Masticatory Myositis Research Articles

Idiopathic Polymyositis Showing Nonspecific Clinical Signs that Mimicked Masticatory Myositis in a Dog

Idiopathic Polymyositis Showing Nonspecific Clinical Signs that Mimicked Masticatory Myositis in a Dog

Novel Management of Masticatory Myositis in Three Dogs with a Selective Janus Kinase (JAK-1) Inhibitor.

Masticatory myositis (MM) is an inflammatory myopathy reported in dogs and is characterized by inflammation of the masticatory muscles (temporalis, masseter, and pterygoid muscles). Immunosuppressive therapy is the current recommended treatment for MM and may involve glucocorticoids, cyclosporine, azathioprine, mycophenolate mofetil, leflunomide, or a combination of these treatments that are slowly tapered to the lowest effective dose. However, side effects from multimodal medical therapy and complications associated with MM relapses have been reported. The purpose of this case series was to report oclacitinib as a treatment alternative to traditional medical management of MM. The intent of this alternative is to manage side effects from glucocorticoid use. Oclacitinib (1mg/kg per os q12h) was used solely for treatment of MM in three dogs. The dogs were followed up to >6 months after oclacitinib administration. An increase in oral range of motion, as determined by gape angle, was noted in all three dogs. However, a corresponding drop in antibody titers (2M fiber) did not occur. All dogs showed improvement in overall clinical management of MM, side effects from glucocorticoids, and clinical signs related to chronic prednisone use. Larger controlled trials with consistent measurements (interincisal distance, gape angle) and 2M fiber antibody titers are indicated to further assess validation of oclacitinib treatment of MM. The clinical outcome of all dogs was considered successful.

Low-intensity pulsed ultrasound in the treatment of masticatory myositis and temporomandibular joint synovitis: A clinical trial

BackgroundLow-intensity pulsed ultrasound (LIPUS) is a non-invasive physical stimulation application for the therapy of articular cartilage injury. This study aimed to explore the therapeutic effects of low-intensity pulsed ultrasound in treating masticatory myositis and synovitis in temporomandibular joint disorders and to establish an evaluation system to evaluate the clinical efficacy. MethodsTMD patients who met the inclusion criteria in the temporomandibular joint clinic of the affiliated Stomatological Hospital of Chongqing Medical University from April 3, 2021, to December 2021 were selected. Before the start and after 7 days of LIPUS treatment, the Fricton temporomandibular joint disorder index, Visual Analog Scale (VAS), and Pressure Difference of Precision Manometer (PD) were measured. A paired t-test was used to compare the values of the Fricton index, VAS, and PD before and after treatment in each group. One-way ANOVA analysis of variance was used to compare the differences between groups. ResultsAfter one week of LIPUS treatment, the PI, DI and CMI of the Fricton index in the masticatory myositis (PI: P < 0.001; CMI: P < 0.001; DI: P = 0.2641, ns) and the synovitis group (DI: P < 0.001; CMI: P < 0.001, PI: P = 0.9729, ns) significantly decreased. The VAS of the masticatory myositis group and the synovitis group were significantly reduced (P < 0.001). The PD between the affected and healthy sides of the masticatory myositis group and the synovitis group was significantly reduced (P < 0.001), and the reduction was more evident in the M group. ConclusionsLIPUS is effective in pain relief in patients with masticatory myositis and joint synovitis, meanwhile, masticatory myositis was more sensitive to LIPUS. A new comprehensive clinical efficacy evaluation system which includes PV, FI, and VAS was created to better 2 diagnose masticatory myositis and joint synovitis.

