ACVIM consensus statement on diagnosis and management of urinary incontinence in dogs.

Urinary incontinence (UI) is a disorder of micturition that can occur in dogs of any age, sex, and breed depending on the underlying cause and time of onset. Diagnosis and treatment for various causes of UI in dogs have been described by multiple comprehensive single author review articles, but large prospective clinical trials comparing treatment outcomes in veterinary medicine are lacking. The objectives of this consensus statement therefore are to provide guidelines on both recommended diagnostic testing and treatment for various causes of UI in dogs. Specifically, pathophysiology directly related to the canine urinary system will be reviewed and diagnostic and therapeutic challenges will be addressed. A panel of 12 experts in the field (8 small animal internists [L. Adams, J. Bartges, A. Berent, J. Byron, J. Foster, A. Kendall, S. Vaden, J. Westropp], 2 neurologists [J. Coates, N. Olby], 1 radiologist [G. Oetelaar], and 1 surgeon [C. Adin]) was formed to assess and summarize evidence in the peer-reviewed literature and to complement it with consensus recommendations using the Delphi method. Some statements were not voted on by all panelists. This consensus statement aims to provide guidance for management of both male and female dogs with underlying storage or voiding disorders resulting in UI.

Diagnosis and management of dogs with degenerative myelopathy: A survey of neurologists and rehabilitation professionals.

BACKGROUND: Antemortem diagnosis of degenerative myelopathy (DM) in dogs is presumptive and there are no accepted guidelines for the management of this condition. HYPOTHESIS/OBJECTIVES: Describe current practices of neurology clinicians and physical rehabilitation professionals in the diagnosis and management of DM. ANIMALS: None. METHODS: Online surveys examining diagnosis and management of DM were constructed and distributed via neurology and rehabilitation listservs. RESULTS: One hundred ninety neurology and 79 rehabilitation professionals from 20 countries participated. Most neurology (142/189) and rehabilitation (23/39) respondents required genetic testing for the superoxide dismutase 1 (SOD1) mutation and 82/189 neurologists also required spinal magnetic resonance imaging (MRI) for presumptive DM diagnosis. Most neurology respondents recommended exercise (187/190) and physical rehabilitation (184/190). Over 50% (102/190) of neurology respondents perform rechecks on dogs diagnosed with DM. Rehabilitation respondents reported preservation or improvement of strength (78/79) and coordination (77/79) as therapeutic goals. At-home exercises (75/79), underwater treadmill (64/79), gait training (55/79), and strength building exercises (65/79) were used to maintain strength (58/79), coordination (56/79), muscle mass (56/79), and improve overall wellbeing (54/79). Neurology respondents reported that owners elect euthanasia when dogs become nonambulatory paraparetic whereas rehabilitation respondents report euthanasia when paraplegia and incontinence develop. CONCLUSION AND CLINICAL IMPORTANCE: The majority of dogs diagnosed with DM have not undergone advanced imaging, the combination of history, neurological findings, and genetic testing is heavily relied upon. Whereas the diagnosis of DM is frequently made by veterinary neurologists, continued care is often performed by rehabilitation professionals or primary veterinarians.

Mycobacterium haemophilum infection in canine cerebrospinal fluid.

A 4-year-old female spayed Australian cattle dog was presented to the Emergency Service at the University of Missouri Veterinary Health Center Small Animal Hospital for generalized pain and lethargy. At presentation, the dog showed severe cervical spinal pain and thoracic limb deficits consistent with a multifocal neuroanatomic localization. Magnetic resonance imaging of the cervical spine revealed T2 and T1 postcontrast intense signal extending from the level of the medulla through C5 most marked in the caudal brainstem and cranial cervical spinal cord. The suspected diagnosis was severe meningoencephalomyelitis and secondary edema. Analysis of cerebrospinal fluid (CSF) collected from the cerebellomedullary cistern revealed a marked mixed pleocytosis with intralesional structures morphologically consistent with Mycobacterium sp. Standard DNA PCR assay performed on the CSF yielded the presence of Mycobacterium haemophilum. To the authors' knowledge, this is the first reported case of CNS mycobacteriosis diagnosed on CSF analysis in a dog.

