Lecture 16 Muscle Pathology Flashcards
What (4) types of neoplasms are derived from skeletal muscle?
- Rhabomyoma
- Rhabdomyosarcoma
- Fibrosarcoma
- Lipoma
Which is more common, rhabdomyoma OR rhabdomyosarcoma?
Rhabdomyosarcoma
True or Flase:
- Infiltrating lipomas are harder to totally remove becuase of their quick growth rate.
- Infiltrating lipomas do NOT metastasize.
- FALSE: infiltrating lipomas are harder to totally remove, so they do tend to recur after surfical removal, but their growth is SLOW
- TRUE: lipomas do NOT metastasize
Which type of collagen are tendons primarily composed of?
Type I
True or False:
Tendons have an impaired ability to heal when injured, dispite a heafty blood supply.
FALSE
Tendons have an impaired ability to heal becuase of a MEAGER BLOOD SUPPLY
How are tendon sheaths similar to a joint?
Both are lined by synovium, which allows for the same lubricating effect
What is the condition called when tendons are shorter than normal?
Contracted tendons
Are contracted tendons a congential defect OR genetic defect?
Congenital
When contracted tendons are severe, what other developmental abnormality might you find grossly?
Hypoplastic muscle development
What is the lesion most commonly found in tendons?
Tears or ruptures due to traumatic injury
An animal is presented to you with a ruptured tendon. What might you inform the owner of regarding this animal’s healing process?
When a tendon ruptures, the healing that occurs is usually via fibrosis, producing a TYPE III COLLAGEN, which does not have the same tensile strength as tpye I. The healed tendon will be more prone to break down again!!!
What is a term used for the inflammation of a tendon and the sheath around it?
Tenosynovitis
What is your diagnosis?
Ruptured tendon
Which muscles are involved in EOSINOPHILIC MYOSITIS in dogs?
Muscles of mastication: masseter, temporalis, and pterygoid muscles
What is believed to be the cause of eosinophilic myositis in dogs?
The muscles it affects (muscles of mastication) are composed of a unique type 2M muscle fiber. It is believed that this is an immune-mediated myositis in which autoantibodies are produced against a protein specific to the type 2M fibers.
You are presented with a dog that has intermittent episodes where he does not want to eat. What muscle condition might you want to heavily consider?
Eosinophilic myositis
(This condition causes inflammation in the muscles of mastication during actue, intermittent episodes)
What might eosinophilic myosiitis of a dog progress to?
The inflammation can result in fibrosis and atrophy of the muscles of mastication
What is the term for end stage myositis?
Atrophic myositis
Neosporosis, due to infection with Neospora caninum, will cause ____ ____ in dogs.
Neosporosis, due to infection with Neospora caninum, will cause NECROTIZING MYOSITIS in dogs.
How might a dog become infected with NEOSPOROSIS?
By eating bovine fetuses aborted due to neosporosis
What is myasthenia gravis?
Myasthenia gravis is general muscle weakness due to a decrease in acetylcholine (ACH) receptors at myoneural junctions
How might an animal get myasthenia gravis?
- Congenital
- Overall low number of ACH receptors at the myoneural junction
- Acquired
- Autoimmune disease - antibodies attack the ACH receptors
A dog presents to you for resent episodes of regurgitation. After running radiographs, you diagnose megaesophagus.
What other condition might you want to check for now?
Myasthenia gravis
- What is the common name of Equine Rhabdomyolysis?
- What type of change in the muscle is this condition associated with?
- Is this monophasic OR polyphasic?
- “Monday morning disease”
- Acute myodegeneration
- Monophasic
What might the recent history of a horse that presents with Equine Rhabdomyolysis?
AKA : exertional myopathy
A working horse on a high grain diet, housed on over the weekend (not worked), and put back to heavy work on Monday.
- Acute myodegeneration associated with Equine Rhabdomyolysis causes the liberation of what substance?
- How can this be tested clinically?
- Myoglobin is liberated from damaged muscle
- Causes myoglobinuria - test the urine, will be darkened in color
Horses who come down with Equine Rhabdomyolysis may likely have what other condition?
Equine polysaccharide storage myopathy
Equine polysaccharide storage myopathy is the accumulation of _____ aggregates in ____ ___ ____.
Equine polysaccharide storage myopathy if the accumulation of polysaccharide aggregates in type 2 myocytes.
True or False:
Equine polysaccharide storage myopathy (EPSM) is a congenital defect.
FALSE
EPSM is a GENETIC defect
Equine polysaccharide storage myopathy can result in muscle atrophy; why?
Due to repeated bouts of myodegeneration
Hyperkalemic periodic paralysis is a defect in what?
Explain how this defect causes hyperkalemia.
Defect in sodium channels –> causes sodium channels to be more permeable than normal –> this causes polarization abnormalities –> myotonia –> hyperkalemia
Which of the following diseases is caused by an autosomal dominant trait? :
- Exertional myopathy
- Equine polysaccharide storage myopathy
- Hyperkalemic periodic paralysis
Hyperkalemic periodic paralysis
These samples are from a horse.
- Based on the color change in the urine and the kidney, what is your most likely diagnosis?
- What causes this color change?
- Equine rhabdomyolysis ( with myoglobinuria and myoglobin nephropathy)
- Myoglobin