavage and drainage in horses with mild GP empyema.     

Guttural pouch empyema caused by Corynebacterium pseudotuberculosis in a pregnant mare

During medical management of mild colic in a 12‐year‐old Quarter Horse, mid‐gestation mare, unilateral purulent nasal discharge from the right nostril was noted. Endoscopic examination revealed guttural pouch empyema. Culture was positive for Corynebacterium pseudotuberculosis and negative for Streptococcus equi ssp. equi. A synergistic haemolysis inhibition titre of 1024 was consistent with C. pseudotuberculosis infection. Treatment included serial lavages and local infusion of antibiotics into the guttural pouches along with a 6‐week course of oral trimethoprim–sulfamethoxazole and rifampicin. Overall, no additional sites of infection were identified and the mare responded well to treatment, delivering a healthy, full‐term foal. This case emphasises that C. pseudotuberculosis, although uncommon, should be considered as a differential for guttural pouch empyema.     

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.     

Extensive and invasive guttural pouch granuloma in a 2-year-old gelding

This report describes a case of an unusually extensive and invasive fungal granuloma within the right guttural pouch and its surrounding area of a 2-year-old Noriker gelding, causing diverse neurogenic deficits and tissue destruction. The gelding was initially presented with cachexia, unilateral nasal discharge, intermittent fever, swelling of the right side of the head, facial nerve paralysis and dysphagia. The right guttural pouch was not accessible to endoscopic examination initially, but after anti-inflammatory medical management, empyema and an extensive, solid mass appeared within the guttural pouch. Surgical exploration and excision were attempted but were unsuccessful. Histopathological examination identified Aspergillus fumigatus as the causative infective agent of the extensive fungal granuloma, and the consequent invasion and destruction of surrounding bone and soft tissue structures.     

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.     

Balloon-tipped catheter arterial occlusion for prevention of hemorrhage caused by guttural pouch mycosis: 13 cases (1982-1985)

Epistaxis, caused by guttural pouch mycosis, was treated by balloon-tipped catheter and ligature occlusion of the involved arteries in 13 horses. In 7 horses, more than one artery was catheterized. Serious postoperative hemorrhage was prevented in all horses. Long-term endoscopic follow-up examination was possible in 8 horses, and all had complete regression of the fungal lesion as early as 5 weeks after surgery. Six of the 8 horses did not receive medical treatment. Problems related to the use of the balloon-tipped catheter technique were rare. There were incisional infections in 3 horses, catheter breakage during removal occurred twice, and in one horse, a catheter was inappropriately placed.     

Gutteral pouch tympany in German warmblood foals: influence of sex,inbreeding and blood proportions of founding breeds as well as estimation of heritability

The objective of the present study was to analyse the importance of the influences of sex, inbreeding coefficient, proportion of genes of the original breeds and the additive genetic contribution to the occurrence of guttural pouch tympany in foals belonging to German Warmblood breeds. Foals affected by guttural pouch tympany were ascertained in the Clinic of Horses, School of Veterinary Medicine Hannover. This data set comprised 22 German Warmblood foals with guttural pouch tympany, which were patients of the Clinic for Horses between 1994 and 2001. Information on the pedigrees and all available relatives of these patients allowed us to group the affected foals into five families with a total of 289 animals. Female foals were significantly more often affected by guttural pouch tympany. The difference was 16.6% in favour of female foals. The size of the inbreeding coefficient was not important for the occurrence of guttural pouch tympany. The proportion of the genes of the breeds Arabian, Thoroughbred and Trakehner were not significantly different from a randomly selected sample of 10% of foals born in the same birth years and the same region. The heritability estimates for the frequency of guttural pouch tympany using a threshold model was 0.81 +/- 0.16. This is the first report that could show a genetic component responsible for guttural pouch tympany in horses.     

Transarterial coil embolization of the internal and external carotid and maxillary arteries for prevention of hemorrhage from guttural pouch mycosis in horses

OBJECTIVES: To develop a transarterial coil embolization technique for occlusion of the internal carotid artery (ICA), external carotid artery (ECA), and maxillary arteries (MA) in normal horses and to evaluate this technique for prevention of hemorrhage in horses affected with guttural pouch mycosis. ANIMALS: Ten adult, normal horses and 4 horses with guttural pouch mycosis. METHODS: All horses had transarterial coil embolization of the rostral and caudal ICA, caudal MA, and rostral ECA. In 1 affected horse, an aberrant actively bleeding branch of the ECA was also occluded. Normal horses had a premortem angiogram, and were killed either at 1 or 2 weeks or 1, 2, or 3 months after the procedure. Specimens from the ICA, ECA and MA were evaluated by light microscopy. RESULTS: No surgical complications were observed, except 1 horse that developed laryngeal hemiplegia and 1 pilot horse that had embolization of the cerebral arterial circle. In normal horses, premortem angiography confirmed complete occlusion of all vessels, and coils were positioned as intended. All normal horses had partially maturing to mature, continuous thrombi occluding at the coils. In affected horses, no further episodes of epistaxis were observed. By day 60, all mycotic plaques had resolved without further treatment. Ophthalmic complications were not observed. CONCLUSION: Transarterial embolization provided a safe, rapid, and effective method for ICA, ECA, and MA occlusion in normal and affected horses. In affected horses, the technique was possible despite active bleeding, allowing adequate identification and occlusion of all sources of hemorrhage.     

Guttural pouch mycosis in two horses

The history and clinical findings of 1 horses with guttural pouch mycosis referred to us are described. The salient features of the history and clinical signs common to both cases were profuse spontaneous nasal haemorrhage, partial pharyngeal paralysis; subsequently bilateral nasal discharge containing food material, inability to drink and parotid pain became evident. One case made a gradual recovery with conservative medical treatment while the second case was destroyed and submitted for post-mortem, histopathological and microbiological examination. This examination failed to establish the initiating cause of the lesion but later stages were clearly associated with an invasive septate fungus morphologically resembling Aspergillus.     

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.