Novel MRI and histopathological findings in a young Bullmastiff cross dog with mitochondrial fission encephalopathy

A 9-month-old male Bullmastiff cross dog was presented with a history of progressive proprioceptive ataxia and behavior changes. Neuroanatomical localization was multifocal with forebrain and vestibulo-cerebellum involvement. MRI identified moderate diffuse cerebral sulci widening, dilation of the ventricular system, and rounded, well-defined, bilaterally symmetrical T2W, FLAIR, and T2* hyperintense intra-axial lesions affecting the olivary nuclei. Histopathological examination was indicative of a primary mitochondrial disorder. This was confirmed following genetic analysis which identified mitochondrial fission encephalopathy with a homozygous frameshift variant in the MFF gene. This case report documents diagnostic imaging and histopathological findings not previously reported in dogs affected with mitochondrial fission encephalopathy, suggesting a different selective regional vulnerability of the neurons.

MRI and clinical findings in 133 dogs with recurrent deficits following intervertebral disc extrusion surgery

BACKGROUND

Recurrence of neurological signs following surgery for intervertebral disc herniation (IVDH) is reported, yet many cases lack MRI-confirmed diagnosis. This study describes the MRI and clinical findings in dogs presenting with recurrence of neurological signs following surgical treatment of IVDH.

METHODS

Medical records of dogs that underwent decompressive surgery for IVDH followed by a subsequent MRI within 12 months were retrospectively reviewed.

RESULTS

One hundred and thirty-three dogs were identified, all of which initially presented with intervertebral disc extrusion (IVDE). Of these, 109 (81.9%) had a recurrent IVDE, and 24 (18.1%) had an alternative diagnosis that included haemorrhage (n = 10), infection (n = 4), soft tissue encroachment (n = 3), myelomalacia (n = 3) or other (n = 4). Same-site IVDE recurrence or alternative diagnoses were significantly more likely to present within 10 days postoperatively. Thirty-nine percent of dogs presenting with 'early recurrence' had an alternative diagnosis. Type of surgery, fenestration, neurological grade or IVDE site was not significantly associated with the subsequent MRI diagnosis.

LIMITATIONS

Limitations include the retrospective study design, the exclusion of conservatively managed recurrences, the variable length of follow-up and differences in the clinicians' surgical experience.

CONCLUSION

The most common cause for the recurrence of neurological signs following decompressive spinal surgery was IVDE. Just over one-third of dogs presenting with early recurrence had an alternative diagnosis.