Cervical hyperaesthesia in dogs: an epidemiological retrospective study of 185 cases.

OBJECTIVES: To describe the prevalence, clinical findings and predictors of disease in dogs with cervical hyperaesthesia. MATERIALS AND METHODS: Medical records of dogs referred for neurological investigation of cervical hyperaesthesia between 2009 and 2013 were retrospectively reviewed. Dogs were assigned to one of the following groups according to the final diagnosis: Non-Neurologic, Brain, Cervical Spine, Multifocal, and Chiari-like Malformation/Syringomyelia. Demographic data, clinical and neurological signs and laboratory findings were compared between groups using univariate analysis; predictors of disease location were assessed by multivariate analysis. RESULTS: Final diagnostic allocations of the 185 records included in the study were as follows: 2.7% Non-Neurologic, 2.2% Brain, 63.2% Cervical Spine, 22.2% Multifocal and 9.7% Chiari Malformation/Syringomyelia. Intervertebral disc extrusion and steroid-responsive meningitis arteritis were the most common diseases. Compared to Multifocal dogs, those allocated a Cervical Spine diagnosis were older, heavier, more frequently ataxic and lame on a thoracic limb; furthermore, they were less frequently depressed or hyperthermic at presentation. Leucocytosis, neutrophilia and monocytosis were more frequent in dogs allocated a Multifocal diagnosis. Dogs with cervical hyperaesthesia older than 36 months and non-hyperthermic at presentation were more likely to have a lesion of the cervical region rather than a multi-focal disease. CLINICAL SIGNIFICANCE: Although non-specific, these results may be useful to guide clinicians in management of dogs presenting with cervical hyperaesthesia. Animal age and body temperature may support the suspicion of either focal or multi-focal cervical spinal disease.

Low-field magnetic resonance changes in the paravertebral musculature of dogs with acute intervertebral disc extrusion.

OBJECTIVES: To describe the MRI features and prevalence of paravertebral muscle signal intensity changes in dogs with acute intervertebral disc extrusion and to search for associations between the signal changes and clinical history, signalment, neurological examination, serum creatine kinase activity and MRI characteristics of the disc herniation. MATERIALS AND METHODS: Medical records and MRI examinations from 688 dogs with surgically confirmed acute intervertebral disc extrusion were reviewed retrospectively. T2-weighted and STIR MRI sequences were available for 276 cases and were examined for paravertebral muscle signal intensity changes. When present, extension, lateralisation and signal characteristics of these changes were recorded. Exclusion criteria were muscle injections 24 hours before MRI scan, trauma and previous spinal surgery. RESULTS: Nineteen dogs met the inclusion criteria. There were signal changes in the multifidus muscle, mostly in the thoracolumbar region and often extending caudally from the level of the intervertebral disc herniation. Two cases had paravertebral muscle signal intensity changes in the cervical region. MRI signal changes were seen more frequently in the muscles of non-ambulatory dogs. Clinical history and neuro-examination did not allow differentiation between dogs with and without paravertebral muscle signal intensity changes. CLINICAL SIGNIFICANCE: Paravertebral muscle signal intensity changes were observed infrequently in the epaxial musculature of 6.9% dogs with acute intervertebral disc extrusion in both the thoracolumbar and cervical regions. The pathophysiological processes responsible for these MRI changes remain unknown.

Effect of 5% transdermal lidocaine patches on postoperative analgesia in dogs undergoing hemilaminectomy.

OBJECTIVES: To investigate the effect of 5% lidocaine patches on postoperative analgesia in dogs undergoing hemilaminectomy. MATERIALS AND METHODS: Client-owned dogs undergoing hemilaminectomy for a single acute intervertebral thoracolumbar disc extrusion were enrolled in this prospective, randomised, blinded clinical trial. Following methadone administration, anaesthesia was induced with propofol, and maintained with isoflurane in oxygen and fentanyl infusion, in both groups. After skin closure, two 1∙5 cm wide 5% lidocaine patch strips were attached along both sides of the wound in dogs allocated to Group L. In Group C, the two lidocaine patch strips were applied but the transparent isolating liner was not removed. Postoperatively, all dogs received a non-steroidal anti-inflammatory drug, gabapentin and diazepam. Methadone was administered according to the short form of Glasgow Composite Pain Scale with pain assessed every 2 hours for 48 hours by observers unaware of the treatment. RESULTS: Thirty-nine dogs completed the study. Demographic data, end-expiratory fraction of isoflurane, fentanyl consumption, anaesthesia and surgical times were similar between groups. The number of dogs requiring postoperative methadone and the number of doses of methadone administered were not different between groups. No macroscopic skin reaction was noticed once the patches were removed. CLINICAL SIGNIFICANCE: In this setting, 5% lidocaine patches did not provide additional postoperative analgesia in dogs undergoing hemilaminectomy.