Exosomal TAR DNA binding protein 43 profile in canine model of amyotrophic lateral sclerosis: a preliminary study in developing blood-based biomarker for neurodegenerative diseases.

OBJECTIVE: Blood-based biomarkers provide a crucial information in the progress of neurodegenerative diseases with a minimally invasive sampling method. Validated blood-based biomarker application in people with amyotrophic lateral sclerosis would derive numerous benefits. Canine degenerative myelopathy is a naturally occurring animal disease model to study the biology of human amyotrophic lateral sclerosis. Serum derived exosomes are potential carriers for cell-specific cargoes making them ideal venue to study biomarkers for a variety of diseases and biological processes. This study assessed the exosomal proteins that may be assigned as surrogate biomarker that may reflect biochemical changes in the central nervous system. METHODS: Exosomes were isolated from canine serum using commercial exosome isolation reagents. Exosomes target proteins contents were analyzed by the Western blotting method. RESULTS: The profiles of potential biomarker candidates in spinal cord homogenate and that of serum-derived exosomes were found elevated in dogs with degenerative myelopathy as compared to control subjects. CONCLUSIONS: Serum-derived exosomal biomolecules can serve as surrogate biomarkers in neurodegenerative diseases.KEY MESSAGESA canine with degenerative myelopathy can serve as a model animal to study human amyotrophic lateral sclerosis.Serum-derived exosomes contain Transactive Response DNA Binding Protein 43 (TDP-43), a potential biomarker candidate.The levels of spinal cord TDP-43 proteins and that of serum-derived exosomes exhibited similar profiling. Therefore, serum derived exosomes may be used as a venue for establishing blood-based biomarkers for neurodegenerative diseases.

Novel Homozygous ADAMTS2 Variants and Associated Disease Phenotypes in Dogs with Dermatosparactic Ehlers-Danlos Syndrome.

Tissue fragility, skin hyperextensibility and joint hypermobility are defining characteristics of Ehlers-Danlos syndrome (EDS). Human EDS is subclassified into fourteen types including dermatosparactic EDS, characterized by extreme skin fragility and caused by biallelic ADAMTS2 mutations. We report two novel, ADAMTS2 variants in DNA from EDS-affected dogs. Separate whole-genome sequences from a Pit Bull Terrier and an Alapaha Blue Blood Bulldog each contained a rare, homozygous variant (11:2280117delC, CanFam3.1), predicted to produce a frameshift in the transcript from the first coding ADAMTS2 exon (c.10delC) and a severely truncated protein product, p.(Pro4ArgfsTer175). The clinical features of these dogs and 4 others with the same homozygous deletion included multifocal wounds, atrophic scars, joint hypermobility, narrowed palpebral fissures, skin hyperextensibility, and joint-associated swellings. Due to severe skin fragility, the owners of all 6 dogs elected euthanasia before the dogs reached 13 weeks of age. Cross sections of collagen fibrils in post-mortem dermal tissues from 2 of these dogs showed hieroglyphic-like figures similar to those from cases of severe dermatosparaxis in other species. The whole-genome sequence from an adult Catahoula Leopard Dog contained a homozygous ADAMTS2 missense mutation, [11:2491238G>A; p.(Arg966His)]. This dog exhibited multifocal wounds, atrophic scars, and joint hypermobility, but has survived for at least 9 years. This report expands the spectrum of clinical features of the canine dermatosparactic subtype of EDS and illustrates the potential utility of subclassifying canine EDS by the identity of gene harboring the causal variant.

Electrical Impedance Myography in Dogs With Degenerative Myelopathy.

