Tom Harcourt-Brown

Systematic Review of Brain Tumor Treatment in Dogs

Intracranial neoplasia is commonly diagnosed in dogs and can be treated by a variety of methods, but formal comparisons of treatment efficacy are currently unavailable. This review was undertaken to summarize the current state of knowledge regarding outcome after the treatment of intracranial masses in dogs, with the aim of defining optimal recommendations for owners. This review summarizes data from 794 cases in 22 previously published reports and follows PRISMA guidelines for systematic review. A Pubmed search was used to identify suitable articles. These then were analyzed for quality and interstudy variability of inclusion and exclusion criteria and the outcome data extracted for summary in graphs and tables. There was a high degree of heterogeneity among studies with respect to inclusion and exclusion criteria, definition of survival periods, and cases lost to follow‐up making comparisons among modalities troublesome. There is a need for standardized design and reporting of outcomes of treatment for brain tumors in dogs. The available data do not support lomustine as an effective treatment, but also do not show a clear difference in outcome between radiotherapy and surgery for those cases in which the choice is available.

What progress has been made in the understanding and treatment of degenerative lumbosacral stenosis in dogs during the past 30 years

An association between degenerative changes in the lumbosacral region of the vertebral column and clinical signs of pain and pelvic limb dysfunction has long been recognized in dogs and has become known as degenerative lumbosacral stenosis syndrome. Over the past two decades, methods of imaging this condition have advanced greatly, but definitive criteria for a reliable diagnosis using physical examination, imaging and electrodiagnostics remain elusive. Available treatment options have changed little over more than 30 years but, more importantly, there is a lack of comparative studies and little progress has been made in providing evidence-based recommendations for the treatment of affected dogs. This review provides an overview of the changes in diagnosis, understanding and treatment of lumbosacral disease in dogs over the past 30 years. Approaches to address the unanswered questions regarding treatment choice are also proposed.

Prevalence of Chiari-like Malformations in Clinically Unaffected Dogs

Background The importance of Chiari‐like malformation (CM) in the generation of clinical signs or the formation of syringomyelia in dogs is incompletely understood, partly because the prevalence of various CM definitions in unaffected dogs is unknown. Hypothesis/Objectives The aims were: to estimate the prevalence of CM in dogs asymptomatic for CM or syringomyelia, according to 3 currently used definitions; and, to investigate the effect of brachycephaly and head position during magnetic resonance (MR) imaging on estimates of the prevalence of CM. Animals One ninety‐nine client‐owned dogs without apparent signs of CM or syringomyelia. Methods Blinded, retrospective analysis. Archived MR images were analyzed for evidence of cerebellar indentation and impaction into or herniation through the foramen magnum. Logistic regression analysis was used to investigate the relationship of CM diagnosis with head position and the cranial index (a measure of brachycephaly). Results In 185 non‐Cavalier King Charles Spaniel (CKCS) dogs, indentation was identified in 44% (95% CI, 47–51%) and impaction in 22% (95% CI, 16–28%). No asymptomatic, non‐CKCS dogs showed herniation. Regression analysis showed a significant increase in the odds of indentation and impaction in an extended head position and as the cranial index increased (became more brachycephalic). Conclusions and Clinical Importance The high prevalence of cerebellar indentation and impaction suggests that they may be normal anatomical variations and therefore unsuitable as definitions of CM. We suggest that future research into CM in dogs should define cases and controls more strictly so that overlap between normal and abnormal animals is minimized.

Nodo-paranodopathy, internodopathy and cleftopathy: Target-based reclassification of Guillain–Barré-like immune-mediated polyradiculoneuropathies in dogs and cats

Recent views on Guillain-Barré syndrome (GBS) question the accuracy of classification into axonal and demyelinating subtypes that represent convergent neurophysiological phenotypes rather than immunological targets. Instead it has been proposed to clarify the primarily affected fibre subunit in nerve biopsies. As nerve biopsies rarely are part of routine work-up in human patients we evaluated tissues taken from companion animals affected by GBS-like polyradiculoneuropathy to screen for distribution of immune cells, targeted fibre components and segregating non-inflammatory lesions. We identified that immune responses were directed either at Schmidt-Lanterman clefts, the paranode-node complex or both. Based on infiltrative and non-inflammatory changes, four subtypes and/or stages were distinguished, some of which indicate localisation of primary target antigens while others represent convergent late stage pictures, as a consequence to epitope spreading. The impact of histological subtyping onto clinical management and prognosis remains to be evaluated in future clinical trials. Natural development and clinical manifestation of large animal dysimmune neuropathy may reflect human Guillain-Barré syndrome more accurately than experimental models and therefore provide complementary clues for translational research.

