• View in gallery

    Illustration of surgical fenestration within the region of the dorsal pharyngeal recess. A—Initial incision created on midline with diode laser. The outer borders of the planned bilateral incisions are indicated in blue dashed lines. The dorsal lines highlight the region just ventral to the salpingopharyngeal plica. B—The triangular-shaped bilateral incisions reveal the median septum of the guttural pouch. C—The median septum is grasped with laryngeal forceps and pulled to the right; a vertical hemi-elliptical resection indicated by a blue dashed line is completed with the diode laser.

  • View in gallery

    Endoscopic images captured during surgical fenestration of the right guttural pouch. A—Diode laser excision of the dorsal arm of the triangle to connect vertical midline and ventral incisions. B—Purulent debris is now visible within the right guttural pouch. Note that thickened mucosa often accompanies chronic infection. C—Active lavage of right guttural pouch contents facilitated by uterine infusion pipette inserted via pharyngeal ostium (lower left aspect of photograph). D—View of triangular fenestration following lavage and evacuation of purulent debris.

  • View in gallery

    Right guttural pouch pharyngeal fenestration from the horse depicted in Figure 2. The diverticulotomy is patent and permitting pouch egress 90 days following surgery.

  • 1.

    Freeman DE. Guttural pouch. In: Auer JA, Stick JA, Kümmerle JM, et al., eds. Equine Surgery. 5th ed. WB Saunders; 2019:770796.

  • 2.

    Davis E. Disorders of the respiratory system. In: Reed SM, Bayly WM, Sellon DC, eds. Equine Internal Medicine. 4th ed. WB Saunders; 2018:313386.

    • Search Google Scholar
    • Export Citation
  • 3.

    Newton JR, Wood JL, Dunn KA, DeBrauwere MN, Chanter N. Naturally occurring persistent and asymptomatic infection of the guttural pouches of horses with Streptococcus equi. Vet Rec. 1997;140(4):8490.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 4.

    Judy CE, Chaffin MK, Cohen ND. Empyema of the guttural pouch (auditory tube diverticulum) in horses: 91 cases (1977–1997). J Am Vet Med Assoc. 1999;215(11):16661670.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 5.

    Adkins AR, Yovich JV, Colbourne CM. Nonsurgical treatment of chondroids of the guttural pouch in a horse. Aust Vet J. 1997;75(5):332333.

    • Search Google Scholar
    • Export Citation
  • 6.

    Freeman DE. Complications of surgery for diseases of the guttural pouch. Vet Clin North Am Equine Pract. 2008;24(3):485497.

  • 7.

    Tate LP Jr, Blikslager AT, Little ED. Transendoscopic laser treatment of guttural pouch tympanites in eight foals. Vet Surg. 1995;24(5):367372.

  • 8.

    Tetens J, Tulleners EP, Ross MW, Orsini PG, Martin BB Jr. Transendoscopic contact neodymium:yttrium aluminum garnet laser treatment of tympany of the auditory tube diverticulum in two foals. J Am Vet Med Assoc. 1994;204(12):19271929.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 9.

    Hawkins JF, Frank N, Sojka JE, Levy M. Fistulation of the auditory tube diverticulum (guttural pouch) with a neodymium:yttrium-aluminum-garnet laser for treatment of chronic empyema in two horses. J Am Vet Med Assoc 2001;218(3):405407, 361.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 10.

    Watkins AR, Parente EJ. Salpingopharyngeal fistula as a treatment for guttural pouch mycosis in seven horses. Equine Vet J. 2018;50(6):781786.

  • 11.

    Koch DW, Easley JT, Nelson BB, Delcambre JJ, McCready EG, Hackett ES. Comparison of two techniques for transpharyngeal endoscopic auditory tube diverticulotomy in the horse. J Vet Sci. 2018;19(6):835839.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 12.

    Ducharme NG, Cheetham J. Pharynx. In: Auer JA, Stick JA, Kümmerle JM, et al., eds. Equine Surgery. 5th ed. WB Saunders; 2019:710733.