Neurological Disorders in Pug Dogs: a Retrospective Study of 285 Cases (2013 – 2020) from a Single Referral Hospital in the United Kingdom

Pugs are commonly affected by neurological disorders and this retrospective observational study aims to describe what pathologies were more commonly diagnosed, their diagnostic approach and clinical features. This study was performed in a single referral hospital in the United Kingdom (UK). Medical records of pugs referred to the Neurology &amp; Neurosurgery department from 2013 to 2020 were retrieved. Signalment, presenting complaint, presence of pain at neurological examination and diagnostic tests were recorded. Final diagnosis was classified as: encephalopathies, myelopathies or peripheral nervous system (PNS) disease. Descriptive and univariate statistical analysis were performed. A total of 285 records were included in the study. The most common presenting complaints were: ambulatory paraparesis (27.6%), seizures (20.3%), ataxia (16.4%), spinal pain (10.1%) and vestibular signs (5.6%). Myelopathies were diagnosed in 64.7% of pugs, while encephalopathies and PNS disease in 29.7% and 5.3% of pugs respectively. Different types of intervertebral disc diseases (IVDDs; 44.3%), spinal arachnoid diverticulum (SAD; 22.2%) and vertebral malformations (VMs; 18.9%) were the most prevalent myelopathies. Idiopathic epilepsy (IE; 44.7%) and meningoencephalitis of unknown aetiology (MUA; 29.4%) were the most common encephalopathies. Peripheral vestibular syndrome (60%) and masticatory muscle myositis (20%) were the most prevalent PNS diseases. Pugs with IVDDs were more likely to be painful than pugs diagnosed with SAD and VMs. In this study, IVDDs, SAD and VMs were the most represented myelopathies, while IE and MUA the most prevalent encephalopathies. SAD and VMs were found to be non-painful myelopathies, as opposed to IVDDs being painful. These results may be used as a guide reflecting the prevalence of neurological diseases in a larger population of pugs.

Systemic lupus erythematosus in a dog treated for temporomandibular disorder – a case report

A 7-year-old, castrated male, Dachshund dog initially presented with locked-jaw syndrome. Computed tomography and magnetic resonance imaging indicated bilateral lymphadenopathy, but no skeletal or joint disorder was suspected. The dog showed no evidence of masticatory muscle myositis in the masticatory muscle antibody test and histopathologic examination, indicating non-infectious inflammation. Temporomandibular disorder due to immune-mediated disease was suspected, and the symptoms improved following prednisolone treatment. One year later, the dog was referred with multiple joint swellings and fever. Based on radiographic findings, synovial fluid analysis, and positive results of the antinuclear antibody test, systemic lupus erythematosus was diagnosed. The previous temporomandibular disorder might have been caused by systemic lupus erythematosus showing typical characteristics of recurrence and instability of various musculoskeletal systems. The symptoms were also relieved by glucocorticoid treatment. This report describes a case of systemic lupus erythematosus in a dog that was previously treated for temporomandibular disease, implying that systemic lupus erythematosus might be a cause of temporomandibular disorder or the two diseases might be associated in dogs.

Masseter myodegeneration in the horse: Suggested approach to diagnosis and treatment

SummaryA descriptive case report of the management of a miniature pony presenting to a UK equine veterinary hospital with marked trismus and increased masseter muscle size. Diagnosis of masseter myodegeneration (MM) was aided by the use of computed tomography and excisional biopsy. Hyperlipaemia was diagnosed as a sequelae of MM. Treatment included nonsteroidal anti‐inflammatories, parenteral nutrition and fluid therapy in addition to supportive care. The gelding was discharged from the hospital 30 days after admission, having made a full recovery. MM in the horse is a rare condition that appears to be physiologically distinct from canine masticatory muscle myositis which is primarily immune mediated.

Generalised idiopathic polymyositis mimicking masticatory myositis in a dog

AbstractMasticatory myositis (MM) and generalised idiopathic polymyositis (gIPM) are the most common immune‐mediated myositis in dogs. In humans, the diagnosis and classification of myositis have continuously evolved over the past few decades with the combination of histopathological and immunohistochemical evaluation alongside the identification of myositis‐specific autoantibodies (MSAs). In dogs, however, MSAs have only been described in MM and breeds such as Newfoundland and Boxer. We report a case of a dog that presented with sub‐acute pain when chewing and exophthalmos, followed by chronic progressive masticatory muscle atrophy and enophthalmos. Clinical signs and electromyography were primarily consistent with MM, but serological autoantibodies against type 2M myofibres were negative. Creatine kinase activity, histological and immunohistochemical examination of the temporal and triceps brachii muscles and negative infectious disease tests were consistent with gIPM. This atypical case highlights the requirement for multiple muscle biopsies and appeals for extended immunohistochemical studies in canine myositis.

