Streptococcus equi subsp. equi

Causes Strangles

• 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
  • Causes 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