Metronidazole-induced neurotoxicity in 26 dogs.

BACKGROUND: Metronidazole is an antibacterial, antiprotozoal and anthelmintic medication commonly used in veterinary medicine. We describe cases of neurotoxicity associated with the drug's administration. METHODS: Medical records between 2004 and 2017 from four veterinary referral hospitals were reviewed. Inclusion criteria were the presence of neurological signs compatible with metronidazole toxicity, clinical history supporting recent metronidazole therapy and resolution of clinical signs upon discontinuation of metronidazole administration. RESULTS: A total of 26 dogs were identified with clinical signs supporting a diagnosis of metronidazole toxicity. Median age at presentation was 7.2 years (range, 0.1-12 years); median duration of treatment was 35 days (range, 5-180 days); median treatment dosage was 21 mg/kg BID (range, 13-56 mg/kg every 12 h); median resolution of the clinical signs upon discontinuation of metronidazole was 3 days (range, 1-26 days). Magnetic resonance imaging (MRI) of the brain was performed in 19 cases and only one dog had brain lesions affecting the dentate nuclei, which resembled the MRI appearance of this disease in humans. CONCLUSIONS: We found evidence of neurotoxicity in dogs at much lower doses than previously reported and we suggest caution when administering metronidazole at doses > 40 mg/kg every 24 h, regardless of the duration of the treatment.

Development of a deep convolutional neural network to predict grading of canine meningiomas from magnetic resonance images.

An established deep neural network (DNN) based on transfer learning and a newly designed DNN were tested to predict the grade of meningiomas from magnetic resonance (MR) images in dogs and to determine the accuracy of classification of using pre- and post-contrast T1-weighted (T1W), and T2-weighted (T2W) MR images. The images were randomly assigned to a training set, a validation set and a test set, comprising 60%, 10% and 30% of images, respectively. The combination of DNN and MR sequence displaying the highest discriminating accuracy was used to develop an image classifier to predict the grading of new cases. The algorithm based on transfer learning using the established DNN did not provide satisfactory results, whereas the newly designed DNN had high classification accuracy. On the basis of classification accuracy, an image classifier built on the newly designed DNN using post-contrast T1W images was developed. This image classifier correctly predicted the grading of 8 out of 10 images not included in the data set.

Magnetic resonance imaging, treatment and outcome of canine vertebral chondrosarcomas. Six cases.

OBJECTIVES: To report the clinical presentation, magnetic resonance imaging features, treatments and outcomes of canine vertebral chondrosarcoma. MATERIALS AND METHODS: Retrospective review of medical records of dogs with confirmed vertebral chondrosarcoma and magnetic resonance imaging of the lesions, from four different veterinary referral institutions. RESULTS: A total of six dogs were included in this report. In all cases, magnetic resonance imaging revealed a lobulated mass involving the dorsal vertebral compartment, markedly hyperintense with few foci of hypointensity on T2-weighted images, iso to hypointense on T1-weighted images with contrast enhancement after gadolinium administration. Intralesional surgical resection was performed in three dogs and medical management in one, two dogs were euthanased and all lesions were submitted for histopathology. Magnetic resonance imaging findings correlated with histological findings of a low tumour grade. Rapid clinical improvement was noted after surgery but two of three dogs had local regrowth. CLINICAL SIGNIFICANCE: Chondrosarcomas show local aggressiveness and resistance to conventional radiotherapy and chemotherapy, and so prognosis depends on feasibility of en bloc resection. Magnetic resonance imaging may be helpful in establishing a presumptive diagnosis and prognosis based on the feasibility of surgical resection.

Safety of intrathecal administration of cytosine arabinoside and methotrexate in dogs and cats.

