Henry D. O’Neill
Hemoptysis and Epistaxis
By definition, hemoptysis refers to the expectoration of blood-contaminated sputum from the lower respiratory tract (i.e., the trachea, bronchi, and lungs), whereas epistaxis refers simply to bleeding from the nostrils; this blood can originate from either the upper or lower parts of the respiratory tract. The underlying causes of such clinical signs are varied, and although some of these underlying conditions can readily be diagnosed in the field from a thorough history, physical examination, and some types of imaging, obtaining a definitive diagnosis in others may necessitate referral to hospitals offering advanced imaging techniques. Delays in reaching a diagnosis can potentially be fatal for some patients, as in the case of guttural pouch mycosis. Others may be low-risk, self-resolving conditions requiring minimal intervention (e.g., sinonasal trauma). Bleeding occurring after strenuous exercise is likely to be a result of exercise-induced pulmonary hemorrhage (EIPH), and is covered elsewhere in this book (see Chapter 58). This chapter covers the general principles applying to the examination and diagnostic stages of a typical horse with epistaxis, followed by an explanation of the specific diseases commonly encountered.
General Examination
Although no breed-specific causes of epistaxis occur in the horse, patient age can be suggestive of certain conditions. Fractious foals and young horses with a history of head trauma, falling over backward, acute onset of neurologic signs, or neck pain are more likely to have sinonasal trauma or rupture of the ventral straight muscles of the head (longus capitis and rectus capitis ventralis muscles). Progressive ethmoid hematomas appear to have a propensity (but not exclusivity) for developing in middle-aged horses, whereas underlying neoplastic conditions are more likely in the geriatric horse.
Distinguishing between unilateral and bilateral epistaxis can be helpful for approximating the origin of hemorrhage in the respiratory tract. The openings of the guttural pouch act as a good landmark, with hemorrhage arising rostral to them tending to be unilateral and sources arising caudal to the openings tending to be bilateral. Hemorrhage emanating from a single guttural pouch can manifest as either unilateral or bilateral epistaxis, with larger volumes tending to be associated with bilateral discharge.
Disappointingly, physical examination findings are often nonspecific in nature, with a few exceptions. Evidence of unilateral cranial nerve deficits or Horner’s syndrome (ptosis, miosis, enophthalmos, and hyperhidrosis of the head and neck) with concurrent episodes of epistaxis should prompt suspicion of guttural pouch mycosis. Sensitivity on palpation around the head or poll region can be suggestive of recent trauma. Likewise, pain on palpation of the parotid and cranial cervical region may suggest guttural pouch involvement. Reduced airflow from one or both nostrils can indicate an obstructive disorder in the nasal meati, but does not give any idea of the exact nature of obstruction. Additional diagnostic tests are therefore warranted in most cases.
Diagnostic Testing
Endoscopy
Endoscopic evaluation of the respiratory tract is readily performed and will yield a definitive diagnosis in a high percentage of cases, or at least indicate the anatomic region from which the hemorrhage is originating. The length and diameter of the flexible endoscope will determine the extent to which the tract can be examined, but for most adult horses, an endoscope 1.7 meters in length with a diameter of 10 millimeters is required to adequately view the respiratory tract from the nostrils to the tracheal bifurcation and mainstem bronchi. A thorough evaluation includes a detailed inspection of both nasal passageways; the dorsal, middle, and ventral meati; the ethmoid labyrinths; the nasomaxillary openings; the nasopharynx; the contents of the guttural pouches; the larynx, and the trachea and its bifurcation. Evidence of hemorrhagic or serohemorrhagic discharge from any location warrants closer investigation. Use of a guidewire advanced through the biopsy channel will assist in placement of the endoscope in the guttural pouches. The biopsy channel of the endoscope also permits sample collection for histologic evaluation in cases of unusual soft tissue masses.
Radiography
Radiographic examination of the upper (and to a lesser extent the lower) part of the respiratory tract is often performed in conjunction with endoscopy, with the two modalities complementing one another. With the advances made in mobile digital imaging equipment, most equine ambulatory clinicians are able to produce high-quality images of the head. Radiography provides a useful, noninvasive method of detailing the paranasal sinuses and associated osseous structures of the head, along with the nasopharyngeal area and laryngeal cartilages. Although high-quality images of the head can be obtained with relative ease, detection and interpretation of abnormalities can be more of a challenge, with lesions frequently superimposed over surrounding structures such as the globe, orbit, ethmoid turbinates, and normal intrasinus bony trabeculae. Orthogonal views can assist in localizing areas of pathologic change within the skull.