Canine degenerative myelopathy (DM) leads to disuse and neurogenic muscle atrophy. Currently there is a lack of non-invasive quantitative measures of muscle health in dogs with DM. Muscle pathology has been previously quantified in other disorders using the technique of electrical impedance myography (EIM) but it has not been reported for DM. The objective of this study was to compare EIM between DM-affected and similar aged healthy dogs as well as assess EIM changes over time in DM-affected dogs. Multifrequency EIM was performed on DM affected dogs at baseline and during disease progression and on age-matched healthy dogs. Muscles evaluated in the pelvic limbs included the craniotibialis, gastrocnemius, gracilis, sartorius, and biceps femoris. The 100 kHz phase angle was extracted from the full frequency set for analysis. Phase values were lower in DM dogs as compared to healthy controls. Specifically, phase of the gastrocnemius was lower on the left (θ = 7.69, 13.06; p =0.002) and right (θ= 6.11, 11.72; p = 0.001) in DM vs. control dogs, respectively. The mean phase value of all measured muscles was also lower on the left (θ = 9.24, 11.62; p = 0.012) and right (θ = 9.18, 11.72; p = 0.021). Other individual muscles measured did not reach statistical significance, although values were consistently lower in DM-affected dogs. With disease progression, downward trends in phase values were detected in DM-affected dogs when monitored serially over time. This study demonstrates that EIM 100 kHz phase values are sensitive to muscle pathology in DM and that phase values are decreased in dogs with DM. Measurements from the gastrocnemius muscle show the greatest differences from similar aged healthy dogs suggesting it may be the preferred muscle for future EIM studies.

Characterization of neurological disease progression in a canine model of CLN5 neuronal ceroid lipofuscinosis.

Golden Retriever dogs with a frameshift variant in CLN5 (c.934_935delAG) suffer from a progressive neurodegenerative disorder analogous to the CLN5 form of neuronal ceroid lipofuscinosis (NCL). Five littermate puppies homozygous for the deletion allele were identified prior to the onset of disease signs. Studies were performed to characterize the onset and progression of the disease in these dogs. Neurological signs that included restlessness, unwillingness to cooperate with the handlers, and proprioceptive deficits first became apparent at approximately 12 months of age. The neurological signs progressed over time and by 21 to 23 months of age included general proprioceptive ataxia, menace response deficits, aggressive behaviors, cerebellar ataxia, intention tremors, decreased visual tracking, seizures, cognitive decline, and impaired prehension. Due to the severity of these signs, the dogs were euthanized between 21 and 23 months of age. Magnetic resonance imaging revealed pronounced progressive global brain atrophy with a more than sevenfold increase in the volume of the ventricular system between 9.5 and 22.5 months of age. Accompanying this atrophy were pronounced accumulations of autofluorescent inclusions throughout the brain and spinal cord. Ultrastructurally, the contents of these inclusions were found to consist primarily of membrane-like aggregates. Inclusions with similar fluorescence properties were present in cardiac muscle. Similar to other forms of NCL, the affected dogs had low plasma carnitine concentrations, suggesting impaired carnitine biosynthesis. These data on disease progression will be useful in future studies using the canine model for therapeutic intervention studies.

Epidural myelolipoma in a Silken Windhound.

A 12-year-old female spayed, Silken Windhound dog was presented with a 3-month history of lethargy and cervical and lumbosacral spinal pain. No significant abnormalities were noted on CBC or serum biochemical assays. Magnetic resonance imaging of the spine demonstrated a soft tissue mass within the ventral and right epidural space at the level of the L7 vertebra. During surgery, a pale brown mass was identified within the epidural fat. Cytologic and histopathologic examinations demonstrated that the mass was composed of adipose tissue and hematopoietic elements, consistent with a myelolipoma. The lumbosacral spinal pain resolved after surgery. Epidural myelolipomas are rarely reported in the human and veterinary literature.

Electrical impedance myography in healthy dogs: Normative values, repeatability, and the impact of age.

