8.2.2: Strangles Flashcards
Causative agent of strangles
Strep equi var equi
How is strangles transmitted?
- Fomites
- Direct contact
- Contaminated surfaces etc.
Clinical signs of strangles
- Sudden pyrexia 48hrs pre-shedding -> important in management of outbreaks
- Mucopurulent nasal discharge
- Retropharyngeal and submandibular LN abscessation
- Pharyngitis: nasal discharge, dysphagia, cough, laryngeal-associated pain, extended head position
When does lymph node abscessation happen in strangles and which lymph nodes are most commonly affected?
Occurs 3-14 days after infection
Most common LNs:
1. Retropharyngeal - these commonly rupture into the guttural pouches
2. Submandibular
3. Parotid
4. Cranial cervical
Moderate lymphoid hyperplasia (seen with strangles)
Guttural pouch empyema
The retropharyngeal lymph nodes rupture into the guttural pouches, filling the pouches with mucopurulent fluid.
Complications of strangles
- Pneumonia: bronchopleural fistula ends up leading to pneumothorax
- Distant abscesses due to lymphatic or haematogenous spread
- Development of severe dyspnoea -> may require tracheostomy
- Uncommon: purpura haemorrhagica, immune-mediated myositis, myocarditis are all possible
Purpura haemorrhagica
Type III hypersensitivity reaction that occurs weeks after infection
Diagnostic testing for acute strangles
- Optimal test = qPCR of nasopharyngeal lavage, followed by nasopharyngeal swabbing, then nasal swabbing
- Culture (34-45% sensitivity, very specific)
Diagnostic testing for persistent infection with strangles
- qPCR of endoscopic guttural pouch lavage x3 (7 days apart) = best
- Could do culture - this is very specific but has many false negatives.
How could you screen for animals that have been exposed to strangles?
- Dual target ELISA -> use this to screen for exposed animals
- This can help you select animals for guttural pouch lavage qPCR testing
When in a strangles outbreak should you begin to search for animals in the carrier state?
- Search for horses in carrier state 3-4 weeks after the last case in the outbreak was identified
- Any time before this is too early!
Treatment of strangles
- NSAIDs to manage pyrexia and pain
- Soft, palatable, calorific diet for anorexia/dysphagia
- Abscess management: hot packing, surgical drainage and lavage only once completely matured otherwise will result in incomplete drainage
- Isolation
- Nursing care
Treatment of the complications of strangles
- Guttural pouch lavage
- Antibiotics are controversial - not enough evidence to prove they prevent LN abscessation
- Treat persistently infected animals with benzylpenicillin reverse thermodynamic gel
- Give antibiotics to horses with severe dyspnoea, dysphagia, or persistent high fever - controversial
- Abscess drainage and lavage
- Other treatment according to specific complication
This is a latero-lateral view of the caudal part of the head. What is circled?
Guttural pouch
* Should be translucent
* Is in part radiopaque due to enlarged retropharyngeal LN bulging into the base of the guttural pouch
This is a latero-lateral view of the head. What abnormal findings are present?
Guttural pouch with chondroids
* Pus within the guttural pouches was not evacuated; remained, dessicated and formed chondroids
* These contain visible bacteria within them
* Bacteria can survive in here for a very long time
* Must remove chondroids to clear the infection and then treat
This is a latero-lateral view of the head. What abnormal findings are highlighted?
Visible fluid line within the guttural pouch
This is due to the presence of pus in the guttural pouch