Dexamethasone Can Be Safely and Effectively Used for Treatment of Masticatory Muscle Myositis in Dogs

Dexamethasone is the glucocorticoid of choice in many human inflammatory and immune-mediated conditions, given its reported effectiveness and limited side effect profile. In veterinary medicine, the glucocorticoid of choice is prednisone, however the safety of longer-term use of dexamethasone has not previously been studied. The aim of this study was to evaluate the safety, effectiveness and side effects of dexamethasone use as the glucocorticoid treatment for masticatory muscle myositis in dogs - an immune-mediated inflammatory condition. 93% of dogs showed a clinical improvement within two weeks of treatment, and 100% by ten weeks. 35% of dogs showed adverse reactions, however these were all mild and resolved with tapering of the dexamethasone dose. In conclusion, dexamethasone can be safely and effectively used for the treatment of masticatory muscle myositis in dogs, and should be considered for use in these cases, either alone or alongside additional immunosuppressive medications. Side effects are mild and resolve with tapering of the dexamethasone dose.

Management of presumptive canine permethrin toxicosis using intravenous lipid emulsion as an adjunctive therapy

A seven-month-old Cavalier King Charles spaniel presented with generalised, coarse muscle tremors that progressed to seizure activity, after observed ingestion (licking) of a cleaning product containing permethrin. At the time...

Treatment Outcome of 22 Dogs With Masticatory Muscle Myositis (1999-2015)

Medical records of dogs diagnosed with masticatory muscle myositis (MMM) at Ryan Veterinary Hospital of the University of Pennsylvania during a period of 17 years (from 1999 to 2015) were reviewed. Twenty-two dogs were included in this retrospective case series study. Immunosuppressive doses of prednisone were prescribed to all dogs. Twenty dogs had full recovery of masticatory function. The mean (SD) improvement in the vertical mandibular range of motion (vmROM) was 5.3 (3.1) cm during the first 4 weeks of treatment (weeks 1-4) and 2.8 (2.2) cm during the subsequent 8 weeks (weeks 5-12). The vmROM continued to improve for several more months. Six dogs had a relapse, but the clinical signs were more severe in dogs when no longer receiving prednisone compared to dogs still on prednisone at the time of relapse. When diagnosed and treated appropriately, MMM has a good prognosis with relatively quick return to masticatory function. Early discontinuation of prednisone therapy should be avoided. Approximately 1 year of therapy is recommended prior to discontinuing the medication. Educating the client about how to perform muscle palpation, determine vmROM at home, recognize signs of pain, and notice behavioral changes may help in the early detection of relapses.

Canine babesiosis

The causative agents of canine babesiosis are Babesia canis and B. gibsoni which are transmitted by various hard tick species and blood transfusions. In the hyperacute form of the disease hypothermia, shock, severe metabolic acidosis and disseminated intravascular coagulation usually precede the death of the dog occuring in less than 24 hours. Severe anemia, icterus, splenomegaly and peripheral lymphadenopathy characterize the acute form of the disease. Intermittent fever and progressive loss of body weight may be noticed in the chronic form of babesiosis, while its many atypical clinical manifestations (e.g. ascites, gastrointestinal signs, CNS disease, subcutaneous edema, masticatory myositis) often cause diagnostic confusion. The organism detection on RBC in thin blood smears made from the buffy coat is a must for definitive diagnosis. The IFA test is a good choice for screening large numbers of dogs for detecting the asymptomatic carriers. Complete parasitological cure can be obtained with imidocarb dipropionate, pentamidine isethionate or diminazene aceturate, while metronidazole and clindamycin have been recently suggested as good alternatives. Supportive care is considered crucial for the survival of the severely affected animals. While effective tick control is the mainstay of prevention, doxycycline and imidocarb may also play a significant role to that goal. The effectiveness of a killed vaccine is still a matter of controversy.

