Nadia Shihab

Behavioral changes in dogs associated with the development of idiopathic epilepsy.

OBJECTIVES The aim of the study was to demonstrate behavioral changes with the development of epilepsy in dogs, a species proposed as a naturally occurring animal model for human epilepsy. METHODS Owners of dogs diagnosed with idiopathic epilepsy (n=80) completed a modified, previously-validated behavioral and seizure questionnaire. Principal axis factor analysis identified behavioral factors, the scores for which were compared before and after the development of epilepsy. RESULTS Drug-naïve dogs showed an increase in the behavior factors Fear/Anxiety, Defensive Aggression, and Abnormal Perception. In dogs receiving antiepileptic medication, there were still increases in Fear/Anxiety and Abnormal Perception, but no longer in Defensive Aggression. Additional increases were observed in Abnormal Reactivity, Attachment Disorder, Demented Behavior, and Apathetic Behavior. Pharmacoresistant dogs had larger increases in Controlling Aggression, Abnormal Perception, and Demented Behavior than drug responders. CONCLUSION Our data suggest that dogs, like humans and rodents, exhibit neurobehavioral comorbidities with the development of epilepsy.

Clinical risk factors associated with anti-epileptic drug responsiveness in canine epilepsy.

The nature and occurrence of remission, and conversely, pharmacoresistance following epilepsy treatment is still not fully understood in human or veterinary medicine. As such, predicting which patients will have good or poor treatment outcomes is imprecise, impeding patient management. In the present study, we use a naturally occurring animal model of pharmacoresistant epilepsy to investigate clinical risk factors associated with treatment outcome. Dogs with idiopathic epilepsy, for which no underlying cause was identified, were treated at a canine epilepsy clinic and monitored following discharge from a small animal referral hospital. Clinical data was gained via standardised owner questionnaires and longitudinal follow up data was gained via telephone interview with the dogs’ owners. At follow up, 14% of treated dogs were in seizure-free remission. Dogs that did not achieve remission were more likely to be male, and to have previously experienced cluster seizures. Seizure frequency or the total number of seizures prior to treatment were not significant predictors of pharmacoresistance, demonstrating that seizure density, that is, the temporal pattern of seizure activity, is a more influential predictor of pharmacoresistance. These results are in line with clinical studies of human epilepsy, and experimental rodent models of epilepsy, that patients experiencing episodes of high seizure density (cluster seizures), not just a high seizure frequency pre-treatment, are at an increased risk of drug-refractoriness. These data provide further evidence that the dog could be a useful naturally occurring epilepsy model in the study of pharmacoresistant epilepsy.

Treatment of Hydrocephalus with Ventriculoperitoneal Shunting in Twelve Dogs

OBJECTIVE To report use of ventriculoperitoneal shunt in dogs for management of hydrocephalus for which no cause could be identified. STUDY DESIGN Case series. ANIMALS Dogs with hydrocephalus (n=12). METHODS Medical records (June 2003-June 2009) were reviewed to determine preoperative clinical findings, initial postoperative, and long-term outcome. Additional follow-up information was obtained from owners and referring veterinarians. RESULTS All dogs had signs of forebrain dysfunction, 7 had vestibular signs and 3 had signs of spinal pain. Postoperative complications included pain (n=4), undershunting because of shunt kinking (n=1) and seizures (n=1). Initial improvement occurred in all dogs and was sustained in 9 dogs, 1 of which required revision surgery. CONCLUSIONS Sustained clinical improvement can be achieved in hydrocephalus with no active underlying cause by use of ventriculoperitoneal shunting.Objective: To report use of ventriculoperitoneal shunt in dogs for management of hydrocephalus for which no cause could be identified. Study Design: Case series. Animals: Dogs with hydrocephalus (n=12). Methods: Medical records (June 2003–June 2009) were reviewed to determine preoperative clinical findings, initial postoperative, and long-term outcome. Additional follow-up information was obtained from owners and referring veterinarians. Results: All dogs had signs of forebrain dysfunction, 7 had vestibular signs and 3 had signs of spinal pain. Postoperative complications included pain (n=4), undershunting because of shunt kinking (n=1) and seizures (n=1). Initial improvement occurred in all dogs and was sustained in 9 dogs, 1 of which required revision surgery. Conclusions: Sustained clinical improvement can be achieved in hydrocephalus with no active underlying cause by use of ventriculoperitoneal shunting.