  • 13.

    Deluzurieux M, Desjardins I, Nolf M, Guidi E. Endoscopic analysis of guttural pouch opening in horses. J Exp Appl Anim Sci. 2013;1(1):1024.

    • Search Google Scholar
    • Export Citation
  • 14.

    Dixon PM, James OA. Equine guttural pouch empyema, why does it become chronic? Equine Vet Educ. 2018;30(2):8084.

  • 15.

    Baptiste K. Functional anatomy observations of the pharyngeal orifice of the equine guttural pouch (auditory tube diverticulum). Vet J. 1997;153(3):311319.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 16.

    Jukic CC, Cowling NR, Perkins NR, van Eps AW, Ahern BJ. Evaluation of the effect of laser salpingopharyngostomy on the guttural pouch environment in horses. Equine Vet J. 2020;52(5):752759.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 17.

    Freeman DE. Update on disorders and treatment of the guttural pouch. Vet Clin North Am Equine Pract. 2015;31(1):6389.

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Clinical outcome of horses with guttural pouch infection following transpharyngeal fenestration

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  • 1 Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO

Abstract

OBJECTIVE

To report the clinical outcomes of horses with chronic guttural pouch infection characterized by accumulation of mucopurulent material following transpharyngeal diode laser fenestration.

ANIMALS

13 client-owned horses

PROCEDURES

Horses undergoing diode laser fenestration for chronic guttural pouch infection were identified by medical record search. Signalment, disease history, presence of mucopurulent empyema or chondroids, and pre- and postoperative therapy were recorded. Owners were contacted for follow-up information at a minimum of 6 months following surgery.

RESULTS

13 horses underwent laser fenestration for chronic guttural pouch infection. Thirteen had mucopurulent nasal discharge on presentation, and 3 were coughing. At follow-up, 12 horses treated with transpharyngeal diode laser fenestration had complete resolution of nasal discharge and coughing. One horse, despite resolution of guttural pouch infection on endoscopy, continued to have nasal discharge and coughing attributed to concurrent equine asthma syndrome. All owners expressed satisfaction with the surgical procedure and clinical resolution of guttural pouch infection.

CLINICAL RELEVANCE

This surgical technique for transpharyngeal diode laser fenestration of the guttural pouch was uncomplicated to perform and well tolerated in sedated horses and attributed to resolution of clinical signs associated with guttural pouch infection, and owners reported a high satisfaction with the clinical outcome. Implementing this surgical technique could be considered to hasten resolution of chronic guttural pouch disease in horses with few technique-related complications.

Abstract

OBJECTIVE

To report the clinical outcomes of horses with chronic guttural pouch infection characterized by accumulation of mucopurulent material following transpharyngeal diode laser fenestration.

ANIMALS

13 client-owned horses

PROCEDURES

Horses undergoing diode laser fenestration for chronic guttural pouch infection were identified by medical record search. Signalment, disease history, presence of mucopurulent empyema or chondroids, and pre- and postoperative therapy were recorded. Owners were contacted for follow-up information at a minimum of 6 months following surgery.

RESULTS

13 horses underwent laser fenestration for chronic guttural pouch infection. Thirteen had mucopurulent nasal discharge on presentation, and 3 were coughing. At follow-up, 12 horses treated with transpharyngeal diode laser fenestration had complete resolution of nasal discharge and coughing. One horse, despite resolution of guttural pouch infection on endoscopy, continued to have nasal discharge and coughing attributed to concurrent equine asthma syndrome. All owners expressed satisfaction with the surgical procedure and clinical resolution of guttural pouch infection.

CLINICAL RELEVANCE

This surgical technique for transpharyngeal diode laser fenestration of the guttural pouch was uncomplicated to perform and well tolerated in sedated horses and attributed to resolution of clinical signs associated with guttural pouch infection, and owners reported a high satisfaction with the clinical outcome. Implementing this surgical technique could be considered to hasten resolution of chronic guttural pouch disease in horses with few technique-related complications.

