Background: Refractory epilepsy is a concern for many canines diagnosed with idiopathic epilepsy. In humans, refractory epilepsy is most often associated with temporal lobe epilepsy (TLE). In dogs, TLE pathology can go unnoticed on standard magnetic resonance imaging (MRI) examination. In recent years, many studies have described the occurrence of TLE in dogs and cats diagnosed through volumetric evaluation of the hippocampus. Nevertheless, this has been performed manually, which may reduce the diagnostic sensitivity of the method. Additionally, due to the challenges involved in the manual assessment in dogs, volumetric evaluation of the brain lobes has not yet been possible. In contrast, automated volumetry has long been used for the diagnosis of many neurological diseases in humans. The development of veterinary medicine and availability of brain atlases has now made it possible to introduce automated volumetry in to veterinary neurology as well. Thus, this study aimed to develop an automatic volumetry method, translate the outcomes into the assessment of temporal lobe volume in dogs with idiopathic epilepsy, and correlate the results with the electroencephalography (EEG) of epileptiform discharges (EDs). Results: An automated volumetry method was developed in this study, which allowed the evaluation of temporal lobe volumes of 31 dogs diagnosed with idiopathic epilepsy. The asymmetric ratio (AR) was then estimated and the results were correlated with the EEG EDs. Notably, 12/31 dogs had an AR greater than 6%. Among them, reduction in temporal lobe volume correlated with the side of the EEG EDs in seven cases. However, statistical analysis revealed no correlation between temporal lobe volume changes and ED location. There was a statistically significant difference in the AR between the group with a larger right ventricle and the group with symmetrical ventricles. Conclusions: Our results may influence the classification of idiopathic epilepsy in dogs. Additionally, the diagnosis of TLE in dogs based on MRI volumetry in correlation with EEG examination, especially for dogs with drug-resistant epilepsy, can significantly influence the development of new therapeutic options such as surgery.

Syringomyelia secondary to Chiari-like malformation (so-called CM-SM syndrome) is a common disorder in Cavalier King Charles Spaniels (CKCS) that is diagnosed using standard structural MRI, though imaging findings often do not correlate with the severity of clinical symptoms. Diffusion tensor imaging (DTI) is a technique that defines subtle microstructural changes in the course of many brain and spinal cord diseases, that are not visible on standard MRI. The aim of the study was to identify the correlation between the presence of clinical symptoms and DTI parameters, such as apparent diffusion coefficient (ADC) and fractional anisotropy (FA) within the spinal cord in the course of CM-SM. Study subjects included 18 dogs, CKCS with MRI-confirmed SM (SM group), and 12 CKCS dogs without SM (non-SM group). The SM group was divided into SM-symptomatic group (n = 8) and SM-asymptomatic group, n = 10). All dogs underwent same clinical and neurological assessment followed by MRI examination. All MRI studies were performed on a 1.5T MRI scanner. The MRI spine protocol included: transverse and sagittal T2-weighted images followed by DTI performed in the sagittal plane. The measurements of FA and ADC values were performed manually using the region of interest (ROI) method at the level of three intervertebral discs between C1 and C4. Notable differences in age and body weight were found. No significant differences in FA and ADC values between the SM and non-SM groups were found, but between non-SM, SM-asymptomatic and SM-symptomatic groups significant differences were found in ADC values in all three ROIs and in FA values in ROI-1 and ROI-3. SM-symptomatic dogs compared to non-SM, showed decreased FA value in ROI-1 and ROI-3 also increased ADC value in ROI-1, ROI-2 and ROI-3. SM-symptomatic dogs compared to SM-asymptomatic showed also decreased FA value in ROI-1 and ROI-3, and also increased ADC value in ROI-1, ROI-2 and ROI-3. The results suggest that the values of DTI parameters correlate with the severity of clinical symptoms in the course of CM-SM in animals. The use of DTI evaluation of CM-SM patients carries a potential value as a clinically relevant protocol for an objective assessment of the spinal cord.