title: Prevalence of Streptococcus dysgalactiae subsp. equisimilis and S. equi subsp. zooepidemicus in a sample of healthy dogs, cats and horses.
abstract: OBJECTIVE
  To estimate the prevalence of β-haemolytic Lancefield group C streptococci in healthy dogs, cats and horses; to determine if frequent contact with horses was associated with isolation of these species from dogs and cats; and to characterise recovered S. equi subsp. zooepidemicus isolates by multilocus sequence typing.
  
  
  METHODS
  Oropharyngeal swabs were collected from 197 dogs and 72 cats, and nasopharyngeal swabs from 93 horses. Sampling was carried out at the Massey University Veterinary Teaching Hospital, on sheep and beef farms or on premises where horses were present. All animals were healthy and were categorised as Urban dogs and cats (minimal contact with horses or farm livestock), Farm dogs (minimal contact with horses) and Stable dogs and cats (frequent contact with horses). Swabs were cultured for β-haemolytic Streptococcus spp. and Lancefield group C streptococcal subspecies were confirmed by phenotypic and molecular techniques.
  
  
  RESULTS
  Of the 197 dogs sampled, 21 (10.7 (95% CI= 4.0-25.4)%) tested positive for S. dysgalactiae subsp. equisimilis and 4 (2.0 (95% CI=0.7-5.5)%) tested positive for S. equi subsp. zooepidemicus. All these isolates, except for one S. dysgalactiae subsp. equisimilis isolate in an Urban dog, were from Stable dogs. S. dysgalactiae subsp. equisimilis was isolated from one Stable cat. Of the 93 horses, 22 (23.7 (95% CI=12.3-40.6)%) and 6 (6.5 (95% CI=2.8-14.1)%) had confirmed S. dysgalactiae subsp. equisimilis and S. equi subsp. zooepidemicus isolation respectively. Isolation of S. dysgalactiae subsp. equisimilis from dogs was associated with frequent contact with horses (OR=9.8 (95% CI=2.6-72.8)). Three different multilocus sequence type profiles of S. equi subsp. zooepidemicus that have not been previously reported in dogs were recovered.
  
  
  CONCLUSIONS
  Subclinical infection or colonisation by S. equi subsp. zooepidemicus and S. dysgalactiae subsp. equisimilis occurs in dogs and further research on inter-species transmission and the pathogenic potential of these Lancefield group C streptococci is needed. Complete speciation of β-haemolytic streptococci should be recommended in clinical cases and the possible exposure to horses and their environment should be considered in epidemiological investigations.
authors.affiliation: a Massey University Veterinary Teaching Hospital, Institute of Veterinary, Animal and Biomedical Sciences , Massey University , Palmerston North , New Zealand.
authors.forename: E
authors.initials: E
authors.lastname: Acke
authors.forename: A C
authors.initials: AC
authors.lastname: Midwinter
authors.forename: K
authors.initials: K
authors.lastname: Lawrence
authors.forename: S J G
authors.initials: SJ
authors.lastname: Gordon
authors.forename: S
authors.initials: S
authors.lastname: Moore
authors.forename: I
authors.initials: I
authors.lastname: Rasiah
authors.forename: K
authors.initials: K
authors.lastname: Steward
authors.forename: N
authors.initials: N
authors.lastname: French
authors.forename: A
authors.initials: A
authors.lastname: Waller
mesh_terms: D000818:Animals; D002353:Carrier State; D002415:Cats / Q000382:microbiology*; D004285:Dogs / Q000382:microbiology*; D006736:Horses / Q000382:microbiology*; D009960:Oropharynx / Q000382:microbiology; D013291:Streptococcus / Q000145:classification / Q000302:isolation & purification*
keywords: S. equi subsp. zooepidemicus; Streptococcus dysgalactiae subsp. equisimilis; dog; epidemiology; horse; prevalence