The objective of the study was to retrospectively evaluate the short-term safety of intrathecal administration of cytosine arabinoside alone or in combination with methotrexate in dogs and cats. One hundred and twelve dogs and eight cats admitted between September 2008 and December 2013, diagnosed with suspected inflammatory (meningoencephalomyelitis of unknown aetiology) or neoplastic disease affecting brain or spinal cord and treated with an intrathecal administration of cytosine arabinoside alone or in combination with methotrexate were included in the study. Recorded information regarding possible adverse events during administration while recovering from anaesthesia and during hospitalization period were evaluated. The results showed that one patient developed generalized tonic-clonic seizure activity after administration of cytosine arabinoside and methotrexate during recovery from anaesthesia, however responded to intravenous administration of diazepam. On the base of our results we can conclude that intrathecal administration of cytosine arabinoside alone or in combination with methotrexate is a safe procedure in dogs and cats.

Omentalisation in the treatment of sublumbar abscessation: long-term outcome in 10 dogs.

The objectives of this study were to report the technique of omentalisation for the management of sublumbar abscessation associated with suspected migrating plant material, the intraoperative and postoperative complications that occurred and the long-term outcome of the cases. A retrospective case series of dogs (n=10) with sublumbar abscessation managed by exploration and drainage combined with omentalisation of the abscess cavity is reported in this study. The sublumbar area was approached through a ventral midline coeliotomy, the abscess was explored, drained, debrided and subsequently packed with omentum. One dog sustained an aortic rupture during exploration of the abscess, the aorta was repaired; there were no postoperative complications. There was long-term (>12 months) resolution of clinical signs in all dogs. Drainage and omentalisation of sublumbar abscesses resulted in complete resolution of signs in all dogs and was associated with a low incidence of complications. Omentalisation is an effective treatment for dogs presenting with sublumbar abscesses associated with suspected migrating plant material.

STIR muscle hyperintensity in the cervical muscles associated with inflammatory spinal cord disease of unknown origin.

OBJECTIVES: To assess the relation of a distinctive pattern of short tau inversion recovery muscle hyperintensity with inflammatory cerebrospinal fluid result in dogs. METHODS: All dogs that had a short tau inversion recovery sequence performed in addition to other magnetic resonance sequences of the cervical spine and concurrent cerebrospinal fluid evaluation during the study period were included. All magnetic resonance studies were anonymised and reviewed by a board certified radiologist and board certified neurologist. A board certified pathologist examined the cerebrospinal fluid and the results were reviewed. RESULTS: Forty-nine cases fulfilled the inclusion criteria. Repeatable patterns of short tau inversion recovery hyperintensity were identified in 20 dogs. The clinical diagnosis in all these 20 cases was of meningoencephalomyelitis of unknown origin. This diagnosis was confirmed by inflammatory cerebrospinal fluid changes in 18 and suspected from clinical presentation and response to therapy in the remaining 2. CLINICAL SIGNIFICANCE: In this study, the short tau inversion recovery changes identified were restricted to cases with inflammatory spinal cord disease. The short tau inversion recovery change had a sensitivity of 78%, and a specificity of 92% in predicting inflammatory cerebrospinal fluid, suggesting that short tau inversion recovery sequences are a useful addition to the investigation of suspected inflammatory spinal cord disease.

Centronuclear myopathy in a Border collie dog.

A two-year old, male entire Border collie was presented with a one-year history of exercise-induced collapsing on the pelvic limbs. Physical examination revealed generalised muscle atrophy. Neurological examination supported a generalised neuromuscular disorder. Electromyography revealed spontaneous electrical activity in almost all muscles. Unfixed and formaldehyde-fixed biopsy samples were collected from the triceps brachii, longissimus and vastus lateralis muscles. Histopathological, histochemical and ultrastructural examinations of biopsy specimens were consistent with either centronuclear or myotubular myopathy. The dog clinically improved with supportive treatment with L-carnitine, co-enzyme Q10 and vitamin B compound. To the authors' knowledge, this is the first report of centronuclear/myotubular myopathy in a Border collie.

The cutaneous trunci reflex for localising and grading thoracolumbar spinal cord injuries in dogs.

