Persistent pseudomembranous cystitis associated with Vagococcus lutrae in a setter dog: First clinical report.

Urinary tract infections (UTIs) are among the most common diseases in companion animals, but empirical antibiotic treatments without culture often lead to recurrence and resistance. Vagococcus species are rarely reported as pathogens in animals, and Vagococcus lutrae has not previously been described in dogs. We report the first case of V. lutrae-associated cystitis in a dog in Türkiye. An 8-year-old female English Setter developed persistent dysuria and hematuria after surgery for pelvic trauma. Despite multiple antibiotic treatments (enrofloxacin, ceftriaxone, ciprofloxacin, amoxicillin-clavulanic acid), no clinical improvement was observed. On presentation, hematology indicated leukocytosis with regenerative anemia, and ultrasonography revealed bladder wall thickening and intraluminal hyperechoic material consistent with cystitis. Urine obtained by cystocentesis appeared dark red, alkaline (pH 9), and contained struvite crystals and urothelial cells. Urine culture obtained by cystocentesis yielded a pure growth of Gram-positive cocci identified as V. lutrae using MALDI-TOF mass spectrometry. Antibiotic susceptibility testing showed resistance to commonly used antimicrobials, including amoxicillin, ceftriaxone, ciprofloxacin, doxycycline, and gentamicin, but susceptibility to daptomycin, vancomycin, and teicoplanin. Supportive therapy was initiated; however, the patient died on the third day of treatment. This case suggests the potential pathogenic relevance of V. lutrae in dogs and emphasizes the importance of culture and sensitivity testing in recurrent or treatment-resistant UTIs to guide appropriate antimicrobial therapy.