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Neuromuscular diseases in animals

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This document discusses several neuromuscular disorders commonly seen in veterinary practice, including myasthenia gravis, laryngeal paralysis, inflammatory myopathies, and canine neosporosis. Myasthenia gravis is an autoimmune disease affecting the neuromuscular junction causing muscle weakness. Laryngeal paralysis results in difficulty breathing, coughing, and exercise intolerance due to impaired larynx movement. Inflammatory myopathies like polymyositis cause muscle inflammation, weakness, and high creatine kinase levels. Canine neosporosis is a protozoal infection that causes ascending paralysis, hindlimb weakness, and potentially death from paralysis or pneumonia.

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NEUROMUSCULAR DISORDERNEUROMUSCULAR DISORDER IN ANIMALSIN ANIMALS Naveen Kumar PhD Scholar Department of Veterinary Pharmacology and Toxicology CVSc, GBPUAT, Pantnagar, Uttarakhand E_mail: knaveen7v@gmail.com 1
2
Most commonly encounter diseases in veterinary clinical practices Diseases affecting the peripheral nerves: hypothyroid neuropathy, diabetic neuropathy, and immune mediated neuropathy Diseases affecting the neuromuscular junction: botulism, tick paralysis, and myasthenia gravis Diseases affecting the muscles: myositis, myotonia, muscular dystrophy, and metabolic myopathies 3
Out of these the most commonly reported diseases in our clinic are: MYASTHENIA GRAVIS (MG) Disease of the neuromuscular junction characterized by fluctuating weakness of certain skeletal muscle groups. 4
MG is an autoimmune disease in which antibodies are formed against ACh and a reduction in ACh receptor sites at the neuromuscular junction Acetycholine (ACh) is an important neurotransmitter that stimulates muscle tissue to contract 5
Fig. 2 6
Clinical manifestations Easy fatigability of skeletal muscle during activity Muscles involved: eyes and eyelids, chewing, swallowing, speaking, and breathing Fluctuating weakness: usually strong in the morning and progressively weaker with activity 7
Clinical manife ~ 90% of patients have eye involvement Facial mobility may be impaired Muscles of limb and trunk are less often affected No sensory or reflex loss Muscle atrophy is rare 8
Therapeutic management Anticholinesterase- prevents anticholinestersase from breaking down ACh; helps neurotransmission i.e., Prostigmine, Mestinon Corticosteroids- decrease immune response i.e., Prednisone Plasmapheresis- removes ACh antibodies; for short-term improvement 9
LARYNGEAL PARALYSIS (LP) Fig. 3 10
LP also known as Laryngeal Hemiplegia, Recurrent Laryngeal Neuropathy and in horses may be called Roaring or Roarers Syndrome Generally, large or giant breeds are most affected, especially as they get to middle age or older 11
In this condition the nerves and muscles supplying the larynx, cease to function properly, causing the cartilages at the front of the larynx to remain stationary during breathing and swallowing In a normally functioning larynx these cartilages i.e., arytenoid cartilages, open wide during inspiration, and close during swallowing, thus preventing food or water from entering the wind pipe 12
Causes of LP are mostly idiopathic and Congenital Commonly affected breeds for idiopathic LP are Irish setters and Labrador retrievers Congenital form is seen in Bouvier de Flandres, Siberian huskies, Bull terriers and Dalmatians 13
Clinical signs The signs of LP typically develop gradually and can often be misinterpreted as ageing Coughing (especially after exercise or exertion is probably the most frequently reported symptom), noisy breathing, exercise intolerance and a change in the sound of the bark (dysphonia) 14
Clinical signs In sudden severe cases the dog may develop respiratory distress with bluish mucous membranes (cyanosis) in the mouth and dog may collapse 15
Diagnosis Diagnosis is based mostly on symptoms but can only be confirmed by examining the larynx under sedation or light general anaesthesia and watching for normal movement of the arytenoids 16
Treatment Mild cases can usually be managed medically, using mild sedatives and anti-inflammatory drugs to limit the swelling around the larynx that often accompanies this condition In more severe cases may require surgery Surgery alleviates the respiratory symptoms but may increase the risk of aspiration pneumonia 17
INFLAMMATORY MYOPATHIES (IM) A heterogeneous group of disorder characterized by nonsuppurative cellular infiltration of skeletal muscle It is primarily an immune mediated polymyositis, not associated with any other systemic or infectious causes 18
Commonly observed clinical signs include weakness, exercise intolerance and a stiff gait Two forms of IM have been reported in dog- i. Generalized inflammatory myopathy (gIM) & ii. Focal inflammatory myopathy (fIM) 19
gIM used for diffuse inflammatory myopathies, including infectious and preneoplastic syndromes gIM include polymyositis (PM), an immune- mediated disorder fIM is used for the localized syndromes Both forms (gIM & fIM) of inflammatory myopathies have been reported in the dog 20
Clinical signs Clinical signs include muscle weakness, stiffed gait, and muscle atrophy Abnormally high serum creatine kinase (CK) concentrations, abnormal electromyography (EMG), histologic confirmation of lymphocytic infiltrates in skeletal muscle 21