Chronic or atrophie masticatory myositis in the dog. A report of two spontaneous cases

Two young adult dogs (case 1: German wirehaired pointer male, case 2: mongrel female) were admitted to our Clinic because of a progressive, bilateral and symmetrical atrophy of the masticatory muscles, that was most obvious in the temporal muscles. No signs of mandibular dysfunction were detected in both animals. The clinical diagnosis of chronic or atrophic myositis was confirmed by the histopathology of temporal muscle biopsies, which revealed the typical of the disease lesions, such as myofiber degeneration, regeneration and atrophy, interstitial or perivascular cellular infiltrates, chiefly of lymphocytes and plasma cells plus perimysial fibrosis. Temporal muscle electromyography, done only in case 1, showed abnormal spontaneous activity indicating myositis. The use of prednisolone at immunosuppressive doses, with or without azathioprine, not only stopped the progression of the disease but resulted in a partial restoration of the masticatory muscle mass.

Masticatory muscle myositis in Rottweiler – Case report

The clinical presentation of masticatory muscle myositis (MMM) in dogs reflects focal inflammatory myopathy of the muscles of mastication, while limb muscles are spared. Signs range from acute swelling of the temporalis and masseter muscles, restricted jaw movement, jaw pain, and exophthalmus, to muscle atrophy. The diagnosis is confirmed by a muscle biopsy. Early diagnosis and therapy with immunosuppressive doses of corticosteroids usually yields a good prognosis. This paper reports a case of MMM in a Rottweiler.

Clinical features of idiopathic inflammatory polymyopathy in the Hungarian Vizsla.

BackgroundA retrospective study of the clinicopathological features of presumed and confirmed cases of idiopathic inflammatory polymyopathy in the Hungarian Vizsla dog and guidelines for breeding.Results369 medical records were reviewed (1992–2013) and 77 Hungarian Vizslas were identified with a case history consistent with idiopathic inflammatory polymyopathy. Inclusion criteria were: group 1 (confirmed diagnosis); histopathology and clinical findings compatible with an inflammatory polymyopathy and group 2 (probable diagnosis); clinical findings compatible with a polymyopathy including dysphagia, sialorrhea, temporal muscle atrophy, elevated serum creatine kinase (CK) activity, and sufficient clinical history to suggest that other neuromuscular disorders could be ruled out. Some group 2 dogs had muscle biopsy, which suggested muscle disease but did not reveal an inflammatory process. The mean age of onset was 2.4 years; male dogs were slightly overrepresented. Common presenting signs were dysphagia, sialorrhea, masticatory muscle atrophy, and regurgitation. Common muscle histopathological findings included degenerative and regenerative changes, with multifocal mononuclear cell infiltration with lymphoplasmacytic myositis of variable severity. A positive response to immunosuppressive treatment supported an immune-mediated aetiology. The mean age at death and survival time were 6.4 and 3.9 years, respectively. Recurrence of clinical signs and aspiration pneumonia were common reasons for euthanasia.ConclusionsDiagnosis of Vizsla idiopathic inflammatory polymyopathy can be challenging due to lack of specific tests, however the presence of dysphagia, regurgitation and masticatory muscle atrophy in this breed with negative serological tests for masticatory muscle myositis and myasthenia gravis, along with muscle biopsies suggesting an inflammatory process, support the diagnosis. However, there is an urgent need for a more specific diagnostic test. The average of inbreeding coefficient (CoI) of 16.3% suggests an increased expression of a Dog Leukocyte Antigen Class II haplotype, leading to an increased disease risk. The prognosis remains guarded, as treatment can only manage the disease. Recurrence of clinical signs and perceived poor quality of life are the most common reasons for humane euthanasia.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-015-0408-7) contains supplementary material, which is available to authorized users.

Necrotizing and Eosinophilic Masticatory Myositis in Farmed Mink: a Preliminary Description

This report describes necrotizing and eosinophilic myositis affecting the masticatory muscles of a group of mink. Affected animals demonstrated sudden death with marked subcutaneous oedema over the dorsal head. The temporalis and masseter muscles were pale, swollen and friable. Histologic changes consisted of varying degrees of myodegeneration, myonecrosis and inflammation. Eosinophils were prominent in the inflammatory infiltrate. Similar to dogs, masticatory muscles in mink were found to contain unique type 2M fibres, suggesting a possible target for an immune response. Aerobic and anaerobic tissue cultures of the affected musculature revealed no significant pathogens. Histological and nutritional analyses were not typical of vitamin E/selenium deficiency. This case series supports the existence of a novel disease entity in mink with some features comparable with masticatory muscle myositis in dogs.