Introduction

The guttural pouch (auditory tube diverticulum) of the horse is a paired extension of the eustachian tube separated from the pharynx by the plica salpingopharyngea and fibrocartilaginous lamina.1 Local infection by Streptococcus equi can lead to cough, pyrexia, and nasal discharge, with lymph node abscessation and rupture leading to accumulation of purulent debris within the guttural pouch.2 With supportive care, affected animals typically improve within a few weeks.2 However, a small number of horses will become chronically infected or reservoirs for horse-to-horse transmission through long-term bacterial colonization of the guttural pouch.3 The source of chronic infection is a collection of purulent debris within the pouches (empyema) that can become inspissated over time (chondroids). Reservoir animals are of clinical and biosecurity concern, as they can be a source of widespread infection to naïve animals.2 Therefore, treatment of chronically infected animals focuses on resolution of indwelling purulent debris to prevent further transmission and clear the infection.

Previous reports have examined medical therapy and describe success with long-term lavage and topical antibiotic therapy unless disease had progressed to the formation of chondroids.4,5 Judy et al4 detected chondroids in 21% (19/91) of horses affected and found those horses were significantly more likely to respond poorly to medical therapy and require surgical intervention. When surgical intervention was warranted, previous techniques implemented transcutaneous incisions to gain access to the guttural pouch. With the transcutaneous guttural pouch approach, there is risk of iatrogenic nerve damage and need for postoperative wound management to facilitate lavage and drainage.6 Techniques using endoscopy-guided transpharyngeal laser energy have been developed to create a fenestration into the guttural pouch, often referred to as salpingopharyngostomy, to facilitate removal and speed drainage of purulent material, relieve increased pressure due to guttural pouch tympany, and modify the guttural pouch’s environment for treatment of mycosis, all while avoiding the aforementioned challenges of an open transcutaneous surgical approach.711 A distinct advantage of the transpharyngeal approach is that it can be readily performed with the horse standing, avoiding general anesthesia. Detailed description of this surgical technique applied to clinical cases with chronic guttural pouch infection has not been published. The objective of this case series was to report clinical outcomes of chronic guttural pouch infection in horses following treatment with transpharyngeal diode laser fenestration. We hypothesized that treatment of chronic guttural pouch infection with diode laser fenestration would be easy to perform, have minimal complications, and resolve guttural pouch disease.

Materials and Methods

A search was conducted of the electronic medical record system at Colorado State University’s Veterinary Teaching Hospital for equine cases that presented for endoscopic evaluation of the upper respiratory tract or presented for guttural pouch disease from June 2017 to June 2020. Horses were included if transpharyngeal diode laser fenestration was performed in 1 or both pouches to treat guttural pouch infection. Horses that did not undergo fenestration were excluded. Signalment, history, perioperative medications, bacterial culture, and affected guttural pouches were included.

