Muscle Pathology II

What is the most common cause of clostridial myositis in equines?

C. Septicum

What is the pathogenesis of Clostridal myositis in horses?

Clostridium gets into muscles via penetrated wounds and proliferates in anaerobic conditions

What are signs of all clostridial myositis?

Hemorrhagic mucles

Necrosis

Gas bubbles

Identify the pathology?

Clostridial myostits - muscle necrosis

What will clostridium botulinum do?

Prevents release of ACh leading to a flaccid paralysis

What is used to dx Botulism?

Exclusion - toxin found in stomach contents/ food

-NO Findings on necropsy

What will cause pigeon fever?

Corynebacterium pseudotuberculosis - gram + anaerobic bacteria

How does Corynebacterium pseudotuberculosis cause dz?

Phospholipid D causes vascular damage - inhibits neutrophils

What are clinical signs of Corynebacterium pseudotuberculosis?

Intramuscular abscesses mostly in pectoral musculature

What is purpura hemorrhagica?

Type 3 hypersensitivity attacking vasculature

-IgA and strep M antigen cause infarction

What are clinical signs of purpura hemorrhagica?

Myoglobinuria

Elevated CK and AST

Cutaneous hemorrhage

How is purpura hemorrhagica different from clostridial myositis?

No gas bubbles

What is streptococcal associated rhabdomyolysis and muscle atrophy?

An immune mediated damage due to cross reaction of muscle proteins and strep antigen - MHC will be increased on muscle membranes

What are classical signs of streptococcal associated rhabdomyolysis and muscle atrophy?

Muscle atrophy over the paraspinal and gluteal muscles

-high elevation of CK and AST (no purpura hemorrhagica signs)

What animals are most commonly affected by streptococcal associated rhabdomyolysis and muscle atrophy?

Young Quarter horses

What stain is used to see streptococcal associated rhabdomyolysis and muscle atrophy

IHC -Lymphocytes between muscles and perivascular lymphocytic cuffing

In most species Sarcocystis will be an ___ finding?

Insidental - protozoal

What does a lack of vitamin E and selenium do to the muscle?

Ehnance oxidative inj

What horses are most susceptible to nutritional myopathy?

Foals to young adults problems swallowing/ atrophy of masticatory muscles

What animas are most susceptible to iodophore tox?

Horses - Ca2+ over load leading to sk and cardiac muscle necrosis

-replaced by fibrosis

What is going to cause equine polysaccharide storage myopathy (EPSSM)?

Autosomal dominant trait due to a mutation of Glycogen synthase 1 gene - Glycogen storage dz

What is the dx for EPSSM?

PAS - histology preferred

Identify the pathology?

EPSSM - Glycogen granules in muscle

What is going to cause Glycogen branching enzyme deficiency?

Autosomal recessive trait - deficiency of GBE type 4- no glycogen branching

What stain is used to dx GBE deficiency?

PAS - Globs of glycogen

Most animals w/ GBE deficiency will be ___?

Still born/ aborted - not tx

What is equine exertion rhabdomyolysis?

Tying up - Stiff gait/ reluctancy to move w/ swelling and necrosis of muscles - during or after exercise

What will cells will equine exertion rhabdomyolysis target?

Type 2 myofibrils

What is ischemic myopathy?

Pressure vasculature due to recumbency causing infarct and necrosis of pectoral, abdominal and limb muscles

What endocrine disorder in horses can lead to muscle atrophy and type 2 atrophy with weakness?

PPID

What is Sweeney?

Unilateral scapular muscle atrophy - trauma to the supra scapular nerve -poorly fit harness

What is stringhalt in horses?

Exaggerated flexion of one or both hindlimb

What plant in Australia can cause stringhalt?

Hypochoeris radicatus

What will cause equine protozoal myeloencephalitis?

Sarcocystis neurona (rarely Neospora)

-denervation atrophy of facial and gluteal muscles

What causes Equine motor neuron dz?

Vit E deficiency - rapid muscle wasting -yellow to tan gelatinous texture of muscle

What is going to cause clostridial myositis black leg in cattle?

Clostridium chauvoei

What is the pathogenesis of clostridial myositis in cattle?

Ingestion of organism to the muscle then trauma all lead to anaerobic environment and toxin production - hemorrhage, edema, necrosis

What botulism toxins are Cattle most susceptible to?

C and D

how will a muscles be infected w/ Trueperella pyogenes and what will they look like?

Via contamination of wounds -> Yellow-green w/ foul-smelling

What causes wooden tongue?

Actinobacillus lignieresii - granulomatous/ fibrosing glossitis

What is going to cause Lumpy jaw?

Actinomyces bovis - osteomylitis - boney proliferation = lumpy

What is eosinophilic myositis?

A sarcocystis infection of cattle that leads to a hypersensitivity - green coloration of muscle

What will Neospora caninum do to cattle?

No clinical dz in adults

Abortion

What is the most common plant toxicity that causes degenerative myopathy in cattle?

Senna occidentalis

What is steatosis?

Muscle replacement w/ adipocytes

What stains can be used to see steatosis?

Oil-redO stain or Sudan black stain

What is the most common inherited myopathy of cattle?

Defect of myostatin gene - congenital muscular hyperplasia - double muscling

What does prosopis glandulosa cause in goats?

Degenerations of motor nucleus of trigeminal nerve -> masticatory muscles - emaciation from lack of eating

What is myotonia in goats?

Inherited autosomal dominant defect in skeletal muscle Cl channels

What are clinical signs of myotonia in goats?

Fainting goats - stiffness for 5-20s

What is going to cause clostridial myositis (Malignant edema) in pigs?

C. septicum

What are signs of clostridial myositis in pigs?

Swelling of neck and blue color

Gangrene

What is a parasitic myopathy that is in pigs?

Trichinella spiralis

What is the pathology of parasitic myopathy in pigs?

Lives in SI moves to blood stream and encysts on myofibers in the diaphragm masticory and intercostal muscles

Cassia occidentali will affect the ___ and gossypol will affect the ___?

Diaphragm

Sk muscle/ cardia muscle

What is Myofibrillar hypoplasia/ splay leg?

Young piglets will abduct limbs progressively flattening the sternum

What is malignant hyperthermia?

Defect in ryanodine receptors - excessive contrations leads to increased heat production

- halothane anesthesia/ stress causes

What is going to cause protozoal myopathy in dogs?

Neospora caninum- affect ventral spinal roots causing denervation atrophy of muscles

What is going to cause X-linked muscular dystrophy in dogs?

Dystrophin gene defect

- leads to progressive weakness

- Resp failure related to sever diaphragmatic necrosis

-death

How is X-linked muscular dystrophy in dogs DX?

Muscle biopsy IHC - lack of brown means dystrophin is missing

What are clinical signs of Labrador retriever Centronuclear myopathy?

Neuromuscular weakness due to recessive trait

What is Polymyositis?

Antibodies against sk muscle - lymphocytic t-cell rich necrosis

-chronic can see Fibrosis

What is masticatory myositis?

Antibodies agains type 2M myosin - B-lymphocytes and eosinophils

What are clinical signs of masticatory myositis?

Bilateral symmetric swelling of temporals and master muscle - can't open mouth

How is masticatory myositis and polymyositis differentiated?

Serology testing for anti type 2M myosin antibodies

How is X-linked muscular dystrophy different in cats?

Hypertrophy of muscles

How does FIV cause myositiosi?

Lymphocytic inflammation w/ T cells

What metabolic condition will cause peripheral neuropathy/ denervation of atrophy?

Diabetes mellitus