Sinoscopy
Sinoscopy describes the intraluminal imaging of the paranasal sinuses. In the past, rigid 4-mm arthroscopes were used, but now use of a flexible endoscope (diameter ≤ 10 mm) is more common and provides greater access to all regions around the sinus compartments. Sinoscopy is easily performed in the standing sedated horse and has been reported to yield a diagnosis in up to 70% of cases. Although multiple access points into the sinuses can be used, a good site for an initial portal is centered over the nasomaxillary opening—topographically, this lies midway between the medial canthus of the eye and midline of the skull. Complete descriptions of the technique can be found in Chapter 50. The technique is more useful in older horses, in which the sinus compartments have enlarged because of eruption of reserve tooth crowns, and also in horses in which the lesion does not completely obliterate all free space. Information obtained from the examination may enable the obtaining of biopsy specimens for further analysis, or extension of the trephine site into a complete sinus flap for full surgical exploration. The author has now moved away from performing this procedure, opting instead to proceed with a small bone flap because the interventional treatment that is invariably required is easier and more rapidly performed through a slighter larger hole, and this technique has a comparable cosmetic outcome.
Advanced Imaging
In cases in which the diagnosis or lesion distribution is still uncertain, magnetic resonance imaging (MRI) and computed tomography (CT) provide excellent imaging of the head, with the latter now being offered as a standing procedure at some referral hospitals. Given the limitations associated with the sizes of both the machines and adult horse, both modalities are only able to image from the nostrils as far caudal as the proximal cervical region. Scintigraphy is another highly sensitive imaging technique, allowing detection of areas of bone remodeling. It does, however, lack specificity.
Conditions
Progressive Ethmoid Hematoma
Progressive ethmoid hematoma (PEH) is a nonneoplastic expansile mass, usually located in the ethmoidal labyrinth, although some lesions can originate from or extend into the paranasal sinuses. Most affected horses have a history of intermittent, unilateral, serosanguineous nasal discharge. Epistaxis is generally not a feature seen with this disease. Discharges may occur spontaneously or after exercise, so EIPH should be ruled out as a concurrent disease. Other clinical signs may include bilateral nasal discharge, reduced nasal airflow, facial deformity, fetid odors, and respiratory or exercise intolerance. Despite their characteristic appearance and location, how PEHs originate remains ambiguous. It is speculated that repeated episodes of hemorrhage into the submucosa of the respiratory epithelium slowly enlarge the mass size. A recent retrospective study of the condition indicated that Thoroughbreds and geldings are overrepresented, with affected horses ranging from 3 to 20 years in age (mean, 12 years); however, the condition has also been described in females, foals, and other breeds. Lesions do not metastasize to remote body sites but are locally destructive as a result of their expanding size, and it is not uncommon to find multiple concurrent nasal or paranasal masses on examination.
Diagnosis
If present within the nasal passageway or ethmoid labyrinth, lesions should be visible endoscopically. Their spherical appearance and green-yellow capsule distinguishes them from normal tissue. For lesions inside the paranasal sinuses, radiography can be helpful if the mass is large enough to be visible. However, if the lesion is very small, or if the sinus cavity is filled with material of soft tissue density or fluid, an exploratory sinusotomy may be the only way to reach a definitive diagnosis. Noninvasive imaging such as MRI or CT can prove a very useful alternative, offering the best images of areas difficult to view, such as the sphenopalatine sinus. In a retrospective study, PEHs were identified radiographically in 15 of 16 horses. However, in five of the cases, the lesion location was incorrectly predicted. Also, bilateral disease was detected in only two of eight cases in which it occurred. This highlights the importance of advanced imaging before surgery. Differential diagnoses include other conditions that may give rise to persistent or intermittent epistaxis, such as EIPH, ulcerative or fungal rhinitis, foreign bodies, ethmoid neoplasia, mycosis or neoplasia of the guttural pouch, skull fracture, neoplasia, infection or cyst of the paranasal sinuses, pulmonary abscess or neoplasia, and infectious pleuropneumonia.
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