Convenient tools to assess canine skeletal muscle health would be useful for a variety of applications, including standard veterinary assessments of dog fitness, as well as studies of muscle deterioration due to age or disease. One technology that can be applied conveniently to awake dogs with minimal restraint is electrical impedance myography (EIM). In EIM, a weak electrical current is applied via surface electrodes to a muscle of interest and consequent impedance characteristics of the muscle are obtained, providing insight into muscle condition and composition. In this study, we assessed a total of 73 dogs (42 males and 31 females), of varied neutering status and breed, ages 0.6 to 13.5 years. We identified age-dependent reference values for the 100 kHz phase value in three pelvic limb muscles, caudal sartorius, cranial tibial, and gastrocnemius. While phase values were generally higher in males than females, the difference did not reach significance. In general, values declined on average with age at about 0.5 degrees/year, but with the decline being most substantial in the oldest dogs. Limited reproducibility assessment of the technique suggested good repeatability with variation in values between measurements being under 5%. These results show that EIM has the potential for the assessment of canine muscle health and may find value in aging muscle research.

Brain diffusion tensor imaging in dogs with degenerative myelopathy.

BACKGROUND: Degenerative myelopathy (DM) in dogs shares similarities with superoxide dismutase 1-associated human amyotrophic lateral sclerosis (ALS). Brain microstructural lesions are quantified using diffusion tensor imaging (DTI) in ALS patients. OBJECTIVE: Characterize brain neurodegenerative changes in DM-affected dogs using DTI. ANIMALS: Sixteen DM-affected and 8 control dogs. METHODS: Prospective observational study. Brain DTI was performed at baseline and every 3 months on DM-affected dogs and compared to controls. Fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity were calculated on specified regions of interest. Gait scores (0, normal to 14, tetraplegia) were assigned at each scan. Diffusion tensor imaging values in DM-affected dogs were compared to controls, gait scores, and evaluated over time. RESULTS: Mean age was 5.7 years (SD 3.2) in controls and 9.7 years (SD 1.4) in DM-affected dogs. In DM-affected dogs, mean baseline gait score was 4 (SD 1), and mean score change from baseline to last scan was 4.82 (SD 2.67). Nine dogs had ≤3 scans; 7 had >3 scans. Accounting for age, no differences in DTI indices were identified for any brain or proximal spinal cord regions between DM-affected dogs and controls (P > .05). Diffusion tensor imaging values poorly correlated with gait scores (R2 < .2). No significant changes were identified in diffusion indices over time (P > .05). CONCLUSIONS AND CLINICAL IMPORTANCE: Diffusion tensor imaging indices did not differentiate DM-affected from control dogs, detect longitudinal changes, or differentiate disease severity. Findings do not yet support brain DTI as an imaging biomarker.

Skeletal Manifestations of Heritable Disproportionate Dwarfism in Cats as Determined by Radiography and Magnetic Resonance Imaging.

OBJECTIVE: The aim of this study was to characterize the radiographic alignment of thoracic and pelvic limbs and evaluate for intervertebral disc disease in cats with feline disproportionate dwarfism (FDD). STUDY DESIGN: Observational cross-sectional study. Radiographic joint orientation angles were measured in 10 thoracic and pelvic limbs from 5 FDD cats and compared with those angles measured in 24 thoracic limbs and 100 pelvic limbs from skeletally normal cats. Magnetic resonance imaging of the spine was performed in 2 FDD cats for the evaluation of pathology of the intervertebral discs or vertebrae. RESULTS: All limbs from FDD cats possessed deformities. FDD humeri demonstrated procurvatum proximally, and recurvatum distally in the sagittal plane, but showed no difference in the frontal plane. FDD radii possessed excessive recurvatum proximally, and procurvatum distally in the sagittal plane, and varus proximally and valgus distally in the frontal plane. Whereas no torsion was discernible in the humeri, all radii had external torsion. In the frontal plane, FDD femurs exhibited varus both proximally and distally whereas the tibia possessed proximal valgus and distal varus. No torsion in the pelvic limbs was observed. No spinal pathology was detected in the FDD cats included in the original study. CONCLUSION: Feline disproportionate dwarfism results in significant appendicular deformity in all limbs. The incidence of intervertebral disc degeneration in FDD cats is inconclusive.