Clinical signs .. fIM include masticatory muscle myositis (MMM) and extraocular myositis (EOM), with cellular infiltrates restricted to these particular muscle groups The most common clinical signs of fIM associated with MMM are inability to open the jaw, jaw pain, and masticatory muscle atrophy Cellular infiltrates in MMM selectively affect the muscles innervated by the mandibular branch of the trigeminal nerve, including masseter, temporalis, pterygoids, tensor tympani, and tensor veli palatini muscles 22
Diagnosis A definitive diagnosis of immune mediated polymyositis is poorly defined in veterinary medicine Although most authors agree that the disease can be diagnosed if the following features are present Clinical signs of muscle weakness Elevated serum creatinine kinase concentrations Abnormal electromyography examination with normal motor nerve conduction velocities and Muscle biopsy shows an inflammatory infiltrate 23
Treatment Treatment of immune mediated polymyositis is based on immunosuppression, initial pain relief and supportive care Prednisolone is the most commonly used immunosuppressive drug although other drugs such as aziathioprine may also be helpful, particularly if long term therapy is required to control the clinical signs 24
CANINE NEOSPOROSIS Causative organism Neospora caninum Protozoal parasite, closely related to Toxoplasma gondii Most commonly reported in puppies but may present in dogs of all ages 25
In addition to canine infections, N. caninum occurs naturally in cattle, sheep, goats, deer, and horses Neosporosis occurs worldwide, and there are no breed or sex predilections 26
Although breeds like Yorkshire terrier, Cavalier King Charles spaniel, West Highland White terrier, Border collie, Springer spaniel, Husky, Great Dane, Bernese mountain dog, Irish wolfhound, Labrador retrievers and Boxers have been well represented 27
Clinical signs The course of the disease is variable Neosporosis is a neuromuscular disease usually characterized by ascending paralysis The most commonly syndrome involves- hindlimb paresis (which progresses to paralysis), forelimb weakness and difficulty in swallowing and breathing resulting in death of animal 28
Clinical signs.... Death results from the progressive paralysis and meningoencephalomyelitis, heart failure, pneumonia In peracute cases, animals dying within 1 week of the first signs being noticed It is an important cause of stillbirth and abortion in cattle but no natural cases have yet been reported in cats or humans 29
Clinical signs.... In chronic cases (in which signs gradually progress over several weeks). Initially owners often notice a bunny-hopping type of gait, a reluctance to jump up or a splaying out of legs when squatting Other signs: Paresis/Paralysis of forelimb(s) only, ataxia, gait abnormalities, altered behaviour, blindness, head tilt, tremors, seizures, pneumonia, myocarditis (may cause sudden death) and/or nodular/ulcerative dermatitis may present in dog 30
Thanks For your kind attention 31

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Neuromuscular diseases in animals

  • 1. NEUROMUSCULAR DISORDERNEUROMUSCULAR DISORDER IN ANIMALSIN ANIMALS Naveen Kumar PhD Scholar Department of Veterinary Pharmacology and Toxicology CVSc, GBPUAT, Pantnagar, Uttarakhand E_mail: knaveen7v@gmail.com 1
  • 2. 2
  • 3. Most commonly encounter diseases in veterinary clinical practices Diseases affecting the peripheral nerves: hypothyroid neuropathy, diabetic neuropathy, and immune mediated neuropathy Diseases affecting the neuromuscular junction: botulism, tick paralysis, and myasthenia gravis Diseases affecting the muscles: myositis, myotonia, muscular dystrophy, and metabolic myopathies 3
  • 4. Out of these the most commonly reported diseases in our clinic are: MYASTHENIA GRAVIS (MG) Disease of the neuromuscular junction characterized by fluctuating weakness of certain skeletal muscle groups. 4
  • 5. MG is an autoimmune disease in which antibodies are formed against ACh and a reduction in ACh receptor sites at the neuromuscular junction Acetycholine (ACh) is an important neurotransmitter that stimulates muscle tissue to contract 5
  • 7. Clinical manifestations Easy fatigability of skeletal muscle during activity Muscles involved: eyes and eyelids, chewing, swallowing, speaking, and breathing Fluctuating weakness: usually strong in the morning and progressively weaker with activity 7
  • 8. Clinical manife ~ 90% of patients have eye involvement Facial mobility may be impaired Muscles of limb and trunk are less often affected No sensory or reflex loss Muscle atrophy is rare 8
  • 9. Therapeutic management Anticholinesterase- prevents anticholinestersase from breaking down ACh; helps neurotransmission i.e., Prostigmine, Mestinon Corticosteroids- decrease immune response i.e., Prednisone Plasmapheresis- removes ACh antibodies; for short-term improvement 9
  • 11. LP also known as Laryngeal Hemiplegia, Recurrent Laryngeal Neuropathy and in horses may be called Roaring or Roarers Syndrome Generally, large or giant breeds are most affected, especially as they get to middle age or older 11
  • 12. In this condition the nerves and muscles supplying the larynx, cease to function properly, causing the cartilages at the front of the larynx to remain stationary during breathing and swallowing In a normally functioning larynx these cartilages i.e., arytenoid cartilages, open wide during inspiration, and close during swallowing, thus preventing food or water from entering the wind pipe 12
