Therapeutic Failure and Relapse of Babesia gibsoni Infection in a Working Dog

A 6.5-year-old male Labrador Retriever working dog diagnosed with canine babesiosis, unresponsive to conventional triple antibiotic therapy (doxycycline-clindamycin-metronidazole), presented with severe clinical signs including haematuria, jaundice, weakness, and recumbency. Hematobiochemical examination revealed abnormal blood parameters, and PCR analysis confirmed the presence of the Babesia gibsoni parasite. Due to suspected drug-resistant variants, treatment was shifted to buparvaquone and azithromycin (BA) for 20 days, resulting in clinical improvement and parasite clearance. However, relapses occurred on days 60 and 98 post-BA withdrawal, both resolved with oral doxycycline. At day 182, the dog exhibited mild exercise intolerance, prompting cardiac evaluation revealing borderline systolic function. This case underscores the need for alternative therapies for babesiosis unresponsive to standard treatment and emphasizes the importance of exploring cardiac implications in severe cases. Future research on potential resistant variants of B. gibsoni is crucial for a comprehensive understanding of treatment challenges in complicated forms of the infection.