Pathologic classification of a late-onset peripheral neuropathy in a spontaneous Labrador retriever dog model.

Late-onset peripheral neuropathy (LPN) is a heritable canine neuropathy commonly found in Labrador retrievers and is characterized by laryngeal paralysis and pelvic limb paresis. Our objective was to establish canine LPN as a model for human hereditary peripheral neuropathy by classifying it as either an axonopathy or myelinopathy and evaluating length-dependent degeneration. We conducted a motor nerve conduction study of the sciatic and ulnar nerves, electromyography (EMG) of appendicular and epaxial musculature, and histologic analysis of sciatic and recurrent laryngeal nerves in LPN-affected and control dogs. LPN-affected dogs exhibited significant decreases in compound muscle action potential (CMAP) amplitude, CMAP area, and pelvic limb latencies. However, no differences were found in motor nerve conduction velocity, residual latencies, or CMAP duration. Distal limb musculature showed greater EMG changes in LPN-affected dogs. Histologically, LPN-affected dogs exhibited a reduction in the number of large-diameter axons, especially in distal nerve regions. In conclusion, LPN in Labrador retrievers is a common, spontaneous, length-dependent peripheral axonopathy that is a novel animal model of age-related peripheral neuropathy that could be used for fundamental research and clinical trials.

Neurofilament light chain concentration does not correlate with disease status in Labrador Retrievers affected with idiopathic laryngeal paralysis.

OBJECTIVE: The aim of this study was to investigate whether plasma neurofilament light chain (pNfL) concentration was altered in Labrador Retrievers with idiopathic laryngeal paralysis (ILP) compared to a control population. A secondary aim was to investigate relationships between age, height, weight, and body mass index in the populations studied. ANIMALS: 123 dogs: 62 purebred Labrador Retrievers with ILP (ILP Cases) and 61 age-matched healthy medium- to large-breed dogs (Controls). METHODS: Dogs, recruited from August 1, 2016, to March 1, 2022, were categorized as case or control based on a combination of physical exam, neurologic exam, and history. Blood plasma was collected, and pNfL concentration was measured. pNfL concentrations were compared between ILP Cases and Controls. Covariables including age, height, and weight were collected. Relationships between pNfL and covariables were analyzed within and between groups. In dogs where 2 plasma samples were available from differing time points, pNfL concentrations were measured to evaluate alterations over time. RESULTS: No significant difference in pNfL concentration was found between ILP Cases and Control (P = .36). pNfL concentrations had moderate negative correlations with weight and height in the Control group; other variables did not correlate with pNfL concentrations in ILP Case or Control groups. pNfL concentrations do not correlate with ILP disease status or duration in Labrador Retrievers. CLINICAL RELEVANCE: There is no evidence that pNfL levels are altered due to ILP disease duration or progression when compared with healthy controls. When evaluating pNfL concentrations in the dog, weight and height should be considered.

Comparison of D-dimer concentration and thromboelastography for diagnosis of cerebrovascular accidents in dogs: A retrospective study.

BACKGROUND: Cerebrovascular accidents (CVAs) in dogs are diagnosed using magnetic resonance imaging (MRI). This modality is sometimes unavailable, and CVAs can resemble other lesions on MRI. D-dimer concentration and thromboelastography (TEG) are utilized in human medicine in addition to diagnostic imaging to support diagnosis of CVAs, but their use in veterinary patients has not been assessed. OBJECTIVE: Assess utility of blood D-dimer concentration and TEG in supporting the imaging diagnosis of CVAs in dogs. ANIMALS: Sixty-eight client-owned dogs with neurologic signs that had brain MRI and D-dimer concentration or TEG performed. METHODS: Multicenter, retrospective study. The incidence of abnormal D-dimer concentration or TEG was compared between patients with MRI evidence of CVA and a control population. Analysis methods included Fisher's exact test or Chi-squared test for association and comparison of independent proportions. RESULTS: Neither D-dimer concentration nor TEG was significantly associated with a CVA (P = .38 and .2, respectively). D-dimer testing was performed in a low-risk population and showed low sensitivity (30.8%; 95% confidence interval [CI], 10%-61%) and high specificity (86.4%; 95% CI, 64%-96%) for CVA diagnosis. Thromboelastography was performed in a high-risk population and showed moderate sensitivity (64.3%; 95% CI, 44%-81%) and specificity (66.7%; 95% CI, 24%-94%) for CVA diagnosis. Abnormal D-dimer concentration or TEG were not helpful in differentiating hemorrhagic from ischemic stroke (P = .43 and .41, respectively). CONCLUSIONS: Although blood D-dimer concentration or TEG alone are not diagnostic of CVAs in dogs, a positive D-dimer result supports additional testing for CVA.