  • 13. Causes of LP are mostly idiopathic and Congenital Commonly affected breeds for idiopathic LP are Irish setters and Labrador retrievers Congenital form is seen in Bouvier de Flandres, Siberian huskies, Bull terriers and Dalmatians 13
  • 14. Clinical signs The signs of LP typically develop gradually and can often be misinterpreted as ageing Coughing (especially after exercise or exertion is probably the most frequently reported symptom), noisy breathing, exercise intolerance and a change in the sound of the bark (dysphonia) 14
  • 15. Clinical signs In sudden severe cases the dog may develop respiratory distress with bluish mucous membranes (cyanosis) in the mouth and dog may collapse 15
  • 16. Diagnosis Diagnosis is based mostly on symptoms but can only be confirmed by examining the larynx under sedation or light general anaesthesia and watching for normal movement of the arytenoids 16
  • 17. Treatment Mild cases can usually be managed medically, using mild sedatives and anti-inflammatory drugs to limit the swelling around the larynx that often accompanies this condition In more severe cases may require surgery Surgery alleviates the respiratory symptoms but may increase the risk of aspiration pneumonia 17
  • 18. INFLAMMATORY MYOPATHIES (IM) A heterogeneous group of disorder characterized by nonsuppurative cellular infiltration of skeletal muscle It is primarily an immune mediated polymyositis, not associated with any other systemic or infectious causes 18
  • 19. Commonly observed clinical signs include weakness, exercise intolerance and a stiff gait Two forms of IM have been reported in dog- i. Generalized inflammatory myopathy (gIM) & ii. Focal inflammatory myopathy (fIM) 19
  • 20. gIM used for diffuse inflammatory myopathies, including infectious and preneoplastic syndromes gIM include polymyositis (PM), an immune- mediated disorder fIM is used for the localized syndromes Both forms (gIM & fIM) of inflammatory myopathies have been reported in the dog 20
  • 21. Clinical signs Clinical signs include muscle weakness, stiffed gait, and muscle atrophy Abnormally high serum creatine kinase (CK) concentrations, abnormal electromyography (EMG), histologic confirmation of lymphocytic infiltrates in skeletal muscle 21
  • 22. Clinical signs .. fIM include masticatory muscle myositis (MMM) and extraocular myositis (EOM), with cellular infiltrates restricted to these particular muscle groups The most common clinical signs of fIM associated with MMM are inability to open the jaw, jaw pain, and masticatory muscle atrophy Cellular infiltrates in MMM selectively affect the muscles innervated by the mandibular branch of the trigeminal nerve, including masseter, temporalis, pterygoids, tensor tympani, and tensor veli palatini muscles 22
  • 23. Diagnosis A definitive diagnosis of immune mediated polymyositis is poorly defined in veterinary medicine Although most authors agree that the disease can be diagnosed if the following features are present Clinical signs of muscle weakness Elevated serum creatinine kinase concentrations Abnormal electromyography examination with normal motor nerve conduction velocities and Muscle biopsy shows an inflammatory infiltrate 23
  • 24. Treatment Treatment of immune mediated polymyositis is based on immunosuppression, initial pain relief and supportive care Prednisolone is the most commonly used immunosuppressive drug although other drugs such as aziathioprine may also be helpful, particularly if long term therapy is required to control the clinical signs 24
  • 25. CANINE NEOSPOROSIS Causative organism Neospora caninum Protozoal parasite, closely related to Toxoplasma gondii Most commonly reported in puppies but may present in dogs of all ages 25
  • 26. In addition to canine infections, N. caninum occurs naturally in cattle, sheep, goats, deer, and horses Neosporosis occurs worldwide, and there are no breed or sex predilections 26
  • 27. Although breeds like Yorkshire terrier, Cavalier King Charles spaniel, West Highland White terrier, Border collie, Springer spaniel, Husky, Great Dane, Bernese mountain dog, Irish wolfhound, Labrador retrievers and Boxers have been well represented 27
  • 28. Clinical signs The course of the disease is variable Neosporosis is a neuromuscular disease usually characterized by ascending paralysis The most commonly syndrome involves- hindlimb paresis (which progresses to paralysis), forelimb weakness and difficulty in swallowing and breathing resulting in death of animal 28
  • 29. Clinical signs.... Death results from the progressive paralysis and meningoencephalomyelitis, heart failure, pneumonia In peracute cases, animals dying within 1 week of the first signs being noticed It is an important cause of stillbirth and abortion in cattle but no natural cases have yet been reported in cats or humans 29
  • 30. Clinical signs.... In chronic cases (in which signs gradually progress over several weeks). Initially owners often notice a bunny-hopping type of gait, a reluctance to jump up or a splaying out of legs when squatting Other signs: Paresis/Paralysis of forelimb(s) only, ataxia, gait abnormalities, altered behaviour, blindness, head tilt, tremors, seizures, pneumonia, myocarditis (may cause sudden death) and/or nodular/ulcerative dermatitis may present in dog 30
  • 31. Thanks For your kind attention 31