Atypical magnetic resonance imaging features and resolution following meglumine antimoniate therapy in a dog with Leishmania infantum infection

A 5-year-old, female, mixed-breed dog, undergoing therapy for leishmaniasis with allopurinol (10 mg/kg, twice daily) and marbofloxacin (2 mg/kg, daily), presented with hyperthermia and thoracolumbar pain. Thoracolumbar magnetic resonance imaging revealed paravertebral multifocal myopathy and polyostotic vertebral lesions; the latter was not identified with computed tomography. Based on clinical signs, laboratory findings and imaging results, a relapse of leishmaniasis was diagnosed. Treatment with oral allopurinol (10 mg/kg, twice daily), intramuscular meglumine antimoniate (10 mg/kg, daily) and oral prednisolone (1 mg/kg, daily) was initiated. After 4 days, hyperthermia and thoracolumbar pain were resolved. Six months later, the dog showed complete recovery, and follow-up magnetic resonance imaging revealed almost complete resolution of vertebral and muscular lesions. Bone marrow polymerase chain reaction for Leishmania infantum was negative, and although the antibody titer remained above the reference range, it decreased. This case represents the first instance of presumptive magnetic resonance imaging vertebral lesions not detected at computed tomography examination in a dog with leishmaniasis.