No adverse consequences associated with targeting clinical signs to initiate antimicrobial treatment of postoperative subclinical bacteriuria in dogs following surgical decompression of Hansen type I thoracolumbar disk herniation.

OBJECTIVE: To describe the prevalence of postoperative bacteriuria, clinical course of subclinical bacteriuria in the absence of antimicrobial intervention, clinical signs of bacteriuria that trigger antimicrobial treatment, and outcomes for dogs with subclinical bacteriuria following surgical decompression of acute intervertebral disc herniation (IVDH) Hansen type I. ANIMALS: Twenty client-owned dogs undergoing hemilaminectomy for acute (≤ 6 days) IVDH Hansen type I affecting the thoracolumbar spinal cord segments between August 2018 and January 2019. PROCEDURES: In this prospective study, dogs were serially evaluated at presentation, hospital discharge, 2 weeks postoperatively, and between 4 and 6 weeks postoperatively. Dogs were monitored for clinical signs of bacteriuria, underwent laboratory monitoring (CBC, biochemical analyses, urinalysis, urine bacterial culture), and were scored for neurologic and urinary status. In the absence of clinical signs, bacteriuria was not treated with antimicrobials. RESULTS: Four of the 18 dogs developed bacteriuria without clinical signs 4 days to 4 to 6 weeks after surgery. In all 4 dogs, bacteriuria resulted in lower urinary tract signs 13 to 26 weeks postoperatively. No dogs had evidence of systemic illness despite delaying antimicrobial treatment until clinical signs developed. New-onset incontinence was the only clinical sign in 3 dogs. All bacterial isolates had wide antimicrobial susceptibility. Bacteriuria and clinical signs resolved with beta-lactam antimicrobial treatment. CLINICAL RELEVANCE: Postoperative bacteriuria occurs in some dogs with IVDH Hansen type I and, when present, may lead to clinical signs over time. Clinical signs of bacteriuria may be limited to new-onset urinary incontinence, inappropriate urination, or both. Delaying antimicrobial treatment until clinical signs of bacteriuria developed did not result in adverse consequences or systemic illness.

Case Report: Bordetella bronchiseptica Meningoencephalomyelitis in a Dog.

A 15-month-old male neutered Wirehaired Pointer mixed-breed dog presented with fever and cervical pain. Cerebrospinal fluid (CSF) analysis showed neutrophilic pleocytosis with intracellular bacteria, and culture of CSF grew Bordetella bronchiseptica. The patient became non-ambulatory 3 days after CSF collection. He was treated with low-dose prednisone for 3.5 months and doxycycline for 1 year. Recheck CSF analysis 1 month after diagnosis showed reduction of inflammation and 3 months after diagnosis revealed only increased protein. The patient improved neurologically over several months and was weakly ambulatory 5 months and fully ambulatory 7 months after diagnosis. Whole genome sequencing of the bacterial isolate and a live modified intranasal vaccine similar to the one the dog had been vaccinated with 7 weeks before diagnosis was similar but not an exact match. Bacterial meningitis should be considered, and culture of CSF is recommended, in cases of neutrophilic pleocytosis of CSF.

Cavernous sinus syndrome in dogs and cats: case series (2002-2015).