Masticatory Muscle Myositis in a Maltese Dog

초록·키워드 목차 오류제보하기 등록된 정보가 없습니다. #dog #masticatory muscle myositis #개 #저작근염 등록된 정보가 없습니다.

Masticatory Myositis in a Toy Poodle

Masticatory Myositis in a Toy Poodle

Use of MRI for the Early Diagnosis of Masticatory Muscle Myositis

The medical records of two dogs that were diagnosed with masticatory muscle myositis (MMM) were reviewed. The reported clinical signs included intense pain when opening the mouth and restricted jaw movement. MRI detected widespread, symmetrical, and inhomogeneously hyperintense areas in the masticatory muscle. Electromyography (EMG) demonstrated severe and spontaneous pathologic activity in the temporal and masseter muscles. With early therapeutic treatment, remission of symptoms occurred within 2 mo, and no relapses were observed for the subsequent 2 yr. The gold standard for the diagnosis of MMM is the 2M antibody test, but the purpose of this study was to evaluate the use of MRI as an accurate and efficient diagnostic tool for the initiation of early therapy for the treatment of muscle myositis.

I.I.4 Autoimmune muscle diseases in dogs and cats: Spontaneous models for evaluation of therapies?

Spontaneously occurring autoimmune muscle diseases such as polymyositis (PM) and myasthenia gravis (MG) commonly affect dogs and to a lesser extent cats. A typical myopathic clinical phenotype including weakness, muscle atrophy and stiffness occurs in PM, and focal or generalized muscle weakness without atrophy occurs in MG. As in humans, diagnosis of PM is confirmed by muscle biopsies and immunophenotyping of cellular infiltrates, and of MG by a positive acetylcholine receptor antibody titer. Species-specific features of MG include frequent spontaneous immune remissions in the dog and a high incidence of thymoma associated MG in cats. Dermatomyositis in dogs is breed-associated and infrequently diagnosed. Most recently, a myopathy similar to spontaneous inclusion body myositis (sIBM) was identified in the dog recapitulating both the degenerative and inflammatory aspects of the human disease. Focal forms of immune-mediated myositis also occur in dogs including the apparently species-specific masticatory muscle myositis with muscle specific autoantibodies, and focal forms limited to other muscle groups. As rodent models have been largely unsuccessful in translation of new therapies for muscle diseases to human patients, large animal models of human muscle diseases are growing in importance and may be more clinically relevant. As autoimmune muscle diseases in large animals become better described and classified, these models of immune-mediated muscle disease will take a prominent role for therapeutic trials alongside the well established models of canine dystrophin deficient muscular dystrophy, centronuclear myopathy and myotubular myopathy.

Role of serotonergic system in the pathogenesis of fibrosis in canine idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies are muscle diseases characterized by inflammation, necrosis, and fibrosis. The neurotransmitter serotonin (5-HT) has been shown to promote fibrosis in many tissues and organs by activating TGFβ-1 signaling. In this study, we evaluated the potential role of 5-HT in the pathogenesis of fibrosis in canine idiopathic inflammatory myopathies. Muscle biopsies from dogs affected by masticatory muscle myositis or polymyositis and from healthy dogs were processed for immunohistochemistry and Western blotting. The immunohistochemical analysis showed a strong expression of 5-HT in muscle tissues of affected dogs, whereas the amine was absent in the muscles of healthy dogs. Biochemical analysis showed increased expression levels of the selective 5-HT2A receptor in the muscle specimens of the most severely affected dogs versus controls. Further, increased phosphorylation levels of the TGFβ-1 signaling mediators SMAD2/3 and ERK1/2 were detected in tissue samples from affected dogs as compared to tissues from healthy dogs. Although further studies are needed, our findings highlight for the first time a potential role of 5-HT in the development of fibrosis in canine idiopathic inflammatory myopathies, thus supporting other evidence that 5-HT pro-fibrotic activity occurs via activation of TGFβ-1 signaling pathway.