OBJECTIVES: To evaluate the accuracy of the cutaneous trunci reflex to localise thoracolumbar spinal cord injuries and to assess the correlation between focal loss (cut-off) of the reflex and clinical severity of thoracolumbar spinal cord injury. METHODS: Prospective study of 41 dogs with thoracolumbar spinal cord injuries investigated by magnetic resonance imaging. Linear regression analysis was performed to determine the relationship between the vertebral level of the cutaneous trunci reflex cut-off and the maximal and cranial lesion extent. The association between cutaneous trunci reflex cut-off and spinal cord injury severity was tested using a Mann-Whitney U test. RESULTS: Cutaneous trunci reflex cut-off was evident in 33 (80%) of dogs. The cut-off level was 0 to 4 vertebrae caudal to the maximal spinal cord lesion in all dogs. In 16 (48.5%) dogs the cut-off was either 2 or 3 vertebrae caudal to the lesion. The presence of a cut-off significantly correlated with increasing severity (P=0.0001). Loss of the reflex occurred at less severe grades than loss of ambulation and in dogs with ambulatory paresis it was significantly (P=0.0084) associated with increasing severity. CLINICAL SIGNIFICANCE: The cutaneous trunci reflex allows localisation of thoracolumbar spinal cord lesions within four vertebrae and facilitates clinical segregation of dogs with ambulatory paresis into mild and severe categories.

Comparison of magnetic resonance imaging sequences in dogs with multi-focal intracranial disease.

OBJECTIVES: To compare the value of different magnetic resonance sequences in the detection of brain lesions in dogs with multi-focal intracranial neurolocalised lesions and abnormal cisternal cerebrospinal fluid analysis. METHODS: T2-weighted, T1-weighted, T1-weighted-Gd, FLAIR (fluid attenuated inversion recovery) images of 73 dogs with multi-focal intracranial localised lesions were reviewed retrospectively. Control dogs (19) were selected on the basis of normal neurological examination, magnetic resonance images and cerebrospinal fluid analysis. Two board-certified radiologists blindly reviewed the magnetic resonance images. Magnetic resonance sequence sensitivities were compared using the chi-squared test and logistic regression, accounting for clustering at the patient level. Statistical significance was set at the 5 per cent level. RESULTS: The FLAIR sequence was found to have the highest sensitivity (84 per cent, 61 of 73), followed by T2-weighted (63 per cent, 46 of 73), T1-weighted postcontrast (62 per cent, 45 of 73) and T1-weighted (23 per cent, 17 of 73) (P<0.001). FLAIR images were 106.1 times (95 per cent confidence interval 25.2 to 447.5) more likely to correctly identify cerebrospinal fluid-positive patients than T1-weighted, 6.4 times (95 per cent confidence interval 2.2 to 18.2) than T1-weighted postcontrast and 5.8 times (95 per cent confidence interval 2.0 to 16.4) than T2-weighted. FLAIR identified 14 per cent of cases that were classified as normal based on the three others sequences. CLINICAL SIGNIFICANCE: Routine use of FLAIR sequence should be encouraged in dogs undergoing a brain magnetic resonance imaging and probably more specifically in cases of suspected inflammatory brain disease.

Autoimmune myasthenia gravis and dysautonomia in a dog.

A two-year-old male entire border collie dog was evaluated for a short history of mixed bowel diarrhoea, coughing, vomiting and stranguria. Physical examination revealed dyspnoea with increased ventral lung sounds and a flaccidly distended bladder. Neurological examination revealed poor pupillary light reflexes, an absent gag reflex and a poor anal tone. Thoracic radiography was consistent with megaoesophagus and aspiration pneumonia. Clinicopathological testing revealed an elevated muscular nicotinic acetylcholine receptor antibody titre. The dog was euthanased because of clinical deterioration. Cerebrospinal fluid (CSF) collected immediately post-mortem revealed macrophagic pleocytosis. Post-mortem histopathological examination was consistent with dysautonomia. This is the first report of coexisting autoimmune myasthenia gravis and dysautonomia in a non-human species. The concomitant diseases may suggest a common immunopathological aetiology.

Angiostrongylus vasorum causing meningitis and detection of parasite larvae in the cerebrospinal fluid of a pug dog.

