Early detection of septic arthritis caused by Streptococcus dysgalactiae subspecies equisimilis in a dog – a case report

In this report, a seven-year-old English Pointer male with Streptococcus dysgalactiae subsp. equisimilis arthritis joint infection is presented. The dog was referred to the Internal Medicine Department Policlinics with the symptoms of anorexia, weakness, swollen joints and ulcerative wounds on testes. On physical examination, the dog was depressed and manifesting discomfort during manipulation of the fore and hind legs’ joints. There were palpable effusions of the right carpal, elbow, and tibiotarsal joints. Haematological and serum biochemical analyses showed mild anaemia, moderate thrombocytopaenia, and elevated alanine aminotransferase. As soon as the synovial fluid aspirates were obtained aseptically from the right elbow, radiocarpal, and tibiotarsal joints, they were sent to bacteriological examination. Symptomatic and supportive treatment was initiated immediately. Empirical enrofloxacin therapy was initially started. Bacteria which were cultivated from the synovial fluid aspirates specimen were identified as S. equisimilis. The isolate was found to be resistant to enrofloxacin and susceptible to amoxycillin/ clavulanic acid. According to the results of the antimicrobial susceptibility tests, enrofloxacin therapy was terminated and amoxycillin/clavulanic acid therapy was immediately started lasting for four weeks. The dog was treated successfully. To our knowledge, Streptococcus dysgalactiae subsp. equisimilis was isolated from the synovial fluid from a dog for the first time in Turkey, as it is rarely seen in dogs. Streptococcus spp., arthritis, swollen joint, antimicrobial susceptibility Infectious arthritis is a common problem usually caused by bacterial agents that affect various species including humans, horses, and dogs. Septic arthritis which may cause pain, swelling, and lameness, is usually a monoarthropathy in dogs. Several different bacteria species, especially Staphylococcus intermedius, S. aureus and β-haemolytic streptococci have been isolated from septic arthritis in dogs (Bennett and Taylor 1988; Clements et al. 2005). Lancefield group-C streptococci are a common cause of infection in animals but rarely detected in humans (Bradley et al. 1991). Streptococcus dysgalactiae subsp. equisimilis (S. equisimilis) is a large-colony type (> 0.5 mm) Lancefield group C-haemolytic streptococcus that can rarely cause septic arthritis (Ike 1990). Septic arthritis may be suspected on the basis of clinical presentation: typically severe lameness and thickened painful joint(s) with or without concurrent systemic signs such as pyrexia, anorexia, and depression (Fearnside and Preston 2002). Clinical findings and medical treatment A seven-year-old English Pointer male, weighing 15 kg, was referred to the Internal Medicine Department Clinics with anorexia, weakness, swollen joints (Plate VIII, Fig. 1) and ulcerative wounds on testes. The anamnesis included that the patient’s owner had left the dog with his friend for 15 days. The dog’s symptoms started to appear after that time and the dog’s food intake started to decrease day by day.