The cavernous sinus (CS) is a paired venous sinus that runs along either side of the pituitary gland on the floor of the calvarium. Cavernous sinus syndrome (CSS) refers to deficits in more than one of the cranial nerves III, IV, V, and VI, as they are in close association in this region. The purpose of this study was to identify the presenting complaints, neurologic findings, diagnosis, and outcomes in dogs and cats with confirmed cavernous sinus syndrome (CSS). Medical records between 2002 and 2015 were reviewed. Inclusion criteria were neurologic signs consistent with CSS and advanced imaging and/or post-mortem examination. Thirteen dogs and 2 cats were included. Twelve dogs received advanced imaging. Post-mortem examination was performed on 2 cats and 3 dogs. Dogs were 6 -13 years (mean= 10.8 years) of age and comprised of several different breeds. Both cats were male neutered domestic shorthair, ages 3 and 14 years. Presenting complaints included mydriasis (N=4), behavior changes (N=3), hyporexia (N=3), ptosis (N=2), ataxia (N=2), pain (N=2), weakness (N=2), lethargy (N=2), and one each of epiphora, ocular swelling, polydipsia, seizures, facial muscle atrophy, dysphagia, and head tilt. Neurologic signs included ophthalmoparesis/plegia (N=13), reduced/absent pupillary light response (N= 11), mydriasis (N= 10), reduced/absent corneal sensation (N= 7), ptosis (N= 6), reduced facial sensation (N= 2), and enophthalmos (N=1). Thirteen patients had a mass lesion within the cavernous sinus, 6 of which were confirmed neoplastic via histopathology. Median survival time for the 4 patients treated with radiation therapy was 1035 days (range 150-2280). Median survival for the 4 patients that received medical treatment was 360 days (range 7-1260 days), and for the 5 non-treated patients 14 days (range 0-90 days). In conclusion mydriasis and ophthalmoplegia are common signs of CSS. A mass lesion within the CS is the most common cause. Survival time may be improved with radiation therapy.

Fibrocartilaginous embolic encephalopathy of the cerebellum and brainstem in a cat.

A 12-year old male castrated Siamese cat was evaluated for a one-day history of mild obtundation and decerebellate rigidity. Neurological examination findings were consistent with multifocal disease including lesions within the right cerebellum and right brainstem. Investigations included hematology, biochemistry, urinalysis, and urine culture. A definitive diagnosis was not achieved clinically and differential diagnoses included vascular disease, neoplasia, and infectious disease. About nine hours after admission, the cat had an episode where it became rigid and then limp. The cat became agonal and went into cardiopulmonary arrest and attempts of resuscitation were unsuccessful. Post-mortem examination revealed evidence of multiple fibrocartilaginous emboli (FCE) within the cerebellum and within meningeal vessels on the ventral aspect of the brainstem. This is the first reported case of fibrocartilaginous embolism causing an encephalopathy in a cat. While this is a rare disease, it is an important differential diagnosis that should be considered in cases of acute encephalopathies in cats.

Neurological examination in healthy chinchillas ( Chinchilla lanigera).

Chinchillas are popular as laboratory models and companion animals, and they can be affected by a variety of infectious and non-infectious neurological diseases. Little information is available on making a neurological diagnosis in this species, in part because the neurological examination has not been standardized in chinchillas and the expected physiological findings in healthy chinchillas have not been reported. In this study, a standardized neurological examination was performed on 30 clinically normal chinchillas. The perineal reflex and the menace response were absent in all chinchillas evaluated and so should not be used as functional tests. Several tests were consistently positive, such as the oculocephalic reflex, maxillary, mandibular and auricular sensations, withdrawal reflexes, thoracic limb paw replacement, and the wheelbarrow test. Other tests, such as the cutaneous trunci reflex and pelvic limb paw replacement, had variable responses. Based on these findings, it is advised that clinicians prioritize tests that can be easily performed without undue stress to the animal, and give consistent results in a healthy patient.

Meningeal dissemination of a pituitary carcinoma to the cauda equina in a dog.

An 8-year-old spayed female border collie dog was diagnosed with an invasive pituitary macrotumor. Five months after radiation therapy, the patient developed paraparesis and lumbosacral pain. Necropsy revealed a pituitary carcinoma with cauda equina drop metastasis. In cases of pituitary masses, meningeal dissemination should be considered if neurologic status declines.

