8.2.2: Introduction to nasal discharge Flashcards
How do you localise where nasal discharge is coming from?
- Unilateral discharge = usually rostral to the nasal septum/ larynx (nasal passages and sinuses)
- Bilateral discharge = usually caudal to the nasal septum/ larynx (guttural pouch, pharynx, larynx, trachea, bronchi, and lungs - occasionally these can present as unilateral)
History to take into account with nasal discharge
- Age (consider if infectious disease likely)
- Use of horse, ownership
- Onset (sudden = likely infectious disease compared to insidious), duration, progression
- Contact with other horses / other horses affected (infectious?)
- Management (pasture of stabled, type of feed, bedding - consider asthma)
- Seasonality (consider asthma)
- Effect of exercise
- Previous/ concurrent disease
Upper airway diagnostic techniques
- Oral/ dental exam
- Head radiography
- Endoscopy (resting and exercising, sinoscopy)
- CT
- Haematology and biochemistry
- Infectious disease tests (culture, PCR, ELISA)
Lower airway diagnostic techniques
- Endoscopy
- Tracheal wash (culture and cytology)
- Bronchioalveolar lavage (culture and cytology)
- Ultrasonography
- Radiography
- Haematology and biochemistry
- Specific tests for infectious disease e.g. serology, ELISA
Clinical signs of respiratory disease and where these localise to
- Unilateral vs bilateral discharge (rostral vs caudal to larynx)
- Type of discharge (consider type of disease)
- Swelling, pain, LN enlargment -> URT
- Respiratory noise -> URT
- Cough (pharynx/ larynx or LRT)
- Exercise intolerance
- Appetite, demeanour
- RR and effort (LRT)
Also check for other clinical signs:
* Abortion and neuro disease (herpes)
* Peripheral oedema (Equine viral arteritis)
* Cranial nerve neuropathies (guttural pouch disease)
Clinical signs of upper airway disease
Unilateral or bilateral discharge
Localising signs to the head/ pharyngeal region
* Submandibular or retropharyngeal LN enlargment
* Guttural pouch swelling
* Draining tracts
* Dental abnormalities
* Respiratory noise
* ± cough
* ± systemic signs (strangles, neoplasia)
Clinical signs of lower airway disease
- Cough
- Increased RR
- Increased resp effort
- Increased resp noise on auscultation
- Stance and demeanour (pneumonia)
- Exercise intolerance
- ± systemic signs (herpes, EVA, pleuropneumonia, neoplasia)
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URT differential list: nasal passages
- Cleft palate
- Cysts
- Polyps
- Ethmoid haematoma
- Trauma
- Foreign body
- Fungal rhinitis
- Neoplasia
URT differential list: sinuses
- Primary and secondary (inc dental) bacterial sinusitis
- Cysts
- Neoplasia
- Ethmoid haematoma
- Trauma
- Fungal sinusitis
- Foreign body
URT differential list: guttural pouch
- Empyema
- Mycosis
- Tympany
- Trauma
- Neoplasia
URT differential list: pharynx/ larynx
- Pharyngitis
- URT bacterial or viral disease
- Arytenoid chondritis
- Foreign body
LRT differential list: lung disease
- Inflammatory conditions: asthma
- Infectious conditions: pneumonia, pleuropneumonia, equine influenza, equine herpes virus, equine viral arteritis, Dictyolcaulus arnfieldi
- Neoplasia
- Exercise-induced pulmonary haemorrhage (EIPH)
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Frontal sinus draiage
Guttural pouch tympany
Diagnostics used for URT
- Radiography
- (CT for dental disease, head lesions)
- Endoscopy
- Haematology and biochemisty
- Infectious disease tests
Pros and cons of radiography for imaging of URT
✅ Good for dental, sinus, and guttural pouch conditions (bony lesions and fluid lines)
❌ Not so good for soft tissues, lower airway disease
Pros and cons of endoscopy for imaging in respiratory disease
✅ Good for most URT and LRT lesions, visualising inside spaces, soft tissue, mucosal lesions
❌ Not so good for bony lesions, severe epistaxis (red out)
When are haematology and biochemistry useful in respiratory disease investigations?
✅ Useful for identifying infectious processes/ systemic involvement
* Do not use indiscriminantly in all cases; consider whether it would change you decisions and treatment
* Haematology, fibrinogen, serum amyloid A most useful
What infectious diseases might you test for in investigation of respiratory disease and how will you do this?
- Strangles - options include nasal swab, guttural pouch lavage, can also do serology
- Equine influenza - nasal swab, serology
- Equine herpes viurs - nasal swab, serology
- Equine viral arteritis - serology, tissue samples
What diagnostics could you use for detecting disease of the LRT?
- Tracheal wash
- BAL
- Ultrasonography
- Thoracic radiography
- Can also aspirate of pleural fluid
- (CT for head lesions)
Pros and cons of ultrasonography for investigation of LRT disease
✅ Good for pleural disease, diseases affecting periphery/ surface of lung
❌ Not so good for diseases deeper within lung tissue, due to acoustic shadowing for air
Pros and cons of thoracic radiography of LRT disease
✅ Good for large masses, fluid line, foals/ small equids
❌ Not so good for most diseases and larger horses
Pros and cons of CT for LRT disease
✅ Great for difficult head lesions/ dental disease
❌ Expensive, only available in some referral hospitals
When could you use aspiration of pleural fluid to investigate LRT disease?
- Use in cases where there are pleural fluid lines
- Use in cases with neoplasia e.g. melanoma
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