How Long and Low Can You Go? Effect of Conformation on the Risk of Thoracolumbar Intervertebral Disc Extrusion in Domestic Dogs

Intervertebral disc extrusion (IVDE) is a common neurological disorder in certain dog breeds, resulting in spinal cord compression and injury that can cause pain and neurological deficits. Most disc extrusions are reported in chondrodystrophic breeds (e.g. Dachshunds, Basset Hounds, Pekingese), where selection for ‘long and low’ morphologies is linked with intervertebral discs abnormalities that predispose dogs to IVDE. The aim of this study was to quantify the relationship between relative thoracolumbar vertebral column length and IVDE risk in diverse breeds. A 14 month cross-sectional study of dogs entering a UK small animal referral hospital for diverse disorders including IVDE was carried out. Dogs were measured on breed-defining morphometrics, including back length (BL) and height at the withers (HW). Of 700 dogs recruited from this referral population, measured and clinically examined, 79 were diagnosed with thoracolumbar IVDE following diagnostic imaging ± surgery. The BL:HW ratio was positively associated with IVDE risk, indicating that relatively longer dogs were at increased risk, e.g. the probability of IVDE was 0.30 for Miniature Dachshunds when BL:HW ratio equalled 1.1, compared to 0.68 when BL:HW ratio equalled 1.5. Additionally, both being overweight and skeletally smaller significantly increased IVDE risk. Therefore, selection for longer backs and miniaturisation should be discouraged in high-risk breeds to reduce IVDE risk. In higher risk individuals, maintaining a lean body shape is particularly important to reduce the risk of IVDE. Results are reported as probabilities to aid decision-making regarding breed standards and screening programmes reflecting the degree of risk acceptable to stakeholders.

The association between Chiari-like malformation, ventriculomegaly and seizures in cavalier King Charles spaniels.

Cavalier King Charles spaniels (CKCSs) with Chiari-like malformation (CM) and associated seizures are frequently diagnosed with idiopathic epilepsy. There could be an association between ventriculomegaly (V) or caudal fossa overcrowding (CCFP) and seizures. A retrospective case-control study was performed using MRI to investigate the possible association between these morphological abnormalities and seizures. Seizure semiology and, where possible, electroencephalographic (EEG) abnormalities were documented. Eighty-five CKCS with CM were included, 27 with seizures. There was no association between V or CCFP and seizures (P=0.10 and 0.71, respectively). Seizures were classified as having partial onset in 61% of individuals in the study population (95% CI 42.41-76.43%). Another cause of recurrent seizures in CKCS (such as familial epilepsy) is suspected, as previously reported.

Responses to successive anti-epileptic drugs in canine idiopathic epilepsy

Pharmacoresistance to anti-epileptic drugs (AEDs) can be a source of frustration for owners and veterinarians alike in the treatment of canine idiopathic epilepsy (IE), with ongoing seizures having a significant negative impact upon the quality of life of affected dogs and owners (Chang and others 2006, Wessmann and others 2014). Finding an effective AED that reduces seizure frequency to an acceptable level (generally classed as more than 50 per cent reduction in veterinary medicine), or results in remission (seizure-freedom) can be a long process, with several AEDs trialled before optimum treatment is reached (Packer and others 2014). With more AEDs becoming available to veterinary patients, knowing whether (and when) to include further therapies can be challenging for practitioners, when faced with the balance between seizure control and side effect profiles. In human epilepsy, response rates to first-line and further AEDs have been studied in several populations, with the probability of seizure control diminishing progressively with successive AED treatments. Kwan and Brodie (2000) reported response rates (as a proportion of the population) of 47, 13 and 4 per cent for first-line, second-line and third-line drugs, respectively (Kwan and Brodie 2000). Similarly, Mohanraj and Brodie (2006) reported response rates of 50.4, 10.7 and 2.3 per cent, respectively, with just 0.8 per cent responding to any further drugs (Mohanraj and Brodie 2006). If the initial AED fails to control seizures, the prognosis for seizure control may be poor. Failure to respond to the first AED has been demonstrated to predict becoming refractory at two-year follow-up in a study of children with temporal lobe epilepsy (Dlugos and others 2001). In a further study, of those patients unresponsive to the first AED, 76 per cent failed two or more AEDs and 38 per cent failed at least four (Perucca and others 2011). These …

Surgical treatment of an intracranial epidermoid cyst in a dog.