Dissémination méningée d'un carcinome pituitaire à la queue de cheval chez un chien. Une chienne Border collie stérilisée âgée de 8 ans a été diagnostiquée avec une macrotumeur pituitaire invasive. Cinq mois après la radiothérapie, la patiente a développé de la paraparésie et de la douleur lombo-sacrée. La nécropsie a révélé un carcinome pituitaire avec une métastase de la partie inférieure de la queue de cheval. Dans les cas des masses pituitaires, la dissémination méningée devrait être considérée s'il se produit un déclin de l'état neurologique.(Traduit par Isabelle Vallières).

Antemortem diagnosis of hydrocephalus in two Congo African grey parrots (Psittacus erithacus erithacus) by means of computed tomography.

CASE DESCRIPTION: A 7-year-old and a 10-year-old Congo African grey parrot (Psittacus erithacus erithacus; parrots 1 and 2, respectively) were evaluated because of neurologic deficits. CLINICAL FINDINGS: Parrot 1 had an 8- to 9-month history of lethargy and anorexia, with a recent history of a suspected seizure. Parrot 2 had a 6-month history of decreased activity and vocalizing, with an extended history of excessive water intake; a water deprivation test ruled out diabetes insipidus, and psychogenic polydipsia was suspected. Both birds had ophthalmologic asymmetry, with anisocoria detected in parrot 1 and unilateral blindness in parrot 2. Metal gastrointestinal foreign bodies were observed on whole-body radiographs of both birds, but blood lead concentrations were below the range indicated for lead toxicosis. Findings on CT of the head were consistent with hydrocephalus in both cases. TREATMENT AND OUTCOME: Parrot 1 received supportive care and died 3 months after the diagnosis of hydrocephalus. Parrot 2 was treated with omeprazole and prednisolone for 10 days without any improvement in neurologic deficits; euthanasia was elected, and hydrocephalus was confirmed on necropsy. No underlying or concurrent disease was identified. CLINICAL RELEVANCE: Hydrocephalus should be considered a differential diagnosis for parrots evaluated because of CNS signs. Computed tomography was an excellent screening tool to diagnose hydrocephalus in these patients. Compared with MRI, CT is more frequently available and offers reduced scanning times, reduced cost, and less concern for interference from metallic foreign bodies.

Osseous-associated cervical spondylomyelopathy in dogs: 27 cases (2000-2012).

OBJECTIVE: To evaluate the signalment, neurologic examination and imaging findings, and outcome in dogs treated medically or surgically for osseous-associated cervical spondylomyelopathy (OACSM). DESIGN: Retrospective case series. ANIMALS: 27 client-owned dogs. PROCEDURES: Medical records for dogs with OACSM (diagnosis made in 2000 through 2012) were reviewed. Collected data included signalment, neurologic examination findings (graded from 0 [normal] to 5 [tetraplegia]), imaging findings, treatment, and outcome. From MRI and CT images, measurements were obtained for subjective grading of spinal cord compression. RESULTS: Among the 27 dogs, the median age was 2 years; there were 15 Great Danes, 3 Mastiffs, 3 Newfoundlands, and 6 other large-breed dogs. For medically treated dogs (n = 7), the median initial neurologic grade was 2; for surgically treated dogs (20), the median initial neurologic grade was 3. Magnetic resonance imaging revealed dorsolateral spinal cord compression in 22 dogs and lateral spinal cord compression in 5 dogs. Dogs with more severe compressions were slightly more likely to undergo surgical than medical treatment. Median survival time of medically treated dogs was 43 months, and that of surgically treated dogs was 60 months. Fifteen of 19 dogs treated surgically had improved neurologic grades at 4 to 8 weeks after surgery and had a good to excellent long-term outcome. CONCLUSIONS AND CLINICAL RELEVANCE: Surgical treatment of dogs with OACSM resulted in neurologic improvement and was associated with a good long-term outcome. For dogs that received medical treatment, neurologic deterioration continued but some patients did well for several years.

Surgical management of vertebral synovial cysts in a rabbit (Oryctolagus cuniculus).