A CTSA One Health Alliance (COHA) survey of clinical trial infrastructure in North American veterinary institutions.

While a necessary step toward enhancing rigor and reproducibility of veterinary clinical trials conducted on the translational spectrum includes understanding the current state of the field, no broad assessment of existing veterinary clinical trial resources has been previously conducted. Funded by a CTSA One Health Alliance (COHA) pilot award, the goal of this project was to conduct an electronic survey of North American Veterinary Colleges regarding practices in veterinary clinical trial review, approval, conduct, and support in order to identify opportunities to leverage existing resources and develop new ones to enhance the impact of veterinary and translational health research.A total of 30 institutions were invited to participate in the survey and the survey response rate was 73 %. The most common source of funding noted for veterinary clinical research was industry (33 %); however, respondents reported that only 5 % (3.7-11.0) of studies were FDA-regulated. Respondents indicated that most studies (80 %); conducted at their institution were single site studies. Study review and approval involved the IACUC either solely, or in combination with a hospital review board, at 95.5 % of institutions. Workforce training related to clinical research best practices was variable across institutions. Opportunities were identified to strengthen infrastructure through harmonization of clinical research review and approval practices. This might naturally lead to expansion of multi-site studies. Based on respondent feedback, future workforce development initiatives might center on training in the specifics of conducting FDA-sponsored research, Good Clinical Practice (GCP), clinical study budget design, grants management, adverse event reporting, study monitoring and use of electronic data capture platforms.

Effect of an advanced degree on veterinary technician salary in the United States.

OBJECTIVE: To compare the salaries of certified veterinary technicians with an associate's degree to those with a bachelor's or a master's degree. SAMPLE: 1,289 credentialed veterinary technicians in the United States. PROCEDURES: Credentialed veterinary technicians were asked to complete an online questionnaire in the fall of 2018 administered by veterinary technician associations and accredited veterinary technology institutions. Additional links to the survey were published on various social media sources. RESULTS: Mean ± SD hourly pay rate for all respondents was $20.24 ± 6.33. Weighted mean pay rate for those with an associate's degree was $19.93, with a bachelor's degree was $22.37, and with a master's degree was $27.55. Factors positively influencing veterinary technician salary were years of experience as a licensed veterinary technician, level of education, gender, veterinary technician specialist certification, and years worked for current employer. CONCLUSIONS AND CLINICAL RELEVANCE: Years of experience as a licensed veterinary technician, level of education, gender, veterinary technician specialist certification, and years with current employer affected pay rate for credentialed veterinary technicians in the United States.

Optimizing the Translational Value of Mouse Models of ALS for Dysphagia Therapeutic Discovery.

The goal of this study was to compare dysphagia phenotypes in low and high copy number (LCN and HCN) transgenic superoxide dismutase 1 (SOD1) mouse models of ALS to accelerate the discovery of novel and effective treatments for dysphagia and early amyotrophic lateral sclerosis (ALS) diagnosis. Clinicopathological features of dysphagia were characterized in individual transgenic mice and age-matched controls utilizing videofluoroscopy in conjunction with postmortem assays of the tongue and hypoglossal nucleus. Quantitative PCR accurately differentiated HCN-SOD1 and LCN-SOD1 mice and nontransgenic controls. All HCN-SOD1 mice developed stereotypical paralysis in both hindlimbs. In contrast, LCN-SOD1 mice displayed wide variability in fore- and hindlimb involvement. Lick rate, swallow rate, inter-swallow interval, and pharyngeal transit time were significantly altered in both HCN-SOD1 and LCN-SOD1 mice compared to controls. Tongue weight, tongue dorsum surface area, total tongue length, and caudal tongue length were significantly reduced only in the LCN-SOD1 mice compared to age-matched controls. LCN-SOD1 mice with lower body weights had smaller/lighter weight tongues, and those with forelimb paralysis and slower lick rates died at a younger age. LCN-SOD1 mice had a 32% loss of hypoglossal neurons, which differed significantly when compared to age-matched control mice. These novel findings for LCN-SOD1 mice are congruent with reported dysphagia and associated tongue atrophy and hypoglossal nucleus pathology in human ALS patients, thus highlighting the translational potential of this mouse model in ALS research.