The Impact of Demographic, Social, and Environmental Factors on the Development of Steroid‐Responsive Meningitis‐Arteritis (SRMA) in the United Kingdom

Background Steroid‐responsive meningitis‐arteritis (SRMA) is an inflammatory disease of dogs that is suspected to be immune‐mediated. The development of other immune‐mediated diseases has been linked to vaccinations, time of the year, geographic location, sex, neuter status, and breed. Hypothesis/Objectives To identify if the development of SRMA is associated with time of year, vaccination, geographic location, sex, neuter status, and breed. Animals Sixty SRMA cases and 180 controls, all ≤24 months of age and matched for year of presentation, from a referral hospital population in the United Kingdom. Methods Retrospective case‐control study with unconditional logistic regression analysis. Results Beagles (P = .001), Border Collies (P = .001), Boxers (P = .032), Jack Russell Terriers (P = .001), Weimaraners (P = .048), and Whippets (P < .001) had significantly greater odds of developing SRMA in this population of dogs. Vaccination, time of year, geographic category, sex, and neuter status did not increase the odds of developing SRMA. Conclusions and Clinical Importance Only breed increased the odds of developing SRMA. It would be prudent to investigate the genetics of the identified breeds to help elucidate the etiopathogenesis of SRMA.

Screening diagnostics to identify triggers in 21 cases of steroid-responsive meningitis-arteritis

OBJECTIVES To evaluate whether screening tests used to identify infectious and neoplastic triggers for immune-mediated haemolytic anaemia, in particular a complete blood count and differential, serum biochemistry profile, urine analysis (including culture), abdominal ultrasound and thoracic radiographs, can identify triggers for steroid-responsive meningitis-arteritis. METHODS Retrospective descriptive review. RESULTS Twenty-one steroid-responsive meningitis-arteritis cases were identified in which all screening tests had been performed. All cases had changes in complete blood count (including neutrophilia, monocytosis, lymphocytosis, eosinopenia or anaemia); 19 had changes in biochemistry (including hypoalbuminaemia, hyperglobulinaemia, increased alkaline phosphatase activity, hyperphosphataemia, increased total calcium concentration, hypercholesterolaemia, hyperkalaemia, increased urea concentration and increased alanine aminotransferase activity); two cases had an elevated urine protein to creatinine ratio but none had positive urine culture results; no cases had abnormalities on orthogonal radiographs of the thorax; four cases had abnormalities identified on abdominal ultrasound, which following cytological examination suggested inflammation in the absence of pathological organisms. CLINICAL SIGNIFICANCE Screening tests used to identify infectious and neoplastic triggers in immune-mediated haemolytic anaemia did not isolate triggers for steroid-responsive meningitis-arteritis in the population of dogs under investigation.

Effects of syringomyelia on electrodiagnostic test results in Cavalier King Charles Spaniels

OBJECTIVE To determine the effects of syringomyelia on electromyography (EMG) findings, somatosensory-evoked potentials (SEPs), and transcranial magnetic motor-evoked potentials (TMMEPs) in Cavalier King Charles Spaniels (CKCSs). ANIMALS 27 client-owned CKCSs that underwent prebreeding magnetic resonance imaging screening or investigation of clinical signs consistent with syringomyelia. PROCEDURES In dogs with (n = 11) and without (16) magnetic resonance imaging-confirmed syringomyelia, the median nerve in each thoracic limb was stimulated and SEPs were recorded over the C1 vertebra; onset latency and latency and amplitude of the largest negative (N1) and positive (P1) peaks were measured. The TMMEPs were recorded bilaterally from the extensor carpi radialis and tibialis cranialis muscles; onset latencies in all 4 limbs were measured. Bilateral systematic needle EMG examination was performed on the cervical epaxial musculature, and the number of sites with spontaneous activity was recorded. RESULTS In dogs with syringomyelia, amplitudes of N1 and P1 and the amplitude difference between P1 and N1 were significantly smaller than those recorded for dogs without syringomyelia (approx 2-fold difference). No difference in SEP latencies, TMMEP latencies, or the proportion of dogs with > 2 sites of spontaneous activity detected during EMG examination was detected between groups. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that SEP amplitude at the C1 vertebra was a more sensitive measure of spinal cord function in CKCSs with syringomyelia, compared with results of EMG or TMMEP assessment. Measurement of SEP amplitude may have use as an objective assessment of the evolution and treatment of this disease.