Surgical treatment

The following surgical technique was used, as described below. Horses were sedated with detomidine hydrochloride (0.01 to 0.1 mg/kg, IV) and butorphanol tartrate (0.01 mg/kg, IV) and allowed to stand freely in a stall. Local anesthetic was not utilized. A flexible video endoscope (9 mm X 150 cm) was inserted into the contralateral ventral nasal meatus of the affected guttural pouch. Once within the nasopharynx, the dorsal pharyngeal recess and nasopharyngeal ostium of the affected side were viewed. A 600-μm quartz fiber, attached to a 980-nm-wavelength surgical diode laser, was inserted through the working channel of the endoscope and into the nasopharynx. By use of the laser fiber in contact fashion at 25 W, a triangular incision was created starting with a vertical midline incision the length of the dorsal pharyngeal recess (Figure 1). Successive passes of the laser fiber were made until a full-thickness incision was obtained through the guttural pouch mucosa, confirmed by further insertion of the endoscope via the incision and subsequent viewing of the pouch structures or purulent debris (Figure 2). The incision was continued from the dorsal extent of the vertical incision laterally across the nasopharyngeal wall of the affected side and finished at least 2 cm caudal to the observable nasopharyngeal ostium. The incision was created just ventral to the salpingopharyngeal plica to prevent incising the underlying fibrocartilaginous flap and allow direct pouch entry. The triangular fenestration was completed with a third incision connecting the ventral extent of the vertical midline incision to the rostral extent of the second. Each side of the triangle was estimated to be at least 2 cm in length. In cases for which bilateral fenestration was performed, a hemi-elliptical resection of the median septum adjacent to the dorsal pharyngeal recess wall was performed to ensure communication of both pouches to the nasopharynx (Figure 1). Equine laryngeal forceps were inserted within the ipsilateral ventral nasal meatus, the center of the triangular piece of tissue was grasped, and any final attachments to the underlying mucosa were transected with the laser while the tissue was under tension. The forceps were removed, a bent mare uterine infusion pipette was placed through the ipsilateral nasal meatus and into the fenestration, and lavage of the guttural pouch was conducted by use of a fluid pump and sterile isotonic saline (0.9% NaCl) solution delivered via the pipette. Lavage was continued until the majority of the purulent material or chondroids were removed when viewed endoscopically through the fenestration. Following surgery, horses were continued on trimethoprim-sulfamethoxazole 960-mg tablets (30 mg/kg, PO, q 12 h) for 7 to 14 days and flunixin meglumine (1.1 mg/kg, PO, q 12 to 24 h) for 3 to 5 days. Repeat endoscopy and second lavage were rarely necessary to confirm complete removal of pouch contents, and this was performed the following day at the discretion of the attending clinician. Recheck endoscopy was recommended postoperatively to evaluate health of the guttural pouch pending resolution of clinical signs. At discharge, no specific wound care instructions were advised.

Figure 1
Figure 1

Illustration of surgical fenestration within the region of the dorsal pharyngeal recess. A—Initial incision created on midline with diode laser. The outer borders of the planned bilateral incisions are indicated in blue dashed lines. The dorsal lines highlight the region just ventral to the salpingopharyngeal plica. B—The triangular-shaped bilateral incisions reveal the median septum of the guttural pouch. C—The median septum is grasped with laryngeal forceps and pulled to the right; a vertical hemi-elliptical resection indicated by a blue dashed line is completed with the diode laser.

Citation: Journal of the American Veterinary Medical Association 260, 10; 10.2460/javma.22.01.0041

Figure 2
Figure 2

Endoscopic images captured during surgical fenestration of the right guttural pouch. A—Diode laser excision of the dorsal arm of the triangle to connect vertical midline and ventral incisions. B—Purulent debris is now visible within the right guttural pouch. Note that thickened mucosa often accompanies chronic infection. C—Active lavage of right guttural pouch contents facilitated by uterine infusion pipette inserted via pharyngeal ostium (lower left aspect of photograph). D—View of triangular fenestration following lavage and evacuation of purulent debris.

Citation: Journal of the American Veterinary Medical Association 260, 10; 10.2460/javma.22.01.0041

Follow-up

Postoperative exams and endoscopy reports were recorded from the electronic medical record when present. Owner-reported follow-up by telephone was obtained for all horses a minimum of 6 months following surgery to determine the postoperative health of the horse including any owner-noted complications, description of current clinical signs if present, and owner’s level of satisfaction with treatment of their horse.

Descriptive statistics were performed by use of commercially available software (Prism version 8; GraphPad Software). Results were reported as median and range.

Results

Thirteen horses were identified that underwent transpharyngeal laser fenestration for guttural pouch infection from August 2017 to August 2020. Nine Quarter Horses, 1 American Paint Horse, 1 pony, 1 Appaloosa, and 1 Mustang were included. Median age was 9 years old (range, 1 to 22 years) and median weight 475 kg (range, 275 to 550 kg).