Lumbar spinal cord microglia exhibited increased activation in aging dogs compared with young adult dogs.

Altered microglia function contributes to loss of CNS homeostasis during aging in the brain. Few studies have evaluated age-related alterations in spinal cord microglia. We previously demonstrated that lumbar spinal cord microglial expression of inducible nitric oxide synthase (iNOS) was equivalent between aging, neurologically normal dogs and dogs with canine degenerative myelopathy (Toedebusch et al. 2018, Mol Cell Neurosci. 88, 148-157). This unexpected finding suggested that microglia in aging spinal cord have a pro-inflammatory polarization. In this study, we reexamined our microglial results (Toedebusch et al. 2018, Mol Cell Neurosci. 88, 148-157) within the context of aging rather than disease by comparing microglia in aging versus young adult dogs. For both aging and young adult dogs, the density of microglia was significantly higher closest to the motor neuron cell body. However, there was no difference in densities between aging versus young adult dogs at all distances except for the furthest distance analyzed. The number of motor neurons with polarized microglia was higher in aging dogs; yet, the density per motor neuron of arginase-1-expressing microglia was reduced in aging dogs compared with young adult dogs. Finally, aging dogs had increased steady-state mRNA levels for genes consistent with activated microglia compared with young adult dogs. However, altered mRNA levels were limited to the lumbar spinal cord. These data suggested that aging dog spinal cord microglia exhibit regional immunophenotypic differences, which may render lumbar motor neurons more susceptible to age-related pathological insults.

Comparison of intranasal versus intravenous midazolam for management of status epilepticus in dogs: A multi-center randomized parallel group clinical study.

BACKGROUND: The intranasal (IN) route for rapid drug administration in patients with brain disorders, including status epilepticus, has been investigated. Status epilepticus is an emergency, and the IN route offers a valuable alternative to other routes, especially when these fail. OBJECTIVES: To compare IN versus IV midazolam (MDZ) at the same dosage (0.2 mg/kg) for controlling status epilepticus in dogs. ANIMALS: Client-owned dogs (n = 44) with idiopathic epilepsy, structural epilepsy, or epilepsy of unknown origin manifesting as status epilepticus. METHODS: Randomized parallel group clinical trial. Patients were randomly allocated to the IN-MDZ (n = 21) or IV-MDZ (n = 23) group. Number of successfully treated cases (defined as seizure cessation within 5 minutes and lasting for ≥10 minutes), seizure cessation time, and adverse effects were recorded. Comparisons were performed using the Fisher's exact and Wilcoxon rank sum tests with statistical significance set at α < .05. RESULTS: IN-MDZ and IV-MDZ successfully stopped status epilepticus in 76% and 61% of cases, respectively (P = .34). The median seizure cessation time was 33 and 64 seconds for IN-MDZ and IV-MDZ, respectively (P = .63). When the time to place an IV catheter was taken into account, IN-MDZ (100 seconds) was superior (P = .04) to IV-MDZ (270 seconds). Sedation and ataxia were seen in 88% and 79% of the dogs treated with IN-MDZ and IV-MDZ, respectively. CONCLUSIONS AND CLINICAL IMPORTANCE: Both routes are quick, safe, and effective for controlling status epilepticus. However, the IN route demonstrated superiority when the time needed to place an IV catheter was taken into account.

