Disease of the equine head and neck 4 Flashcards
(53 cards)
What are the guttural pouches?
Air-filled, mucosa lined outpouchings of the auditory tubes connecting the nasopharynx to the middle ear
What is the possible function of the guttural pouches?
Possibly related to cooling of the blood before reaching the brain
Describe the features and bordering structures of the guttural pouches
- Paired: median septum (very thin)
- Approximately 350ml in volume
- Dorsally: base of skull & 1st cervical vertebra. Tympanic bulla & auditory meatus
- Medially: median septum, rectus capitus & longus capitis ventralis
muscles - Ventrally: Retropharyngeal lymph nodes. Nasopharynx
- Laterally: Parotid & mandibular salivary glands, Pterygoid muscles
How does each pouch connect to the nasopharynx?
- Via a funnel shaped
auditory tube - Orifice has a fibrocartilage flap = The otium / ostia
Which structure separates each guttural pouch into medial and lateral compartments?
Stylohyoid bone
Which arteries are associated with the guttural pouch?
Internal and external carotid arteries (ICA / ECA)
Describe the location and function of the Circle of Willis
Found at the base of the brain.
Ensures perfusion to the brain even if an artery is blocked – makes surgery to occlude the arteries in cases of guttural pouch mycosis more complex
Each guttural pouch is composed of?
A medial and lateral compartment
MEDIAL > lateral
2/3 versus 1/3
Clinical signs of guttural pouch disease include?
- Epistaxis
- Dysphagia
- Nasal discharge
- Dyspnoea
- External swelling
- Neurological signs
What are the key points to note in the clinical assessment of a horse with suspected disease of the guttural pouch?
- Epistaxis
- Trauma
- Nasal discharge
- Recent Strep equi var equi infection?
- Is emergency supportive
treatment required first? - Respiratory distress (tracheostomy?)
What is guttural pouch mycosis?
Fungal plague forms over artery
Most commonly the ICA but ECA / MA can occasionally be affected
What is the causative agent of guttural pouch mycosis?
Aspergillus spp
What are the main signs/concerns with guttural pouch mycosis?
- Relatively uncommon
- EPISTAXIS
- Potentially life threatening: fatal, uncontrolled haemorrhage
Must rule out guttural pouch mycosis in horses with epistaxis particularly if there are which features?
- Large volume of arterial haemorrhage from nares
- History of recent epistaxis (may be fatal after 2 recent episodes)
- No history of trauma / recent intense exercise
Describe the history of a horse with guttural pouch mycosis?
- Moderate to severe epistaxis
- May have had several mild episodes in the previous days / weeks
+/- dysphagia (lesions over nerves, can present without epistaxis)
What are the main clinical signs of guttural pouch mycosis?
Nasal discharge Epistaxis \+/- nerve dysfunction: - Dysphagia - Horners - Laryngeal paralysis
Name the differential diagnosis for URT epistaxis?
- Guttural pouch mycosis
- Head trauma
- Progressive ethmoid haematoma
- Sinus trauma
- Nasal passage trauma (iatrogenic)
- Foreign body
- Neoplasia
Name the differential diagnosis for LRT epistaxis?
- Exercise induced pulmonary haemorrhage
- Neoplasia
- Lower airway inflammation
Name the cardiac differential diagnosis for epistaxis?
- Atrial fibrillation
- Mitral insufficiency
How is guttural pouch mycosis diagnosed?
Endoscopy
What is seen when using endoscopy to diagnose guttural pouch mycosis?
Blood draining from ostium
- Usually unilateral but can be bilateral
• +/- DDSP or laryngeal paralysis
• +/- Pharyngeal collapse
• Diphtheritic membrane fungal plaque/blood clot overlying ICA/ECA
What care must be taken when using the endoscope in the case of a guttural pouch mycosis?
Care must be taken to avoid disrupting the clot and cause a fatal haemorrhage
Don’t enter GP with endoscope
Best to examine the guttural pouch at the surgical facility
Describe the Initial triage & management on the yard in an emergency guttural pouch mycosis case
Do not wait to act!
GPM ASSOCIATED WITH EPISTAXIS IS A TRUE EMERGENCY
- Assess Cardiovascular status: HR / PP / MM colour / mentation
- Must keep the horse calm
- Minimise the risk of dislodging the clot & restarting haemorrhage
- Do not administer fluids / perform endoscopy within the guttural pouch on the yard
- Immediate transportation to a surgical facility
+/- administer Acepromazine as an anxiolytic if necessary
Describe different surgical treatments for guttural pouch mycosis
- Surgical occlusion of the affected artery/arteries: must occlude cardiac & cerebral side
- Simple ligation of the ICA
- Balloon catheterisation / Coil embolization, Nitrol plugs
- Treat hypovolaemia: blood transfusion (during surgery)