This case report describes the presence of Angiostrongylus vasorum larvae in cerebrospinal fluid in an 11-month-old pug dog and the relative magnetic resonance images compatible with a focal meningitis. Clinical signs were compatible with a cerebellar lesion, and diagnosis was confirmed by parasitological analysis on faecal and endotracheal lavage samples. Treatment with fenbendazole and prednisolone resulted in a complete resolution of the clinical signs in two months time. A vasorum infection should be considered a possible aetiology of intracranial inflammation in dogs.

Neuropathological findings in a Staffordshire bull terrier with l-2-hydroxyglutaric aciduria.

l-2-Hydroxyglutaric aciduria (l-2-HGA) is a hereditary neurometabolic disorder reported in human beings and dogs. An 11-month-old Staffordshire bull terrier was suspected to have the disease, on the basis of clinical signs and magnetic resonance imaging findings. l-2-HGA was confirmed by urinary organic analysis and DNA testing and the dog was humanely destroyed. Post-mortem findings consisted only of microscopical lesions in the brain, characterized by marked spongiform changes and predominantly affecting the grey matter of the cerebral cortex, thalamus, cerebellum and brainstem. The spongiform changes were characterized by well-demarcated, clear vacuoles located at perineuronal and perivascular sites. Immunohistochemical and ultrastructural examination confirmed that the affected cells were astrocytes.

Five cases of canine dysautonomia in England (2004 to 2006).

Canine dysautonomia was diagnosed definitively in five dogs by histopathology. All dogs were seen between June 2004 and July 2006 and originated from south-east England; four dogs originated from an urban area and one from a rural area. Of the urban dogs, one had recently visited Scotland and one had visited a kennel in a rural area nearby. Acute-onset but progressive vomiting, diarrhoea, depression and inappetence were the most common presenting clinical signs. Reduced or absent anal tone, dysuria, absence of pupillary light reflexes with intact vision, mydriasis, decreased corneal sensitivity and nictitating membrane protrusion were among the most frequent neurological findings. Abnormalities in pharmacological autonomic and physiological function testing (including orthostatic hypotension in two dogs) and diagnostic imaging studies were detected in some of the animals. All dogs failed to respond adequately to treatment, and given the poor prognosis, they were eventually euthanased. Histopathology identified marked chromatolysis of ganglion cell bodies. This case series emphasises that dysautonomia should be considered when a dog is presented in the UK with acute- or subacute-onset gastrointestinal signs and compatible physical and neurological abnormalities.

Characteristics of magnetic resonance images of granulomatous meningoencephalomyelitis in 11 dogs.

The characteristics of magnetic resonance imaging (mri) of the brains and spinal cords of 11 dogs with histologically confirmed granulomatous meningoencephalomyelitis (gme) were determined. The lesions were in the brain of eight of the dogs, in the brain and spinal cord of two, and in the spinal cord alone in one dog. A single lesion was present in four of the dogs and multiple lesions were found in six. In one dog with intracranial signs, no visible lesions could be detected on mri. No meningeal enhancement was detected in T1-weighted images post-contrast, or in fluid attenuation inversion recovery (flair) images, but there were histological lesions in the meninges in nine of the dogs. The T2-weighted images and flair sequences were characterised in all cases by hyperintensity, whereas the signal intensity of the lesions on T1-weighted images was variable. After the administration of paramagnetic contrast, some of the lesions showed no enhancement, but others showed marked patterns of enhancement. The lesions in 10 of the dogs were easily identifiable by mri and the images had several unifying characteristics, but they could not be considered disease-specific.

Brain and spinal cord haemorrhages associated with Angiostrongylus vasorum infection in four dogs.

Multifocal haemorrhages associated with Angiostrongylus vasorum infection were observed in the central nervous system of four dogs with neurological signs including depression, seizures, spinal pain and paresis. In magnetic resonance images the majority of the lesions were isointense or slightly hyperintense in T1-weighted images, hyperintense in T2-weighted images and hypointense in T2*-weighted (gradient echo) images, compatible with haemorrhages more than seven days old. Lesions were found in the brain of three of the dogs and in the spinal cord of two. The cerebrospinal fluid contained high concentrations of protein and evidence of erythrophagia. All the dogs had coagulopathy and pulmonary haemorrhage of varying severity. A vasorum larvae were detected in the faeces of each of the dogs. Neural A vasorum was confirmed at postmortem examination in two dogs.