Lumbosacral MRI findings in two dogs diagnosed with a Neospora caninum infection

A 5-month-old, male, entire labrador retriever (case 1) and a 6-year-old, female, neutered greyhound (case 2) presented following chronic, progressive, non-painful paraparesis in both cases with L4-Cd and L4-S1 neurolocalisation respectively. Magnetic resonance imaging of the lumbosacral region revealed multifocal muscular changes in both cases with patchy T2-weighted and water-weighted T2-weighted Dixon hyperintensities, with moderate contrast enhancement throughout the gluteal and lumbar paraspinal muscles. Multifocal radiculoneuropathy in case 1 and meningomyelitis in case 2 were identified. Crucially, in case 1, the identification of abnormal muscles on magnetic resonance imaging allowed the diagnosis of neosporosis via polymerase chain reaction on targeted muscle biopsy when previously indirect fluorescent antibody test serology was inconclusive and polymerase chain reaction on lumbar cerebrospinal fluid was negative. These cases highlight the magnetic resonance imaging findings of canine lumbar neosporosis and offer an alternative route of diagnosis through targeted muscle biopsy.