BASICS
Fluid discharge of varying turbidity, color, amount, frequency, and odor from 1 or both nostrils.
- Composed of combinations of leukocytes and varying amounts of fluid and mucus from any location in the respiratory tract
- Production originates from an inflammatory process incited by traumatic, immune, allergic, infectious, or noxious stimuli
- Discharge can be septic or nonseptic
- Color varies—white, yellow, green, reddish, or brown depending on the presence of bacteria, ingesta, blood, or necrotic tissue
- Unilateral discharge is most likely associated with a condition of the ipsilateral nasal cavity or paranasal sinus
- Bilateral discharge more likely originates caudal to the nasal septum, especially the lower airways
- Nasal discharge from the guttural pouches can be unilateral or bilateral depending on the volume of discharge
- Malodorous discharge is associated with anaerobic infections, foreign bodies, necrotic bone, and tooth root abscesses
- Respiratory—lower tract, consisting of alveoli, bronchioles, bronchi, and trachea; upper tract, consisting of nasopharynx, guttural pouches, larynx, turbinates, conchae, nasal passages, paranasal sinuses, and false nostrils
- Gastrointestinal—oropharynx and esophagus
- Foals and young horses or any immunocompromised animal more prone to infections
- Neonates with milk in the discharge may have cleft palate or selenium deficiency, and resulting aspiration pneumonia
- Older horses—tooth infections, sinusitis, neoplasia
- Any age horse can have trauma, or bacterial infection
- Historical information should include whether nasal discharge is continuous or intermittent, spontaneous or occurs only during exercise or while eating, copious or scant, unilateral or bilateral, and whether discharge is accompanied by other signs such as coughing, fever, reluctance to eat, dyspnea, respiratory noise, odor, or exercise intolerance
- Response to previous treatments and management changes should also be documented
- Exposure to other animals with disease may indicate an infectious process
- Seasonal correlation with worsening or alleviation may indicate allergic disease
- Facial swelling or bony remodeling is indicative of a chronic sinus problem, trauma, or tooth disease
- Ongoing discharge or dried material at nares
- Normal or decreased airflow at the nares with airway compromise
- Fever—consistent with infectious agent
- Chronic dyspnea, tachypnea, nostril flaring, increased abdominal respiratory effort, and “heaves line” are suggestive of SEA (heaves, recurrent airway obstruction)
- Lymphadenopathy with swelling and inflammation of retropharyngeal or submandibular lymph nodes with Streptococcus equi ssp. equi (strangles) or, less commonly, S. equi ssp. zooepidemicus infection
- Guttural pouch distention with empyema, tympany, or chondroids
- Dull areas on percussion of paranasal sinuses indicate exudate or cystic structure
- Evidence of dental disease associated with sinusitis
- Foul odor occurs with tooth root infection, bony necrosis (i.e. neoplasia), foreign body, Gram-negative or anaerobic lung abscessation, or necrotizing pneumonia
- Abnormal lung sounds consistent with pneumonia, pleuropneumonia, or SEA; may be exacerbated or elicited with use of a rebreathing bag
- Percussion of lung field—dull areas are indicative of pleural fluid, abscess, or consolidated lung
- Auscultation of fluid in trachea with exudate in pneumonia or SEA
- Dysphagia with esophageal obstruction, guttural pouch disease (resulting in neuropathy), or episodes of HYPP
- Milk in discharge with cleft palate in neonates, severe depression, botulism, HYPP or nutritional myopathy
- Depression—severe illness with pneumonia or pleuropneumonia
- Plaque of edema between the front legs in cases of pleuropneumonia
- Common causes are bacterial infections, bacterial infections following initial viral infections, and SEA
- Bacterial infections—S. equi lymphadenitis, guttural pouch empyema, sinusitis, lung abscessation, pneumonia, and pleuropneumonia
- Mycotic rhinitis, guttural pouch infection, or sinusitis
- Foreign bodies or trauma with subsequent inflammation/infection
- Esophageal obstruction or pharyngeal dysfunction resulting in dysphagia and aspiration
- Exposure to animals infected with upper respiratory virus or strangles. Lack of vaccination against respiratory pathogens
- Viral infections—influenza and equine herpesvirus especially with young animals and congregated housing
- Poor deworming history—migrating ascarids predispose foals and yearlings to secondary bacterial pneumonia
- Immunodeficiency and immunosuppression—FTPI, severe combined immunodeficiency syndrome, PPID, and steroid therapy
- Environmental—indoors, dust, molds, air pollutants, and smoke inhalation
- Transport—subsequent pleuropneumonia
- Dental disease
- Dysphagia and aspiration associated with esophageal choke, cranial nerve damage, guttural pouch disease (mycosis), botulism, HYPP episodes affecting pharyngeal muscles
- Selenium deficiency in foals resulting in dysphagia and aspiration
DIAGNOSIS
TREATMENT
MEDICATIONS
FOLLOW-UP
MISCELLANEOUS