Medical history

Median duration of clinical signs prior to fenestration was 28 weeks (range, 2 to 144 weeks). Clinical signs of presenting horses included uni- or bilateral mucopurulent nasal discharge (n = 13), coughing (3), submandibular lymphadenopathy (2), and bulging of the pharyngeal wall on endoscopy (2). Of the 13 horses identified that underwent fenestration, 8 had bilateral and 5 had unilateral disease (right sided in 4 and left sided in 1). Guttural pouch infection was characterized by accumulation of mucopurulent discharge (empyema) in the affected pouch or pouches of 4 horses, while 9 horses contained inspissated mucopurulent material (chondroids). Purulent material from the guttural pouch of 10 horses was submitted for bacterial culture and PCR; Streptococcus equi subsp equi was isolated from 9 horses, and Streptococcus equi subsp zooepidemicus was isolated from 1 horse. Prior to diode laser fenestration, medical treatment of horses included antibiotics (n = 8), systemic nonsteroidal anti-inflammatory drugs (10), systemic steroids (3), endoscopic-assisted lavage of the guttural pouch with sterile isotonic saline solution (4), local antibiotic therapy of the guttural pouch (2), or no prior medications (3).

Outcome

Horses underwent unilateral (n = 5) or bilateral (8) diode laser fenestration by use of the described technique, and the procedures performed adhered to hospital guidelines for biosecurity. Surgery with lavage was completed at a single hospital visit as an outpatient procedure in 11 horses. One horse was hospitalized to allow repeat postoperative lavage the following day. Another horse underwent 2 outpatient lavage attempts prior to hospitalization and fenestration. In this horse, the right guttural pouch fenestration site was enlarged the day following surgery to facilitate egress of remaining chondroids. All purulent material and chondroids were removed by means of lavage facilitated by the fenestration prior to hospital discharge. No intraoperative complications were recorded that required cessation of the surgical procedure or other medical intervention. One horse that had severe nasopharyngeal collapse from marked guttural pouch fill due to chondroids underwent temporary tracheotomy. Eight of 13 horses underwent postoperative endoscopy (median, 19 days; range, 1 to 90 days), which confirmed resolution of disease and continued fenestration patency (Figure 3).

Figure 3
Figure 3

Right guttural pouch pharyngeal fenestration from the horse depicted in Figure 2. The diverticulotomy is patent and permitting pouch egress 90 days following surgery.

Citation: Journal of the American Veterinary Medical Association 260, 10; 10.2460/javma.22.01.0041

Median time to owner-reported follow-up via telephone was 74 weeks (range, 24 to 123 weeks) post surgery. At the time of contact, 12 horses had full resolution of clinical signs including nasal discharge and cough. An owner of 2 horses reported occasional coughing and noticed chondroids on the ground of the stall of each horse within 7 days of the surgery. Both fully resolved without further treatment. In 1 horse, the owner noted persistent mild respiratory noise during exercise that did not affect athletic performance under saddle. The horse with continued clinical signs had concurrent diagnosis of equine asthma syndrome and sustained persistent postoperative nasal discharge and a cough despite systemic steroid treatment. However, endoscopy 7 days following surgery in this horse confirmed both guttural pouches to be free of purulent material. All 13 owners were satisfied with the ease of postoperative management, absence of perioperative complications, and resolution of clinical signs.

Discussion

To our knowledge, this was the first report of endoscopic-assisted transpharyngeal laser fenestration of the guttural pouch, including detailed descriptions of this surgical technique, applied to clinical cases with chronic guttural pouch infection. The procedure was easy to perform and was not associated with material operative complications. This technique for diode laser fenestration of the guttural pouch led to resolution of clinical signs including nasal discharge and coughing in the majority of horses, with apparent resolution of guttural pouch infection in all horses that underwent the procedure. Limited required postoperative aftercare combined with resolution of disease likely contributed to the high owner satisfaction associated with the procedure.