CASE DESCRIPTION: An approximately 8-month-old female Miniature Lop rabbit (Oryctolagus cuniculus) was evaluated because of an acute onset of progressive paraparesis. CLINICAL FINDINGS: The rabbit was ambulatory paraparetic, and results of neurologic examination were consistent with a myelopathy localizing to the T3-L3 spinal cord segments. Evaluation with CT myelography revealed focal extradural spinal cord compression bilaterally at the level of the articular process joints of T12-L1. TREATMENT AND OUTCOME: A Funkquist type A dorsal laminectomy was performed at T12-L1, and the vertebral column was stabilized with pins and polymethylmethacrylate-based cement. Multiple vertebral synovial cysts were confirmed on histologic evaluation of the surgically excised tissues. The rabbit was nonambulatory with severe paraparesis postoperatively and was ambulatory paraparetic at a recheck examination 7 weeks after surgery. Fourteen weeks after surgery, the rabbit appeared stronger; it walked and hopped slowly but still fell and dragged its hindquarters when moving faster. Thirty-seven weeks after surgery, the neurologic status was unchanged. CLINICAL RELEVANCE: Although thoracolumbar myelopathy in rabbits is commonly secondary to vertebral fracture, vertebral synovial cysts should be considered a differential diagnosis for rabbits with slowly progressive paraparesis. Decompressive surgery and stabilization can result in a good outcome for rabbits with this condition.

Feline ischemic myelopathy and encephalopathy secondary to hyaline arteriopathy in five cats.

Five cats presented with acute-onset neurological signs. Magnetic resonance imaging in four cats showed a T2-weighted hyperintense spinal cord lesion that was mildly contrast-enhancing in three cats. Owing to inflammatory cerebrospinal fluid changes three cats were treated with immunosuppression. One cat was treated with antibiotics. All cats improved initially, but were eventually euthanased owing to the recurrence of neurological signs. Histopathology in all cats showed hyaline degeneration of the ventral spinal artery, basilar artery or associated branches with aneurysmal dilation, thrombosis and ischemic degeneration and necrosis of the spinal cord and brain. Two cats also had similar vascular changes in meningeal vessels. Vascular hyaline degeneration resulting in vascular aneurysmal dilation and thrombosis should be a differential diagnosis in cats presenting with acute central nervous system signs.

Evaluation of therapeutic phenobarbital concentrations and application of a classification system for seizures in cats: 30 cases (2004-2013).

OBJECTIVE: To determine the percentage of cats with a phenobarbital (PB) concentration between 15 and 45 µg/mL that had a ≥ 50% reduction in the number of seizures and to investigate applicability of the 2011 International League Against Epilepsy (ILAE) classification system in cats. DESIGN: Retrospective case series. ANIMALS: 30 cats with suspected or confirmed epilepsy. PROCEDURES: Medical records for 2004 to 2013 at 3 veterinary hospitals were searched. Information collected included signalment, duration of observation before treatment, frequency of seizures before PB administration, seizure phenotype, dose of PB, serum PB concentration, number of seizures after PB administration, duration of follow-up monitoring, and survival time. A modified 2011 ILAE classification system was applied to all cats. RESULTS: Seizure control was achieved in 28 of 30 (93%) cats with a serum PB concentration of 15 to 45 µg/mL. This comprised 10 of 11 cats with structural epilepsy, 14 of 15 cats with unknown epilepsy, and 4 of 4 cats with presumptive unknown epilepsy. Thirteen cats had no additional seizures after initiation of PB treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Seizure control was achieved in most cats with a serum PB concentration between 15 and 45 µg/mL, regardless of the cause of the seizures. A modified 2011 ILAE classification was applied to cats with seizures and enabled classification of cats without specific genetic testing and without identified structural or inflammatory disease. This classification system should be incorporated into veterinary neurology nomenclature to standardize communication between veterinarians and improve comparisons among species.

Diagnosis and surgical treatment of an intracranial cyst in an alpaca cria.

