strangles

Question 1

what pathogen causes strangles?
why is strangles very contagious?

Answer 1

Streptococcus equi equi

◦ Carrier state 10% of horses that are infected
◦ Interrmittent shedding
◦ Environmental persistence
◦ Fomites, contact,

Question 2

what are the clinical signs of strangles?

Answer 2

• sudden pyrexia (48h pre-shedding)
• mucopurulent nasal discharge
• Retropharnygeal and Submandibular LN abscessation

Question 3

what are the clinical signsof pharyngitis?

Answer 3

• Nasal discharge
• Dysphagia
• Cough
• Laryngeal-associated pain
• Extended head

Question 4

when does Ln abscessation occur with strangles? what LN are affected, what are the consequences of this?

Answer 4

• Abscessation 3-14 days after infection
  ◦ Retropharyngeal - most commonly affected
  ◦ Submandibular
  ◦ Parotid
  ◦ Cranial cervical - least commonly affected
• RPLNs Commonly rupture into GPs
• causes Guttural pouch empyema (puss)
• abscess can also drain externaly

Question 5

what are the complication of strangles?

Answer 5

• pneumonia
• distant abscesses affecting other body systems - lymphatic or haematogenous spread
• sever dyspnea
• immune mediated myositis and myocarditis
• Purpura haemorrhagica - blood vessels to swell and leak, resulting in red spots and swelling in the limbs and head
  ◦ type III hypersensitivity reaction that occurs weeks after strangles infection - non-contagious

Question 6

how is stangles diagnosed with acute disease?

Answer 6

• History (onset, management, exposure, travel, new horses?)
  Clinical signs (variable, non-specific) but vital
• Endoscopy, ultrasonography, radiography.
• Pathogen identification
  ◦ Culture (34-45% sensitivity) - lots of false negatives
  ◦ qPCR of nasopharyngeal lavage - optimal test
  ‣ Followed by NP swabbing & then nasal swabbing - less accurate

nasal swab works while the horse has clinical signs, GP and serology are not accurate during acute infection

Question 7

how do you diagnose persistent infection of stangles?

Answer 7

• qPCR of endoscopic guttural pouch lavage - best!
• qPCR 3xNP lavage + qPCR 1xGP lavage (alternatively) (NP lavage needs to be done 7 days apart)

Question 8

what are the two types of serology test for strangles and what are they both used for?

Answer 8

SeM-based ELISA
* helps to diagnose metastatic abscess and to identify animals predisposed to purpura hemorrhagica
* some cross-reactivity with a similar protein in streptococcus equi subspecies zooepidemics, causing a moderately high rate of false positives.

• Dual-target ELISA to ID exposed animals in the aftermath of an outbreak - optimal
  ◦ Identify exposed animals for GP lavage PCR testing

Question 9

what is the treatment of strangles and what is the treatment of the complications of strangles?

Answer 9

• NSAIDs - for the pyrexia, inflammation, pain
• Soft, palatable, calorific diet.
• Abscess management (hot packing, surgical drainage & lavage)
• Isolation
• Nursing care

treatment of complications:
* GP lavage (coiled or foley catheter)
* Antibiotics
* Abscess drainage & lavage

Question 10

when are antibiotics given for strangles?

Answer 10

• Persistent infection (benzylpenicillin reverse thermodynamic gel) - gel that solidifies when temperature increases
• Horses w/severe dyspnoea,
• Dysphagia
• persistent fever