An exploratory study into factors influencing development of acute canine polyradiculoneuritis in the UK

OBJECTIVES To investigate whether the development of acute canine polyradiculoneuritis is associated with various putative risk factors. MATERIALS AND METHODS Retrospective case-control study with conditional logistic regression analysis from a referral hospital population in the UK where controls were matched for year of presentation. RESULTS Forty-three cases were identified with acute canine polyradiculoneuritis and 86 controls were selected. Jack Russell terriers and West Highland white terriers were found to have a significantly greater odds of developing acute canine polyradiculoneuritis compared to a mixed baseline group of dogs. The odds of developing acute canine polyradiculoneuritis were greater in the autumn and winter compared to spring. Vaccination, rural/urban habitation, sex, neuter status and age were not associated with development of acute canine polyradiculoneuritis in our population of dogs. CLINICAL SIGNIFICANCE Breed and season were associated with development of acute canine polyradiculoneuritis. However, this is a small sample and so this observation needs confirmation in further studies and other factors may also be involved. Nevertheless, these findings may be important in further understanding the aetiopathogenesis of this condition.

Prognostic Factors Associated with Recovery of Ambulation and Urinary Continence in Dogs with Acute Lumbosacral Spinal Cord Injury

Background Limited information is available about prognostic factors for recovery after spinal cord injury (SCI) to the L4‐S3 segments. Previous research suggests that L4‐S3 SCI does not have a worse prognosis than T3‐L3 SCI. Hypothesis/Objectives To elucidate prognostic factors for regaining urinary continence and ambulation in dogs with L4‐S3 SCI and compare prognosis to T3‐L3 SCI. Animals/Methods A retrospective study on 61 nonambulatory dogs with L4‐S3 SCI, matched to dogs with T3‐L3 SCI, compared 3 weeks after onset. Prognostic factors explored using logistic regression and used for matching: nonchondrodystrophic dogs >15 kg versus dogs that were chondrodystrophic or <15 kg; compressive versus noncompressive lesions; presence versus absence of conscious pain perception (CPP); and lower vs upper motor neuron (LMN/UMN) incontinence. Results Fewer L4‐S3 dogs regained continence compared to T3‐L3 dogs (64 vs 85%, P = .0033), but no difference existed for regaining ambulation (66 vs 75%, P = .1306). In L4‐S3 SCI dogs, fewer dogs regained continence with loss of CPP (P < .001), LMN incontinence (P = .004), and noncompressive lesions (P = .006). Negative prognostic factors for regaining ambulation included absent CPP (P < .001) and large nonchondrodystrophic breed (P = .022). Conclusions and Clinical Importance Dogs with L4‐S3 SCI have a poorer short‐term prognosis than do dogs with T3‐L3 SCI. Dogs with L4‐S3 SCI had a poor prognosis with loss of CPP, or noncompressive lesions combined with LMN incontinence. Small‐breed or chondrodystrophic dogs with retained CPP, compressive lesions, and UMN incontinence had an excellent prognosis. These findings may help guide decision‐making in L4‐S3 SCI.

Choices and Decisions in Decompressive Surgery for Thoracolumbar Intervertebral Disk Herniation

Once decompressive surgery has been elected, the approach that maximizes the likelihood of gaining access to the herniated material for complete removal should be chosen. In most cases, a procedure that optimizes access to the ventrolateral aspect of the spinal cord will be advantageous but it is important to tailor the details of the surgical procedure to suit individual patients. Decompressive surgery for chronic (type II) herniations will frequently demand a ventral approach with partial corpectomy.