L16: Muscle Diseases Of Ruminants (Mallicote) Flashcards
Inflammatory muscular diseases
Clostridial myositis Protozoal infection (Sarcocystis)
Etiology of clostridial myositis
- anaerobic, spore-forming bacteria
- requires CREATION OF anaerobic conditions**
- initial entry routes: inoculation or ingestion of spores
Organism that causes blackleg
Clostridium chauvoei
Organism that causes gas gangrene
C. Perfringens
Risk factors for clostridial myositis
- may occur repeatedly at same locale
- C. Chauvoei assoc. with warmer months
- C. Sordelli assoc. with older feedlot cattle
- wound infections: C. Perfringens, C. Septicum, C. Novyi
- sheep/goats: shearing, tail docking, dehorning
- IM injections
- parturition
- fighting rams
- shearing, docking, castration
- rapidly growing animals on high nutrition plane
Pathogenesis of Clostridium
After ingestion/inhalation, spores disseminate to muscle. They can be vegetative until anaerobic conditions created (ie. Via trauma) –> proliferation of bacteria –> exotoxins released –> muscle damage, systemic effects
CS of clostridial myositis (peracute)
- sudden death may be only finding
- peracute bacterial proliferation
CS of longer (protracted) course of clostridial myositis
- fever
- tachypnea
- tachycardia
- lameness +/- swelling at site of infection
- swelling is hot, painful, fluctuant, malodorous sanguinous fluid, +/- draining, areas can be cold to touch
- very high rate of mortality
- cattle down, sheep reluctant to move
Clin path of clostridial myositis
- severe hemoconcentration and dehydration
- normal to increased WBC with L shift
- muscle enzymes inconsistent
Dx of clostridial myositis**
1) Hx, CS
2) Isolation of organism from live animal:
- smear: large G+ rods
- FA
- culture of fluid/muscle (won’t help patient directly)
3) Post-mortem:
- gross pathology: crepitus, bloody fluid, rancid butter odor
- IFA or direct smear
Tx of clostridial myositis
-prognosis extremely poor
-penicillins** prevent further proliferation
anti-inflammatories
incision/drainage, flush w/ H2O2
-supportive care
-must convert anaerobic env. To aerobic env.!
Prevention of clostridial myositis
- investigate potential sources of injury
- minimize chute trauma
- counsel clients
- passive Ab in calves is protective
- multivalent vaccines starting at 4 mo.: 7 or 8-way for cattle
- small ruminant vaccine
Sarcocystis cruzi
-protozoa that encysts in muscle and can cause neuro dz
White Muscle Disease etiology
- affects most rapidly growing calves, lambs, kids
- more common in areas with selenium deficient soil, poor quality forage
Role of selenium
- protection from oxidation injury
- important for muscle cell membrane integrity
Vitamin E role
Protects from superoxide damage
Pathophys. Of white muscle dz
-lipid peroxidation of muscle membrane –> diffuse muscle degeneration
2 forms of white muscle disease
Skeletal
Cardiac
CS of skeletal form of white muscle dz
-stiffness, weakness, recumbency
-pain, m. Tremors
+/- resp. Signs (fx of muscles required for respiration affected)
CS of cardiac form of white muscle dz
- heart murmurs
- pulm. Edema
- sudden depression, death
Clin path of White Muscle Disease
Myoglobinuria
Increased CK, AST, LDH
Plasma Vitamin E
White Muscle Disease on histology
-necrotic muscle fibers surrounded by macs
Tx of White Muscle Disease
- Selenium preparations
- Vitamin E
- Antioxidants (ie. Vit. C, N-acetyl cystein)
- supportive care (ie. Abx if risk of pneumonia)
- find root of the problem
Toxic myopathies
Gossypol (feed additive)
Senna (Cassia)
Tremetol-containing plants (rayless goldenrod, white snakeroot)
Ionophores (monensin, lasalocid)
Etiology of gossypol
- comes from cottonseed meal
- toxic to monogastrics and pre-ruminants
- causes peritoneal, pericardial, and pleural fluid accumulation; myocardial necrosis, liver damage
ionophores
Anti-coccidial and growth-promoting feed additives
- causes cardiac and skeletal m. Necrosis
- CS relate to cardiac dysfx
Predisposing conditions to traumatic myopathy
- metabolic dz
- neuro dz
- recumbency
Dx of traumatic myopathy (rhabdomyolysis)
- firm musculature in acute period
- myoglobinuria
- CK values >5000
- elevated AST (more useful with chronic recumbency and previous m. Trauma; longer half-life than CK)
Tx of traumatic myopathy
- resolve underlying cause**
- fluids
- NSAIDs
- vit. E/Sel (anti-oxidants)
- nursing care
Inherited myopathies
Phosphorylase deficiency: Charolais cattle
Myofiber hyperplasia: Belgian blues
Myotonia congenita: fainting goats
Etiology of phosphorylase deficiency
- mutation in charolais
- exercise intolerance/collapse
- serum CK elevated
- genetic screening
Etiology of myofiber hyperplasia
- inherited mutation of type 2B muscle fibers
- more likely to have elso heel, dystocia, jaw deformities
- belgian blues
Etiology of myotonia congenita
- tetanic m. Contractions when startled
- delay in m. Cell relaxation (interruption of Cl channels in muscle cells)
- autosomal dominant w/ incomplete penetrance
Types of muscular diseases
Inflammatory Nutritional Toxic Traumatic Inherited
