Retrospective evaluation of 103 cases of septic arthritis in dogs.

OBJECTIVE: This study examines inciting causes, diagnosis, treatment and risk factors for the recurrence and outcome of septic arthritis (SA) in dogs. STUDY DESIGN: Medical records spanning 17 years from five referral hospitals were surveyed for presumptive and confirmed cases of SA. RESULTS: SA was identified in 103 cases. Spontaneous septic SA was the most common inciting cause. The most commonly affected joints were the stifle (40%) and elbow (24%). Pre-existing osteoarthritis (OA) was present in 63% of septic joints and was associated with recurrence (p = 0.03). Treatment with antibiotics prior to presentation was associated with a negative synovial fluid culture (p = 0.014). A successful outcome was associated with early treatment (p = 0.001) and SA due to direct penetration (p = 0.04) or spontaneous cause (p = 0.003). Recurrence was more likely in dogs with unsuccessful outcomes (p = 0.004) and bodyweights >30 kg (p = 0.009). CLINICAL SIGNIFICANCE: SA should be considered as a differential diagnosis in large breed dogs with pre-existing OA presenting with either an acute or chronic monoarthropathy. In the majority of cases, a successful outcome was achieved regardless of treatment type. Recurrence rates were low, but associated with pre-existing OA and higher bodyweight. Although treatment should be implemented as soon as possible to maximise outcome success, synovial fluid samples should ideally be obtained before empiric antibiotic administration.

A feasibility study investigating the utility of a point-of-care rapid immunoassay for detecting septic peritoneal effusion in dogs.

OBJECTIVE: To determine the sensitivity (SN), specificity (SP), positive predictive value (PPV), negative predictive value (NPV), and accuracy of a point-of-care urine bacterial rapid immunoassay (RIA) for a diagnosis of septic peritonitis, compared to more traditional diagnostic tools, such as cytology and bacterial culture. DESIGN: Prospective, cross-sectional feasibility study conducted from October 2016 to June 2017. SETTING: Four locations within a private practice referral hospital. ANIMALS: Sixty-four dogs with peritoneal effusion of any etiology were enrolled. Four dogs were excluded due to absent RIA or bacterial culture results. Two additional dogs were excluded because of an inability to definitively classify them as having septic peritonitis. INTERVENTIONS: Abdominocentesis was performed to obtain peritoneal effusion samples for aerobic and anaerobic bacterial culture, cytology, and RIA. Cytological slides were evaluated by a clinical pathologist following enrollment. MEASUREMENTS AND MAIN RESULTS: Fifty-eight dogs were included in the study, 8 of which were classified as having septic peritonitis. Compared to final diagnosis of septic peritonitis, RIA had a low PPV (36.8%) but good NPV (97.4%) and was 77.5% accurate. SN of RIA (87.5%) to diagnose septic peritonitis was similar to cytology (85.7%) and bacterial culture (87.5%); however, SP was lower (76%, 100%, and 98%, respectively). Cytology had the best overall predictive values and accuracy for diagnosing septic peritonitis (PPV 100%, NPV 97.9%, and accuracy 98%) compared to RIA and bacterial culture. CONCLUSIONS: RIA testing was similarly sensitive in identifying septic peritonitis compared to cytology and bacterial culture but was not very specific or accurate. As a stand-alone test, RIA commonly had false-positive test results, making it unreliable in identifying septic peritonitis. Cytology was the most accurate diagnostic test and had no false-positive results. Further investigation with a larger sample size and prevalence of septic peritonitis may prove beneficial.