Retrospective analysis of the effects of Blastomyces antigen concentration in urine and radiographic findings on survival in dogs with blastomycosis

Abstract Background The Blastomyces antigen concentration in urine (BACU) test is used to diagnose blastomycosis and monitor treatment in dogs. It is unknown if a higher BACU is associated with shorter survival. Objectives To determine if the magnitude of BACU before treatment is associated with survival in dogs with blastomycosis. Animals Fifty‐two dogs with blastomycosis. Methods Retrospective case review. BACU, radiographic lung severity (RLS) score (0‐4 scale), and survival time up to 1 year after diagnosis were obtained through medical record review of dogs with Blastomyces dermatitidis. Results The overall survival was: discharge, 87%; 1 week, 85%; 2 months, 74%; and 6 months, 69%. BACU correlated with RLS score (rs = 0.33, P = .02). BACU and RLS scores were lower in survivors to 2 months than nonsurvivors (average BACU difference of 2.5 ng/mL, 95% confidence interval [CI]: 0.2‐4.8 ng/mL, P = .04; median RLS difference of 2; range, 0‐4, P = .02). Dogs with BACU <5 ng/mL and dogs with mild (0‐1) RLS scores had a greater proportion surviving than those with BACU >5 ng/mL (P = .03) and dogs with severe (3‐4) RLS scores (P = .04). All dogs with a BACU <5 ng/mL or mild RLS score were alive at last follow‐up (median, 365 days; range, 44‐365 days). In all, 68.1% of other dogs survived to 2 months (95% CI, 54.8%‐84.8%). Conclusions and Clinical Importance Dogs with lower BACU and RLS scores have improved survival; however, it is unclear what specific cutoffs should be used for prognosis.