Transcutaneous Cervical Vagus Nerve Stimulation Induces Changes in the Electroencephalogram and Heart Rate Variability of Healthy Dogs, a Pilot Study.

Transcutaneous cervical vagus nerve stimulation (tcVNS) has been used to treat epilepsy in people and dogs. Objective electroencephalographic (EEG) and heart rate variability (HRV) data associated with tcVNS have been reported in people. The question remained whether EEG and electrocardiography (ECG) would detect changes in brain activity and HRV, respectively, after tcVNS in dogs. Simultaneous EEG and Holter recordings, from 6 client-owned healthy dogs were compared for differences pre- and post- tcVNS in frequency band power analysis (EEG) and HRV. The feasibility and tolerance of the patients to the tcVNS were also noted. In a general linear mixed model, the average power per channel per frequency band was found to be significantly different pre- and post-stimulation in the theta (p = 0.02) and alpha bands (p = 0.04). The pooled power spectral analysis detected a significant decrease in the alpha (p < 0.01), theta (p = 0.01) and beta (p = 0.035) frequencies post-stimulation. No significant interaction was observed between dog, attitude, and stimulation in the multivariate model, neither within the same dog nor between individuals. There was a significant increase in the HRV measured by the standard deviation of the inter-beat (SDNN) index (p < 0.01) and a decrease in mean heart rate (p < 0.01) after tcVNS. The tcVNS was found to be well-tolerated. The results of this pilot study suggest that EEG and ECG can detect changes in brain activity and HRV associated with tcVNS in healthy dogs. Larger randomized controlled studies are required to confirm the results of this study and to assess tcVNS potential therapeutic value.

Primary hyperlipidemia with associated ischemic strokes in a West Highland white terrier dog.

A 3-year-old spayed female, West Highland white terrier dog was evaluated because of a 4-month history of recurrent brain clinical signs. Magnetic resonance imaging (MRI) revealed multifocal brain lesions consistent with ischemic injuries. Blood analysis was unremarkable aside from severe hypertriglyceridemia and hypercholesterolemia with no underlying cause, suggesting primary hyperlipidemia. The patient was treated for hyperlipidemia and started on a low-fat diet and omega-3 supplementation. Clinical signs resolved over the following 12 months along with improvement in lipidemia. This represents the first reported case of MRI findings suggestive of multiple cerebrovascular injuries associated with primary hyperlipidemia in a dog, and the first primary hyperlipidemia reported in a West Highland white terrier dog.

Hyperlipidémie primaire associée à des accidents vasculaires cérébraux ischémiques chez un chien terrier West Highland white. Une femelle stérilisée West Highland white âgée de 3 ans fut évaluée à cause d'une histoire de signes cliniques cérébraux récurrents d'une durée de 4 mois. Une imagerie par résonnance magnétique (RMI) révéla des lésions cérébrales multifocales compatibles avec des blessures ischémiques. Une analyse sanguine s'avéra peu concluante sauf pour une hypertriglycéridémie et une hypercholestérolémie sévère sans cause sous-jacente, suggérant une hyperlipidémie primaire. Le patient fut traité pour l'hyperlipidémie et débuta une diète faible en gras et une supplémentation en oméga-3. Les signes cliniques se sont résolus dans les 12 mois suivants avec une amélioration de la lipidémie. Ceci représente le premier cas rapporté de trouvailles par MRI suggestives de lésions cérébro-vasculaires multiples associées avec une hyperlipidémie primaire chez un chien, et le premier cas d'hyperlipidémie primaire rapporté chez un terrier West Highland white.(Traduit par Dr Serge Messier).

Inner ear fluid-attenuated inversion recovery MRI signal intensity in dogs with vestibular disease.

The inner ear contains endolymph and perilymph. The second is comparable and in continuity with the cerebrospinal fluid (CSF) so it is expected to suppress in fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI) if normal. Even though inner ear FLAIR abnormalities have been extensively described in humans with inner ear disease, its diagnostic value in dogs is yet to be proven. The goal of this retrospective cohort study was to investigate the diagnostic utility of FLAIR MRI in dogs with vestibular disease. A review of medical records identified 101 dogs that had brain MRI performed because of vestibular signs. Based on the final diagnosis, patients were allocated to three groups: otitis media/interna, idiopathic vestibular disease, and central vestibular disease. Additionally, a control group (n = 73) included dogs with normal MRI and without vestibular signs. Inner ears were delineated using a region of interest, and signal intensity was measured in FLAIR and T2-weighted images. The percentages of suppression in FLAIR were calculated and compared between affected and unaffected sides of each individual and between groups using a general linear mixed model. Correlation between suppression and CSF cell count and protein concentration was assessed. Affected inner ears in dogs with otitis media/interna had decreased suppression in FLAIR compared to the unaffected side (P < .001), and all other groups (P < .01). No significant correlation was detected between CSF results and suppression. These results show the diagnostic value of FLAIR in otitis media/interna due to lack of suppression in the affected inner ear.