Strangles in Horses Flashcards
strangles - which bacteria causes it
Streptococcus equi subspecies equi
Strep. equi equi
gram positive
Not a normal inhabitant of URT
Does not require prior viral infection for colonisation
Highly infectious, particularly weanlings and yearlings
Equine specific
epidemiology
Infection primarily 1-5 yo Foals born from immune mares resistant for 3 months Morbidity 100% Mortality up to 10% with appropriate therapy 20% complication rate Immunity not lifelong 75% still immune after 3-4 years transmission by direct contact
pathogenesis
Incubation period 2 – 6 days, Recover over 2-3 weeks
Nasal shedding for 3-6 weeks after disease
31% ofhorses become carriers
Incomplete clearance of pus from GP
3 main clinical presentations
Classic acute disease
Atypical strangles
Complications
Classic Acute Disease - Clinical Signs
Fever, depression, inappetence
Abscessation of mandibular, parotid or retropharyngeal lymph nodes, rupture after 7-10 days
Dyspnoea and dysphagia if abscesses compress larynx or
interferes with cranial nerve to pharynx
Mucoid to purulent nasal discharge
Cough
Atypical Strangles - Clinical signs
Mild inflammation of URT Slight nasal discharge Cough Fever Self limiting lymphadenopathy - dependent on bacterial strain plus immunity + genotype of the horses
Complications - Clinical Signs
Internal abscessation Purpura hemorrhagica Anemia Guttural pouch empyema and chondroids Retropharyngeal abscessation Laryngeal hemiplegia Horner's syndrome CNS abscess Endocarditis or myocarditis Agalactia Tracheal compression due to cranial mediastinal LN abscess Suppurative bronchopneumonia ie LRT signs Myopathies
Internal abscessation
Intermittent colic PUO Anorexia Depression Weight loss Depends on site of abscess
Purpura hemorrhagica
generalized vasculitis caused by Type III hypersensitivity reaction
1-2% of infected horses
Thrombosis of small arteries can occur
Skin and muscle necrosis may result
Ventral edema, body swelling and petechial haemorrhages on mucus membranes
Death due to pneumonia, cardiac arrhythmia, renal failure, GI disorders
Diagnosis
Clinical signs
Leucocytosis, hyperfibringenaemia
Isolation (culture) or detection (PCR) of S. equi from LN, nasopharyngeal swab, GP lavage fluid
Culture of 3x n/ph swabs
Treatment - horses exposed to strangles
Treat with penicillin until isolated from infected horses
Will not become immune
Treatment - horses with early clinical signs
Penicillin
May inhibit natural immunity so may contract the disease again with continued exposure
General nursing, anti-pyretics, soft food
Treatment - horses with LN abscesses
Poulticing and drainage of abscesses
Antibiotics may prolong resolution of the abscess
General nursing, anti-pyretics, soft food
Treatment - with abdominal abscesses
long term antibiotics (usually penicillin or trimethoprim sulfa/rifampin) for up to 6 weeks)