Resolution of clinical signs following fenestration implies that lack of egress is an essential mechanism in maintaining chronic guttural pouch infection. Inflammation of the mucosal lining that occurs with local infection can lead to neuritis of the pharyngeal branch of the vagus nerve and loss of muscular control of the nasopharyngeal ostium.1,2,12,13 This inflammation also contributes to loss of the normal mucociliary clearance and thickening of exudate with infiltrating leukocytes.14 Further, overinflation of the guttural pouch with continued distension can also inhibit fluid egress.15 Therefore, purulent debris within the guttural pouch not only prevents outflow due to direct obstruction but likely induces neuritis-related nasopharyngeal ostium dysfunction and development of a chronic disease state. For these reasons, we believe fenestration facilitates egress of the guttural pouch following surgery in spite of this dysfunction, hastens resolution of infection, and subsequently improves the local guttural pouch environment. With recent evidence pointing to changes in guttural pouch carbon dioxide and oxygen levels postfenestration, alteration of the guttural pouch microenvironment could also be of benefit as drainage and resolution occur.16 While it cannot be stated definitively that surgical intervention was the sole reason for improvement, clinical signs of substantial duration were abrogated following fenestration and removal of purulent debris. Therefore it appears plausible that improved drainage following surgical intervention could lead to resolution of nasal discharge and coughing as noted within this population of horses undergoing diode laser fenestration.

Although rare, chronically infected or carrier animals that do not show outward clinical signs of S equi infection can serve as reservoir hosts when introduced into a naïve herd.3 While supportive care with strict isolation from other animals is usually sufficient for treatment, we set out to hasten disease resolution in chronically infected horses with clinical signs. Additionally, as most horses were culture and PCR positive for the subspecies of streptococcus known to cause “strangles,” treatment to expedite removal of purulent debris was warranted before each horse returned to its herd. Therefore, it is also critical to include biosecurity in the hospital care plan for these animals, as in the present report. Traditional treatment of guttural pouch infection has relied on high volume lavage and local administration of medications.17 However, to access the guttural pouch for visualization and treatment, instruments must be repeatedly inserted through the nasopharyngeal ostium. This leads to visible trauma, exacerbates local inflammation, and inhibits normal egress due to ostium stenosis, leading to chronic guttural pouch infection.14 However, following transpharyngeal fenestration, traversing the natural orifice is no longer required, as instruments can instead be introduced directly into the guttural pouch, avoiding further trauma to the nasopharyngeal ostia and its cartilaginous plica. Transpharyngeal diode laser fenestration allowed for more direct access to the guttural pouch than the natural opening due to location and size. Furthermore, it appeared that fenestration-facilitated egress hastened resolution of mucosal inflammation, which likely improved the guttural pouch microenvironment and its innate ability to resolve local bacterial infection. More work is needed to determine if this technique could be beneficial in reducing long-term reservoir hosts of S equi subsp equi that occur with guttural pouch infection and whether previously positive horses would have a negative PCR following treatment compared to other regimens.

Historically, surgical treatment for guttural pouch infection has included transcutaneous incisions, considered to increase risk of iatrogenic nerve damage leading to permanent neurologic deficits such as dysphagia.6 These open incisional wounds also require postoperative wound care, with concern for localized surgical site infection. Surgical transcutaneous placement of indwelling tubes to facilitate further drainage can result in pain, swelling, and extension of local infection.14 A benefit of creating a salpingopharyngostomy, salpingopharyngeal fistula, or diverticulotomy utilizing a transpharyngeal approach is reduced risk of iatrogenic neurovascular injury as the guttural pouch is approached via the rostral and dorsal aspect.6 An additional benefit to caregivers is the lack of an open, contaminated external wound following surgery. This likely contributed to high owner satisfaction with the procedure, along with improved clinical signs following surgery.

We reported here a technique for transpharyngeal diode laser fenestration of the guttural pouch that was easy to perform and well tolerated. In the majority of horses that underwent fenestration, both nasal discharge and coughing resolved. We believe this technique allows for continuous egress of mucopurulent debris from the guttural pouch following fenestration, improving health of the region. Controlled study of this chronic condition is difficult, and whether another or no treatment could result in similar resolution is a limitation of retrospective study. Further studies are needed to elucidate which cases are best selected for surgical versus medical therapy alone. Future work will examine how induced ostia dysfunction contributes to inadequate fluid egress as a model for studying chronic guttural pouch infection.

