Caused by Streptococcus equi subsp. equi
- Epidemiology
- Strangles is a highly infectious disease of horses caused by Streptococcus equi subsp. equi
- upper respiratory tract disease of horses with fever and abscessation of regional lymph nodes
- Cause rhinitis, pharyngitis, lymphadenitis and myositis
- Outbreaks in groups of young horses
- Transmitted via purulent exudate discharging from upper respiratory tract or from lymph nodes
- Chronic, carrier state can occur with bacteria im the guttural pouch
- A mild, atypical form can occur
- S. equi shed for 4 weeks beyond clinical resolution
- Clinical signs
- Incubation period 3 to 6 days
- Fever, depression, anorexia
- Purulent nasal discharge
- Swollen, painful regional lymph nodes, especially submandibular
- Abscessation and rupture of lymph nodes
- Guttural pouch empyema
- 100% morbidity; 5% mortality
- Death can occur from pneumonia, breathing difficulties from swollen lymph nodes or purpura haemorrhagica(an immune-mediated disease)
- Bastard strangle may occasionally occur, with abscessaation in many organs of the body
- S. equi may be involved in cutaneous lesions
- Diagnosis
- Clinical signs and history
- Mucoid colonies with beta-haemolysis
- Sugar fermentation allows differentiation of S. equi from S. zooepidemicus and S. equisimilis
- PCR to detect asymptomatic carriers
- Treatment and control
- Penicillin administration to in-contact animals
- Isolation of affected animals
- Quarantne in-coming animals
- Avoid overcrowding and mixing different age groups
- Disinfection of equipment
- Gross pathology
- Initial bilateral nasal discharge, serous becoming purulent
- Catarrhal conjunctivitis may be present
- Less frequently, complications can occur as follows :
- Purulent inflammation may extent to guttural pouches or lungs, sinusitis
- Bacteraemia with metastatic abscesses - most often to the mesenteric and mediastinal lymph nodes, less frequently, other organs such as liver, kidney and brain can be involved - Bastard strangles
- Retropharyngeal abscesses can rupture onto the skin of neck or into the guttural pouch resulting in guttural pouch empyema or chondroid formation - carrier state
- Purpura haemorrhagica: an acute vasculitis causing urticaria and extensive oedema of ventrum, head and distal limbs
- Laryngeal hemiplegia due to enlarged retropharyngeal lymph nodes
- Compression of cranial nerves
- Interview with Professors Josh Slater and Ken Smith providing an interesting insight into the pathogenesis, prevalence and possible prevention of Streptococcus equi infections in horses - listen to Strangles podcast