CASE DESCRIPTION: A 7-day-old female alpaca was examined because of an acute onset of diffuse central neurologic deficits. CLINICAL FINDINGS: Diagnostic imaging with CT and MRI identified an intracranial cyst occupying approximately one-third to one-half of the dorsal portion of the cranial cavity, markedly displacing the cerebral hemispheres bilaterally. TREATMENT AND OUTCOME: Initial surgical management via trephination and needle drainage was only transiently effective at resolving the neurologic signs. Craniotomy and drainage and removal of the cyst lining resulted in a sustained improvement in neurologic status, and the cria remained clinically normal and well grown at follow-up 5 months after surgery. CLINICAL RELEVANCE: This report represented the first description of the successful treatment of an intracranial cyst in a New World camelid.

Intramedullary epidermoid cyst in the thoracic spine of a dog.

A 5 yr old female spayed mastiff was evaluated for a 3-4 mo history of paraparesis and 3 days of acutely worse paraparesis and incontinence. On magnetic resonance imaging, a spinal cord lesion was present at the ninth thoracic vertebra. The lesion was hyperintense on T2-weighted images (T2-W), and a hyperintense rim was present on T1-weighted postcontrast images. Histologic examination showed a cystic mass lined by squamous epithelial cells. Histopathologic diagnosis was an intramedullary epidermoid spinal cyst. Epidermoid cyst should be a differential diagnosis in young dogs with a myelopathy and an intramedullary spinal cord lesion on magnetic resonance imaging examination.

Granular cell tumor in a lumbar spinal nerve of a dog.

A 2-year-old Great Dane dog with a 2.5-week history of progressive paraparesis was presented to the Veterinary Medical Teaching Hospital at the University of Wisconsin-Madison. Neurologic examination revealed nonambulatory paraparesis with reduced to absent withdrawal hind-limb reflexes and lumbar pain. Magnetic resonance imaging and gross pathology confirmed a larger regional lumbar mass and a second smaller extradural mass within the spinal canal. The left lumbar mass was associated with extensive hemorrhage; dissection showed a dark-red, soft, well-circumscribed mass measuring 2 cm x 1.5 cm x 0.5 cm within the left fourth lumbar spinal nerve. Histopathological evaluation with immunohistochemistry revealed sheets of round to polygonal cells with diffuse granular cytoplasm demonstrating diastase-resistant periodic acid-Schiff reactivity and positive immunoexpression of S100 and neuron-specific enolase. The smaller extradural mass within the spinal canal exhibited similar morphology. Based on gross, histological, and immunohistochemical evidence, the masses were diagnosed as granular cell tumor.

Evaluation of different computed tomography techniques and myelography for the diagnosis of acute canine myelopathy.

Forty-six dogs with either cervical (C1-C5 or C6-T2) or thoracolumbar (T3-L3) acute myelopathy underwent prospective conventional computed tomography (CT), angiographic CT, myelography, and CT myelography. Findings were confirmed at either surgery or necropsy. Seventy-eight percent of lesions were extradural, 11% were extradural with an intramedullary abnormality, 7% were intramedullary, 2% were intradural-extramedullary, and 2% had nerve root compression without spinal cord compression. Intervertebral disc herniation was the most frequent abnormality regardless of signalment or neurolocalization. Twenty-one of 23 Hansen type I disc extrusions but none of the Hansen type II disc protrusions were mineralized. Two chondrodystrophic dogs had acute myelopathy attributable to extradural hemorrhage and subarachnoid cyst. CT myelography had the highest interobserver agreement, was the most sensitive technique for identification of compression, demonstrating lesions in 8% of dogs interpreted as normal from myelography and enabling localization and lateralization in 8% of lesions incompletely localized on myelography due to concurrent spinal cord swelling. None of the imaging techniques evaluated permitted definitive diagnosis of spinal cord infarction or meningomyelitis but myelography and CT myelography did rule out a surgical lesion in those cases. While conventional CT was adequate for the diagnosis and localization of mineralized Hansen type I disc extrusions in chondrodystrophic breeds, if no lesion was identified, plegia was present due to concurrent extradural compression and spinal cord swelling, or the dog was nonchondrodystrophic, CT myelography was often necessary for correct diagnosis.