Acknowledgments

Stipend support for Dr. Koch was provided by NIH 5T32 OD011130-13.

The authors declare that there were no conflicts of interest.

References

  • 1.

    Freeman DE. Guttural pouch. In: Auer JA, Stick JA, Kümmerle JM, et al., eds. Equine Surgery. 5th ed. WB Saunders; 2019:770796.

  • 2.

    Davis E. Disorders of the respiratory system. In: Reed SM, Bayly WM, Sellon DC, eds. Equine Internal Medicine. 4th ed. WB Saunders; 2018:313386.

    • Search Google Scholar
    • Export Citation
  • 3.

    Newton JR, Wood JL, Dunn KA, DeBrauwere MN, Chanter N. Naturally occurring persistent and asymptomatic infection of the guttural pouches of horses with Streptococcus equi. Vet Rec. 1997;140(4):8490.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 4.

    Judy CE, Chaffin MK, Cohen ND. Empyema of the guttural pouch (auditory tube diverticulum) in horses: 91 cases (1977–1997). J Am Vet Med Assoc. 1999;215(11):16661670.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 5.

    Adkins AR, Yovich JV, Colbourne CM. Nonsurgical treatment of chondroids of the guttural pouch in a horse. Aust Vet J. 1997;75(5):332333.

    • Search Google Scholar
    • Export Citation
  • 6.

    Freeman DE. Complications of surgery for diseases of the guttural pouch. Vet Clin North Am Equine Pract. 2008;24(3):485497.

  • 7.

    Tate LP Jr, Blikslager AT, Little ED. Transendoscopic laser treatment of guttural pouch tympanites in eight foals. Vet Surg. 1995;24(5):367372.

  • 8.

    Tetens J, Tulleners EP, Ross MW, Orsini PG, Martin BB Jr. Transendoscopic contact neodymium:yttrium aluminum garnet laser treatment of tympany of the auditory tube diverticulum in two foals. J Am Vet Med Assoc. 1994;204(12):19271929.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 9.

    Hawkins JF, Frank N, Sojka JE, Levy M. Fistulation of the auditory tube diverticulum (guttural pouch) with a neodymium:yttrium-aluminum-garnet laser for treatment of chronic empyema in two horses. J Am Vet Med Assoc 2001;218(3):405407, 361.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 10.

    Watkins AR, Parente EJ. Salpingopharyngeal fistula as a treatment for guttural pouch mycosis in seven horses. Equine Vet J. 2018;50(6):781786.

  • 11.

    Koch DW, Easley JT, Nelson BB, Delcambre JJ, McCready EG, Hackett ES. Comparison of two techniques for transpharyngeal endoscopic auditory tube diverticulotomy in the horse. J Vet Sci. 2018;19(6):835839.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 12.

    Ducharme NG, Cheetham J. Pharynx. In: Auer JA, Stick JA, Kümmerle JM, et al., eds. Equine Surgery. 5th ed. WB Saunders; 2019:710733.

  • 13.

    Deluzurieux M, Desjardins I, Nolf M, Guidi E. Endoscopic analysis of guttural pouch opening in horses. J Exp Appl Anim Sci. 2013;1(1):1024.

    • Search Google Scholar
    • Export Citation
  • 14.

    Dixon PM, James OA. Equine guttural pouch empyema, why does it become chronic? Equine Vet Educ. 2018;30(2):8084.

  • 15.

    Baptiste K. Functional anatomy observations of the pharyngeal orifice of the equine guttural pouch (auditory tube diverticulum). Vet J. 1997;153(3):311319.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 16.

    Jukic CC, Cowling NR, Perkins NR, van Eps AW, Ahern BJ. Evaluation of the effect of laser salpingopharyngostomy on the guttural pouch environment in horses. Equine Vet J. 2020;52(5):752759.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 17.

    Freeman DE. Update on disorders and treatment of the guttural pouch. Vet Clin North Am Equine Pract. 2015;31(1):6389.

Contributor Notes

Corresponding author: Dr. Hackett (eileen.hackett@cornell.edu)