OBJECTIVE To report challenges and complications associated with surgical intracranial epidermoid cyst removal from the fourth ventricle of a dog. STUDY DESIGN Clinical report. ANIMAL Labrador retriever (7 years old) with focal seizures. METHODS Magnetic resonance imaging (MRI) revealed an oval lesion in the fourth ventricle. This lesion was heterogeneously hyperintense on T2-weighted and fluid attenuation inversion recovery (FLAIR) images and hypointense on T1-weighted images. Dilatation of the ventricular system was present. A ventriculoperitoneal shunt (VPS) was placed and the fourth ventricle was approached by suboccipital craniectomy. An oval, white mass was identified in the fourth ventricle. Subtotal removal of the mass was performed. RESULTS On the day after surgery, neurologic deterioration was observed. The dog had severe cerebellar and brainstem dysfunction. Histopathologic examination of the removed tissue revealed an epidermoid cyst. The dog experienced gradual neurologic improvement; however, neurologic deterioration beginning at 6 months resulted in euthanasia 8 months after surgery. On necropsy, epidermoid cyst tissue was identified in the fourth ventricle. CONCLUSION Surgical removal of an intracranial epidermoid cyst may be complicated by adhesions between the cyst capsule and surrounding neurovascular structures, causing postoperative morbidity and eventual recurrence of clinical signs. These observations should be taken into account when considering surgical removal of an intracranial epidermoid cyst.

Surgical management of an incidentally diagnosed true pleuroperitoneal hernia in a cat

Diaphragmatic defects in cats are common and most frequently occur as a result of trauma.1 Congenital diaphragmatic defects include peritoneopericardial hernias, hiatal hernias and, infrequently, true diaphragmatic, or pleuroperitoneal, hernias. Only three reports of feline pleuroperitoneal hernias could be found in the veterinary literature.2–4 All of these cats presented for evaluation of respiratory distress and two were managed successfully with surgery. This report describes the incidental diagnosis and successfully surgical treatment of a pleuroperitoneal hernia in a cat. It highlights the fact that pleuroperitoneal hernias may not always be symptomatic and that they may not be as rare as previously considered.

Neuromuscular disorders in the cat: Clinical approach to weakness

Practical relevance Weakness is a relatively common clinical presentation in feline medicine and can be caused by primary neuromuscular disease or by diseases of other body systems affecting the neuromuscular system secondarily. Successful work-up relies on a thorough clinical and neurological examination, and logical problem solving, based on an understanding of the underlying neuroanatomical and pathophysiological mechanisms. Clinical challenges Feline neuromuscular diseases can be a diagnostic challenge. On initial inspection, the presenting signs can mimic disorders of other body systems, particularly cardiovascular, pulmonary and orthopaedic disease, or may be confused with systemic illnesses. Additionally, because many different pathologies of the feline neuromuscular system converge to a similar clinical phenotype, further diagnostic steps such as electrodiagnostics, cerebrospinal fluid analysis, and muscle and nerve biopsies must be considered even after neuromuscular dysfunction has been identified. Audience This review provides a framework for the clinical approach to the weak cat and gives a practical summary of neuromuscular diseases for the general practitioner and specialist alike. Evidence base Many diseases affecting the feline neuromuscular system have been well described in the veterinary literature, mostly based on retrospective case reports and series. The evidence base for the treatment of feline neuromuscular diseases remains very limited.

Imaging diagnosis-malignant peripheral nerve sheath tumor presenting as an intra-axial brain mass in a young dog

A 3-year-old Labrador retriever was presented with acute onset seizures. Magnetic resonance imaging demonstrated an intra-axial mass affecting the right temporal lobe of the brain. Surgical resection and histopathological findings were most consistent with a malignant peripheral nerve sheath tumor. After initial recovery, deterioration 3 months post surgery prompted euthanasia. Post-mortem revealed a mass protruding from the ventral surface of the temporal lobe, encroaching upon the optic chiasm and invading the brain. Histopathology findings were again consistent with malignant peripheral nerve sheath tumor. Although rare, this tumor should be included as a possible differential diagnosis for intra-axial brain masses in dogs.