Equine Med- Skele MM disorders 1

wilsbach's version from 2016-04-30 17:42

intro + exertional

Question Answer
mm can respond to injury in what 3 possible ways?(1) necrosis (2) atropy (3) hypertrophy
some reasons mm would necrose in response to injury?Calcium metabolism, Free radical damage, Release of enzymes
reasons mm might atrophy in response to injury?disuse, neurogenic, Cachexia, myositis
whats sweeny?damage to suprascapular nerve-- leads to atrophy of the supraspinatus and infraspinatus muscles
hypertrophy is usually due to...conditioning/compensatory
2 major categories of myopathies in horses? how do you differentiate them?exertional or nonexertional-- how to tell is WAS THERE RECENT EXERCISE?
skeletal mm specific enzyme?CK (creatinine kinase)
what is normal CK levels? what would make you concerned about severe mm damage? What if its mildly elevated?<300 IU/L is a NORMAL amount...if it's elevated a bit, say to like 1000, consider if they have been laying down a while or just took a trailer ride. SEVERE mm damage you will see >10,000
what other enzyme which is not CK can indicate mm damage? what else can it indicate?Aspartate aminotransferase (AST) released from mm AND from liver (hepatocyte damage). So have to consider this.
which has a longer half life- CK or AST? AST hangs around longer than CK... but CK is usually the first one to pop up. (ofc the non-specific one would hang around longer..) CK usually gone by 24hr but elevated AST can hang around for weeks
What might a US look like with mm damage? what should you do about it?might have BROWN PEE because of MYOGLOBINURIA. However, This pigmented substance can be harmful to the kidneys so you should provide lots of IV fluids till they pee clear.
what is myoglobinuria coming from?HIGH CK
If you need to take a mm bx, where is a good area to do it?back of the thigh under the tail, to hide the scar for owners
3 mm diagnostic tests you can perform?(1) biopsy (2) exercise test (3) Electromyography (fancy university test)
explain an exercise test- what is a positive for mm problem result?Measure CK --> exercise them --> 4 hours later measure CK again. In a normal horse, the post-exercise CK shouldn't go above like a 1000. Positive for a problem if value doubles or if CK >1000 IU/L
value of exercise test in normal horse is _________ should never go above _________CK should never go above 1000 (or double the value it was before exercise)
what is "tying up"?exertional rhabdomyolysis
2 types of exertional myopathies, explain them a bit (1) sporadic: acute onset and emergency therapy required (2) recurrent: Generally breed related, and less severe than sporadic
which exertional myopathy is the emergency?sporadic
What are some triggers for a case of sporadic exertional rhabdomyolysis? What are some things which can make it worse?Usually triggered by a sudden change in exercise pattern, or performing beyond their conditioning level. It can be exacerbated by.. electrolyte imbalances, hormone imbalances, concurrent illness
should you bx a sporadic exertional ER?no- prolly wont see anything. not to mention its mean that theyre all painful and then you're gonna poke a hole in it- ow.
what are the staples of tx for treating a sporadic exertional rhabdomyolysis?(1) Decrease muscle damage with REST REST REST!! as well as NSAIDs. (2) FLUIDS FLUIDS FLUIDS. This helps regulate electrolytes and acid-base (muscle probs can def mess with electrolytes, or the electrolyte prob could have helped trigger the prob in the first place) If cant' afford IV can do NG, but make sure it is isotonic (elyte balance). Fluids will also support kidney function and help flush out possible myoglobin. (3) pain management (4)
What are Dantrolene sodium & Methocarbamol for?Dantrolene: dec Ca release at sarcoplasmic reticulum-- mm relaxant. Methocarbamol reduces mm spasm (MOA not understood)
RECURRENT rhabdomyolysis is a genetic problem-- what are the three conditions?(1) Polysaccharide storage myopathy (2) recurrent exertional rhabdomyolysis (3) mitochondrial myopathy (she had this under the non-exertional section)
WHO genetically gets polysaccharide storage myopathy?Quarter Horses, appaloosas, paints. Also warmbloods and draft breeds (That giant butt is so sweet and warm and speckly)
WHO gets recurrent exertional rhabdomyolysis?thoroughbreds (thoRERbreds)
WHO gets mitochondrial myopathy?arabians (ornately decorated arabic mitochondria)
most of the time you can dx recurrent ER based on...history and signalment. Is it tying up every time you ride it? Is it a quarter horse? Prolly PSSM
which do you mm bx- sporadic or recurrent ER?recurrent- to dx it you will see what the prob is (will not see anything with the sporadic)
can recurrent ER present acute?yes- can be acute or just be a little off.
***WHEN do you perform mm bx for recurrent ER?*NOT DURING AN ACUTE EPISODE.
Explain cause and pathogenesis of Polysaccharide storage myopathyDue to a genetic mutation in an enzyme!! The prob is mm cannot generate enough energy bc of two reasons: (1) Enhanced insulin sensitivity: All of the glucose is gobbled up really fast. (2) Increased synthesis of less branched glycogen (aka shitty, inappropriate glycogen) --> RESULT: inappropriate polysaccharide storage
what are the two types of PSSM? explain them a bit(1) TYPE 1: Genetic mutation identified as the GSY1 Gene. (5-7% of all QG/Paints/Appaloosas) It is an AUTOSOMAL DOMINANT trait so there is a 50% chance foal will be affected (prolly shouldn't breed). (2) TYPE 2: gene not identified yet. heritability unknown, but has same pathophys as type 1
how does PSSM usually present?there is variable presentation but usually dec performance. You will see generally MILD typing up after exercise. RARELY there will be severe mm wasting.
How can you dx PSSM-- definitively? For Type 1? Type 2?(1) there is a genetic test but this only is available for type 1 (only know gene for type one). Can use hair or whole blood. (2) MM Bx will diagnose both types. Bx semimembranosus. Stain for ABNORMAL GLYCOGEN (PAS stain- periodic acid shift). 100% sensitive test
which dx test can dx both type 1 and type 2 PSSM?BX and staining- genetic test can only detect type 1
how to tx/manage PSSM?There is NO CURE but you can manage this. You must provide CONSISTENT exercise and you want to change the diet to be low in soluble carbs (cant gobble up the glucose as fast due to the inc insulin sensitivity) so want lots of grass hay. If they need more calories-- add fat only!!
So RER is in TBs.... but who is most likely to have it out of that group?YOUNG OR FEMALES
how do _________(who) get RER (recurrent exertional rhabdomyolysis)? What is the signs/pathogenesis of it? TH'RER'BREDS get it- genetic, possibly autosomal dominant. (about 5% of TBs affected). sign of intracellular calcium dysregulation.
how do you dx recurrent exertional rhabdomyolysis? (RER)dx often presumptive, but you can do a mm bx to see inc # of central nuclei and no PAS(periodic acid schiff- the polysaccharide stain) positive mm
how do you manage RER?same as PSSM- CONSISTENT exercise, LOW soluble carbs (lots of grass hay) and make sure the electrolytes are balanced!