Vagus Nerve Stimulator Placement in Dogs: Surgical Implantation Technique, Complications, Long-Term Follow-Up, and Practical Considerations.

OBJECTIVE: To describe a modified implantation procedure of a vagus nerve stimulation (VNS) device in dogs and to report short- and long-term complications. STUDY DESIGN: Descriptive, experimental study. ANIMALS: Healthy, adult Beagle dogs (n = 10). METHODS: A VNS Therapy(®) System was implanted in the left cervical region of anesthetized dogs. During and within 48 hours after surgery, electrocardiography (ECG) and impedance testing of the system were performed. Dogs were monitored daily and the impedance of the system was determined regularly until VNS devices were surgically removed 3 years after implantation. RESULTS: The implantation procedure was successful in all dogs without intraoperative complications. ECG monitoring and impedance tests were within normal limits during and within 48 hours after surgery. Postoperative seroma formation was common (70%). One dog developed an irreversible Horner's syndrome leading to removal of the device 5 months after implantation. Another dog developed trauma-induced damage of the lead requiring surgical revision. The device could be safely removed in all dogs; however, electrodes were left in place to avoid nerve damage. At removal, the anchor tether was dislodged in 40% of dogs and the lead was twisted in 50% of dogs. CONCLUSION: Implantation of a VNS Therapy(®) System is safe and feasible in dogs; however, seroma formation, twisting of the lead, and dislodgement of the anchor tether were common. Practical improvements in the technique include stable device placement, use of a compression bandage, and exercise restriction. Regular evaluation of lead impedance is important, as altered values can indicate serious complications.

Dominance of chemokine ligand 2 and matrix metalloproteinase-2 and -9 and suppression of pro-inflammatory cytokines in the epidural compartment after intervertebral disc extrusion in a canine model.

BACKGROUND CONTEXT: In canine intervertebral disc (IVD) disease, a useful animal model, only little is known about the inflammatory response in the epidural space. PURPOSE: To determine messenger RNA (mRNA) expressions of selected cytokines, chemokines, and matrix metalloproteinases (MMPs) qualitatively and semiquantitatively over the course of the disease and to correlate results to neurologic status and outcome. STUDY DESIGN/SETTING: Prospective study using extruded IVD material of dogs with thoracolumbar IVD extrusion. PATIENT SAMPLE: Seventy affected and 13 control (24 samples) dogs. OUTCOME MEASURES: Duration of neurologic signs, pretreatment, neurologic grade, severity of pain, and outcome were recorded. After diagnostic imaging, decompressive surgery was performed. METHODS: Messenger RNA expressions of interleukin (IL)-1ß, IL-2, IL-4, IL-6, IL-8, IL-10, tumor necrosis factor (TNF), interferon (IFN)γ, MMP-2, MMP-9, chemokine ligand (CCL)2, CCL3, and three housekeeping genes was determined in the collected epidural material by Panomics 2.0 QuantiGene Plex technology. Relative mRNA expression and fold changes were calculated. Relative mRNA expression was correlated statistically to clinical parameters. RESULTS: Fold changes of TNF, IL-1ß, IL-2, IL-4, IL-6, IL-10, IFNγ, and CCL3 were clearly downregulated in all stages of the disease. MMP-9 was downregulated in the acute stage and upregulated in the subacute and chronic phase. Interleukin-8 was upregulated in acute cases. MMP-2 showed mild and CCL2 strong upregulation over the whole course of the disease. In dogs with severe pain, CCL3 and IFNγ were significantly higher compared with dogs without pain (p=.017/.020). Dogs pretreated with nonsteroidal anti-inflammatory drugs revealed significantly lower mRNA expression of IL-8 (p=.017). CONCLUSIONS: The high CCL2 levels and upregulated MMPs combined with downregulated T-cell cytokines and suppressed pro-inflammatory genes in extruded canine disc material indicate that the epidural reaction is dominated by infiltrating monocytes differentiating into macrophages with tissue remodeling functions. These results will help to understand the pathogenic processes representing the basis for novel therapeutic approaches. The canine IVD disease model will be rewarding in this process.

Non-pharmacological treatment options for refractory epilepsy: an overview of human treatment modalities and their potential utility in dogs.

Refractory epilepsy is a common disorder both in humans and dogs and treatment protocols are difficult to optimise. In humans, different non-pharmacological treatment modalities currently available include surgery, the ketogenic diet and neurostimulation. Surgery leads to freedom from seizures in 50-75% of patients, but requires strict patient selection. The ketogenic diet is indicated in severe childhood epilepsies, but efficacy is limited and long-term compliance can be problematic. In the past decade, various types of neurostimulation have emerged as promising treatment modalities for humans with refractory epilepsy. Currently, none of these treatment options are used in routine daily clinical practice to treat dogs with the condition. Since many dogs with poorly controlled seizures do not survive, the search for alternative treatment options for canine refractory epilepsy should be prioritised. This review provides an overview of non-pharmacological treatment options for human refractory epilepsy. The current knowledge and limitations of these treatments in canine refractory epilepsy is also discussed.

Idiopathic generalised tremor syndrome in two cats.

Two male neutered domestic shorthair cats were evaluated for generalised tremors. On neurological examination both cats showed whole-body tremors, worsening with stress. A mainly cerebellar disorder was suspected. Blood examination, cerebrospinal fluid analysis and electrophysiological examination of both cats and magnetic resonance imaging of the brain in one cat were normal. Idiopathic generalised tremor syndrome (IGTS) was suspected owing to the exclusion of underlying causes and the clinical similarities with the syndrome in dogs. Treatment as recommended for dogs was initiated and resulted in improvement. This report describes the first cases of IGTS in cats.

Regional brain perfusion in epileptic dogs evaluated by technetium-99m-ethyl cysteinate dimer SPECT.

We evaluated the feasibility of interictal single photon emission computed tomography (SPECT) to detect alterations in regional cerebral blood flow and neuronal activity in dogs with idiopathic epilepsy. Twelve dogs with idiopathic epilepsy underwent interictal technetium-99m-ethyl cysteinate dimer SPECT of the brain. Different cortical regions of interest (ROIs), 1 ROI at the cerebellum and 1 ROI at the subcortical area were evaluated by semiquantitative analysis and compared with a control group (18 dogs). Significant hypoperfusion (P = 0.02) was present in the subcortical area of epileptic dogs. This hypoperfusion was not associated with seizure frequency, age at onset of seizures, duration of epilepsy, or time since the last seizure. Interictal SPECT did not reveal cortical or cerebellar perfusion alterations. The subcortical area may play an important role in the pathophysiology of canine idiopathic epilepsy.

Surgical treatment of a canine intranasal meningoencephalocele.

OBJECTIVE: To report the clinical signs, diagnosis, and surgical treatment of an intranasal meningoencephalocele in a dog. STUDY DESIGN: Case report. ANIMAL: Female Border collie, 5 months old. METHODS: A right intranasal meningoencephalocele was identified by computed tomography and magnetic resonance imaging. RESULTS: The lesion was approached by a modified transfrontal craniotomy. Surgical closure of the defect at the level of the cribriform plate and removal of extruded brain tissue resulted in regression of lacrimation and coincided with absence of seizuring. Treatment with phenobarbital was gradually reduced and stopped at 7 months after surgery. At 28 months the dog remained free of seizures. CONCLUSION: Meningoencephalocele, although rare, can cause seizures in dogs and can be treated surgically. CLINICAL RELEVANCE: A transfrontal craniotomy with excision of the meningoencephalocele and closure of the defect can be an effective treatment for an intranasal meningoencephalocele in dogs.