The Role of Glia in Canine Degenerative Myelopathy: Relevance to Human Amyotrophic Lateral Sclerosis.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive degeneration of motor neurons and grim prognosis. Over the last decade, studies on neurodegenerative diseases pointed on the role of glia in supporting the proper function of neurons. Particularly, oligodendrocytes were shown to be essential through myelin production and supplying axons with energy metabolites via monocarboxylate transporters (MCT). We have used dogs with naturally occurring degenerative myelopathy (DM) which closely resembles features observed in human ALS. We have performed two types of analysis of spinal cord tissue samples: histology and molecular analysis. Histology included samples collected from dogs that succumbed to the DM at different disease stages, which were compared to age-matched controls as well as put in the context of young spinal cords. Molecular analysis was performed on spinal cords with advanced DM and age-matched samples and included real-time PCR analysis of selected gene products related to the function of neurons, oligodendrocytes, myelin, and MCT. Demyelination has been detected in dogs with DM through loss of eriochrome staining and decreased expression of genes related to myelin including MBP, Olig1, and Olig2. The prominent reduction of MCT1 and MCT2 and increased MCT4 expression is indicative of disturbed energy supply to neurons. While Rbfox3 expression was not altered, the ChAT production was negatively affected. DM in dogs reproduces main features of human ALS including loss of motor neurons, dysregulation of energy supply to neurons, and loss of myelin, and as such is an ideal model system for highly translational studies on therapeutic approaches for ALS.

Protein disulphide isomerase is associated with mutant SOD1 in canine degenerative myelopathy.

Canine degenerative myelopathy (DM) is a fatal neurodegenerative disorder prevalent in the canine population. It may represent a unique, naturally occurring disease model for human amyotrophic lateral sclerosis (ALS) because of similar clinical signs and association with superoxide dismutase 1 gene (SOD1) mutations. Misfolded SOD1 aggregates and endoplasmic reticulum (ER) stress are major pathophysiological features associated with ALS. Interestingly, an ER foldase, protein disulphide isomerase (PDI) is upregulated during ALS and it co-localizes with SOD1 inclusions in ALS patient tissues. Furthermore, mutations in the gene encoding PDI were recently associated with ALS. Given the genetic similarity between DM and ALS, we investigated whether ER stress and PDI were associated with DM. Protein extracts from spinal cord tissue of DM-affected dogs bearing a SOD1 mutation were examined for ER stress by western blotting. Immunohistochemical staining was also carried out to examine co-localization between endogenous PDI and SOD1 inclusions in spinal cord tissues of dogs affected with DM. PDI and CHOP, the proapoptotic protein induced during ER stress, were significantly upregulated in DM-affected dogs compared with controls. Furthermore, PDI co-localized with intracellular SOD1 aggregates in DM-affected dogs in all motor neurons examined, indicating that PDI may be a cellular defence mechanism against SOD1 misfolding in DM. Our results imply that ER stress is induced in DM-affected dogs; hence, it is a common pathological mechanism associated with both ALS and DM. The possibility that PDI may be a therapeutic target to inhibit SOD1 aggregation in DM dogs is also raised by this study.

Arginase-1 expressing microglia in close proximity to motor neurons were increased early in disease progression in canine degenerative myelopathy, a model of amyotrophic lateral sclerosis.

Toxicity within superoxide dismutase-1 (SOD1)-associated familial amyotrophic lateral sclerosis (ALS) is non-cell autonomous with direct contribution from microglia. Microglia exhibit variable expression of neuroprotective and neurotoxic molecules throughout disease progression. The mechanisms regulating microglial phenotype within ALS are not well understood. This work presents a first study to examine the specific microglial phenotypic response in close association to motor neurons in a naturally occurring disease model of ALS, canine degenerative myelopathy (DM). Microglia closely associated with motor neurons were increased in all stages of DM progression, although only DM Late reached statistical significance. Furthermore, the number of arginase-1 expressing microglia per motor neuron were significantly increased in early stages of DM, whereas the number of inducible nitric oxide synthase (iNOS)-expressing microglia per motor neuron was indistinguishable from aged controls at all stages of disease. Fractalkine, a chemotactic molecule for microglia, was expressed in motor neurons, and the fractalkine receptor was specifically localized to microglia. However, we found no correlation between microglial response and lumbar spinal cord fractalkine levels. Taken together, these data suggest that arginase-1-expressing microglia are recruited to the motor neuron early in DM disease through a fractalkine-independent mechanism.