Equine Muscle Disease I

what is myotonia

delayed relaxation or prolonged contraction of skeletal muscles

muscle fasciculations and weakness

what does mean HYPP

hyperkalemic periodic paralysis

what is HYPP

autosomal dominant trait, mutation in SCN4A

abnormal voltage Na channel

increased muscle excitability

horse homozygous for HYPP

more severe

what can trigger HYPP

sudden diet change, high K food

stress

UNPREDICTABLE!

what happens initially in HYPP

brief episode of myotonia (prolapse of 3rd eyelid)

sweating

muscle fasciculations

what happens as HYPP episode progresses

more generalized, additional muscle groups

swaying, staggering

tachycardia, tachypnea

normal

how to diagnose HYPP

genetic testing!!

hyperkalemia not always present, transitory

hemoconcentration

how to prevent HYPP

decrease potassium intake, let graze and use later cutting hay

• feed small rain meals frequently, used formulated diet

increase potassium loss with diuretics (acetazolamide)

avoid triggers

how to treat HYPP

mild: grain and Karo syrup, walk

dextrose to get K back into cell

calcium gluconate to raise membrane threshold potential

acetazolamide, diuretic

does HYPP result in rhabdomyolysis

NO!!!

what does GBED mean

glycogen branching enzyme deficiency

what is GBED

autosomal recessive mutation, GBE1

accumulation of unbranched glycogen

inability to store glucose, lack of fuel

only homozygous get sick= death

what are the clinical signs of GBED

abortion, still birth

intermittent seizures

muscle weakness

increased CK, AST, and GGT

leukopenia

hypothermia

what is seen on histopathology in GBED

basophilic inclusions in skeletal and cardiac muscle

PAS positive= globular/ crystalline inclusions

what are muscle cramps

due to repetitive firing of nerve and its motor unit

muscle contracture occurs from shortening sarcomere with depolarization

what is lost from sweat

Na

K

CL

Mg

Ca

what are clinical signs of exhaustion

dull, depressed, dehydrated

increased TPR

muscle stiffness and spasm

what can cause exhaustion in endurance horses

prolonged exercise in hot humid weather

what are clinical signs of synchronous diaphragmatic flutter

diaphragm contracts with each heart beat

thumps audible sound

low calcium and hypochloremic metabolic alkalosis

what can cause hypocalcemia

decreased absorption, increased losses

lactating mares

CS

what are the clinical signs of hypocalcemia

increased excitability

increased muscle tone, wtiff gait

profuse sweating

tachycardia, dysrhythmias

what are clinical signs of ear tick associated muscle cramping

intermittent painful muscle cramps, not from exercise

lasts minutes-hours

tick in external ear canal

how to treat ear tick associated muscle cramping

local pyrethrin

acepromazine

when treating hypocalcemia

administer slowly and monitor cardiovascular response

what causes synchronous diaphragmatic flutter

phrenic nerve fires in synchrony with atrial depolarization

prolonged exercise, hypocalcemia, stress

What disease on the 5 panel plus test for QH is not related to musclr

hereditary equine regional dermastenia

which of the diseases on the 5 panel plus for QH has autosomal recessive inheritance pattern

glycogen branching enzyme deficiency

hereditary equine regional dermatenia

what disease is always fatal

glycogen branching enzyme deficiency

If a dam and sire that are both GBED carriers are bred, what are the chances to produce offspring that shown clinical signs of GBED

25%