Microfilaruria of morphologically identified Dirofilaria repens and Brugia spp. in one cat and two dogs: Case series.

Microfilaruria is an uncommon parasitological finding in veterinary practice. This report describes three clinically distinct cases of microfilaruria in companion animals from Kerala, India, an endemic region for canine filariasis. Case 1 involved a dog with dual infection by morphologically identified Dirofilaria repens and Brugia spp., associated with hemorrhagic cystitis and hypermicrofilaremia. Case 2 involved a diabetic dog with E. coli urinary tract infection, in which microfilariae were detected in the urine sediment, likely due to glycosuria-induced epithelial compromise. This represents the first documented case of microfilaruria in a dog with concurrent diabetes mellitus. Case 3 documented the first reported occurrence of microfilaruria due to D. repens in a cat, which was likely triggered by trauma-induced urethral obstruction. All cases were managed with targeted therapy based on the primary diagnosis, combining anthelmintics, antibiotics, supportive care, and metabolic regulation. These cases suggest that microfilaruria may occur via various mechanisms, including inflammation-induced uroepithelial disruption, glomerular leakage, or local trauma. Molecular confirmation (e.g., PCR) was not performed; hence, definitive differentiation between D. repens and D. asiatica was challenging and represents a limitation of this study. The paper emphasizes the critical importance of routine, thorough urine sediment examination, even in atypical species like cats, and in animals with concurrent systemic or metabolic disorders. Early recognition of such unusual presentations may aid in timely intervention and broaden our understanding of filarial infections in veterinary clinical practice.