Compressive myelopathy in a free-ranging red brocket (Mazama americana) caused by a lumbar paraspinal abscess with accompanying spondylodiscitis

Abstract

Background: Spondylodiscitis is an inflammation that is characterized by the involvement of one and more intervertebral discs and adjacent vertebral bodies. The clinical manifestations of spondylodiscitis are non specific and vary with the site and extent of injury, however this kind of lesion is poorly known between free-ranging cervids. In this sense, the presente study aimed to describe the occurrence, clinical, radiographic and anatomopathological findings related to a lumbar abscess accompanied by spondylodiscitis in a free-ranging female red brocket (Mazama americana) from Eastern Brazilian Amazon. Case: An approximately five-month old, 3,7 kg, female red brocket (Mazama americana), was received at the Veterinary Hospital of the Federal Rural University of Amazônia, in the municipality of Belém, in the State of Pará (Northern Brazil) for clinical care. The animal was rescued from the wild by the Brazilian Institute of Environment and Renewable Natural and presented lethargy, pelvic limb paralysis with proprioceptive deficits. The clinical signs observed suggested a spinal cord injury in the thoracolumbar region and the animal was sent to radiographic examination and myelography performed on the ventrodorsal and lateral projections of the vertebrae and spinal cord. The hemogram revealed anemia (8.74 × 106 cells/mm3) and leukocytosis (29.65 × 103cells/mm3) with neutrophilia (95%) and lymphopenia. The simple radiographic examination demonstrated no alteration, but the myelography showed an interruption of the contrast column at the L2 level. Considering the results in the laboratorial exams and advanced clinical state of debility, it was it was decided to euthanize the animal and subsequent necropsy. Macroscopically, a paravertebral abscess and spondylodiscitis were observed at L2 vertebra position, which resulted in compressive myelopathy. The histopathologic examination revealed an osteomyelitic process, chronic inflammation in the conjunctival fascia in one of the margins of the dura mater, and skeletal muscle abscesses. The presumptive diagnosis of spondylodiscitis was confirmed by the anatomopathological evaluation. Discussion: Spondylodiscitis and paravertebral abscesses have been widely described in domestic species, such as cattle, dogs, cats, horses, and, especially, pigs, however, reports of these diseases in wild species are still scarce, and the clinical manifestations seem to vary according to the specificity of the lesioned area and the severity of the lesion. The pathogenesis of the process in domestic ruminants may be related to relative blood stasis conditions within the vessels of the vertebral bodies, which are associated with hematogenous spread of pathogens and the occurrence of vertebral osteomyelitis in bovine neonates appears to be associated with deficiencies in passive immunity. Lumbar abscesses may be associated with lung abscesses and/or abscesses at other sites, and umbilical infections are an important route for the spread of hematogenous pathogens that can lead to discospondylitis in ruminants, however in this case, no umbilical lesions and internal organs abscesses that could be the primary source of infection were identified. To date, no previous study have reported this kind of lesion in Mazama americana. Therefore, this disease should be included on the list of differential diagnoses for neurologic changes in wild ruminants.