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When is nasal discharge more than just nasal discharge.

Nasal discharge can represent something benign, life threatening, or anything in between. Often horses are placed on antimicrobials for any nasal discharge because of limited ability to evaluate the problem and effectively treating the horse, but with advanced diagnostic imaging and newer surgical techniques the effectiveness of treating such patients has improved dramatically.

In most cases nasal discharge is not an emergency, but any horse with nasal hemorrhage should be evaluated immediately. While bilateral epistaxis is most commonly from exercise induced pulmonary hemorrhage and not life threatening, a severe bleed from the guttural pouch could be from one or both nares and is life threatening. Guttural pouch hemorrhage is most often the result of a mycotic infection eroding through major arteries in the pouch lining. A large volume of blood evident on endoscopic examination at the guttural pouch opening is often the only evidence needed prior to referral for surgery. Trying to endoscopically evaluate the inside of the guttural pouch close to the time of a severe bleed is usual futile since the amount of blood within the pouch will obscure visualization. Surgery is aimed at obstructing blood flow through the major vessels in the lining of the guttural pouch. Ligation at the cardiac side as a sole procedure is often ineffective because of retrograde flow, so the vessels must be obstructed or embolized on the cranial side as well. If there is not an opportunity to obstruct vessel cranial to the lesion, ligation at the cardiac side can be effective in a small percentage of horses. The surgery not only prevents further hemorrhage but also causes the mycotic lesions to resolve without any medical therapy. Any evidence of neurologic disease (laryngeal dysfunction or dysphagia) should be determined prior to surgery.

Other causes of epistaxis to consider are trauma, neoplasia, fungal infections, or ethmoid hematomas. All of these are typically of a much lower volume relative to guttural pouch mycosis. Severe trauma can result in avulsion of the longus capitis muscle from the insertion of the basisphenoid bone and moderate bleeding from the guttural pouch. Blood seen from the nasomaxillary opening can be secondary to trauma and bleeding into the sinus without external signs of trauma. Radiographs will often reveal a fluid line. Treatment is not necessary, but antimicrobial treatment is recommended to prevent secondary sinusitis. Neoplasia or fungal infections that cause epistaxis are usually seen easily on endoscopic examination and are often mixed with purulent discharge. Treatment of neoplasia is often unrewarding but fungal infections can be treated effectively with topical anti-fungals if a method to ensure long contact time is instituted.

Progressive ethmoid hematomas causing epistaxis are very common. Unlike guttural pouch mycosis, hematomas typically cause a small volume, intermittent bleed not associated with exercise. It is extremely rare to have facial deformity and the source of bleeding could be within the nasal passage (ethmoid recess), within the sinuses, or both. Both endoscopic and radiographic evaluations are essential to fully appreciate the extent of the lesion, since they can often be in multiple sites. Small lesions can also exist within the sinus without obvious radiographic abnormalities, so caution must be used in interpretation of radiographs.

In many cases therapy may consist of intralesional formalin injections under endoscopic guidance in the standing horse on an outpatient basis. While this technique is very client/patient friendly and effective at abating clinical signs, it is unlikely to provide a "cure." Previous reports of success have been based on telephone follow up and not follow up endoscopy or radiography. Many patients have recurrence after several years and it may be in part because what we see within the nasal passage is just the tip of the lesion and we are not effectively treating the base or origin. Laser ablation may be more effective than intralesional formalin, but would require significantly more expense and repeated treatments with large lesions. For this reason, laser treatment is usually reserved for the smaller lesions. Our current treatment regimen for hematomas within the ethmoid recess is to treat with intralesional formalin at 4 week intervals until they are <1cm in diameter and then perform laser ablation. Hematomas within the sinus are managed differently.

Purulent discharge usually represents response to bacterial infection of the guttural pouch or sinus cavities. Discharge at the opening of the guttural pouch can be pushed into the opening during swallowing and may not represent a guttural pouch infection. Endoscopic examination of the pouch is necessary to refute or confirm the pouch as the origin. Discharge from the sinus cavity can often be seen dripping over the ventral turbinate from the nasomaxillary opening above. Complete examination of the ventral and middle meatus is recommended since infrequently a separate opening into the nasal cavity may present, or the material becomes so inspissated that the material becomes contained entirely within the middle meatus. Primary bacterial infections of the sinus without an underlying cause are common. Many patients will respond favorably to antimicrobial therapy without further diagnostics or treatment. Long term antimicrobials are usually required and if there is not an immediate response, further evaluation should be performed.

Radiography is commonly the next diagnostic procedure performed. If there is soft tissue density not consistent with a fluid line, or abnormalities with the teeth, referral should be considered. If the only radiographic abnormality is the presence of fluid within the sinus, then culture and lavage can be performed in the standing horse. A small trephine hole just rostral and ventral to the eye will allow placement of a teat cannula for aspiration and lavage. The only potential disadvantage is if the surgical site becomes a nidus of infection. Reasons against standing culture and lavage would be any radiographic indications of abnormalities not consistent with a primary sinusitis. Oral examination should be complementary to the endoscopic and radiographic evaluations to determine if any teeth abnormalities are resulting in a secondary sinusitis. When available, computed tomography provides much more information than radiography and more frequently is being used instead of any radiographs.

Eric J. Parente [1], DVM Dipl. ACVS

[1] New Bolton Center, Univ. of Pennsylvania, Kennett Square PA.
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Title Annotation:I. Conferencias magistrales
Author:Parente, Eric J.
Publication:Revista CES Medicina Veterinaria y Zootecnia
Date:May 1, 2018
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