who causes tetanus? what is the pathophys of the dz?
Clostridium tetani elaborates tetanospasm toxin--> Retrograde travel into the CNS--> Inhibits glycine(inhibitory) at interneurons in the spinal cord and brainstem --> Uncontrolled muscle contraction (so inhibit the inhibitor--> spasm)
Thromboembolic disease. Predisposing dz(see other card) leads to Thrombus in the distal aorta--> Ischemic injury to peripheral nerves/muscle of the pelvic limb
explain dzs which cause ischemic neuromyopathy in DOGS VS CATS
CATS: hypertrophic cardiomyopathy, thyrotoxic cardiomyopathy.... DOGS: Cushing’s syndrome, renal failure, pancreatitis, IMHA, etc...... for both, leads to: Thrombus in the distal aorta
CSs of Ischemic Neuromyopathy?
Acute onset of paraparesis/paraplegia--> Hypalgesia/analgesia of the distal limbs. Rectal hypothermia, cool paws, cyanotic nail beds, absent femoral pulses. In DOGS, also see patellar areflexia (absent reflex)
diff ways you can dx ischemic neuromyopathy?
Clinical signs/history, Abdominal and cardiac ultrasound, MRI, Creatine kinase elevation, hyperkalemia, acidosis, Paired thoracic/pelvic limb lactate and glucose
tx for ischemic neuromyopathy? prog?
Anti-thrombus medication, Surgical thrombus removal. Prog is guarded ( Depends on the underlying etiology, amount of Reperfusion injury)
**pathophys of ACQUIRED FORM of MG?
Antibodies form against the nicotinic ACh receptor (parasymp system). This happens in association with Dzs like: Hypothyroidism, thymoma (several other neoplasms as well), Methimazole therapy (used to tx hyperT).
which dog and cat breeds are prone to ACQUIRED MG?
Abyssinian, Akita, German Shepherd, golden retriever
**what is the pathophys of the CONGENITAL form of MG? which breeds of dogs are prone to this form?
Lack of or dysfunctional nicotinic ACh receptors. Jack Russell terrier, smooth-haired fox terrier, Dachshund, Samoyed are prone
**what are the GENERALIZED CSs of MG?
Exercise intolerance, Megaesophagus (regurgitation, aspiration pneumonia), Ptyalism, dysphonia, fatigable palpebral reflexes (harder and harder for them to close their eye when you continually tap on it ), Neck ventroflexion (cat), Normal myotactic reflexes
Like generalized only a peracute onset and very severe. ....Including muscles of respiration :( :( ( May require ventilatory support )
*what will thoracic radiographs (can use to dx MG) look like of MG? (3 major things to see or look for)
Megaesophagus, pneumonia (aspiration pneumonia), Thymic or other thoracic mass
**what will electromyography look like with MG?
NORMAL (Electromyography (EMG) is an electrodiagnostic medicine technique for evaluating and recording the electrical activity produced by skeletal muscles. )
**what is the electrodiagnostic you use with MG?
(electromyography will be NORMAL) Repetitive nerve stimulation will show a decremental response (can do it at first but then slowly gets worse )
*what is the GOLD STANDARD TEST for dx ACQUIRED MG?
Acetylcholine receptor antibody titers
*best way to dx CONGENITAL MG?
Muscle biopsy and immunohistochemistry
*what is a tensilon test? explain how it works
Use Edrophonium chloride, which is an ANTIcholinesterase test (so inc ACH in synapse to try to counteract the fact not all the nicotinic ACH receptors are working. should see improvement of CSs with admin). HOWEVER, Beware false positives/negatives and severe side effects (SLUDGE: salivation, lacrimation, urination, diaphoresis (sweating), Gi upset (incld diarrhea), emesis (vomiting) ) (she isnt fond of this test)
what are some anticholinesterase drugs you can use to tx MG? (2). precautions?
Pyridostigmine, neostigmine. Beware SLUD signs, so start at the low end of the dose and titrate therapy appropriately
3 drugs you can use for immunosuppressive therapy to tx MG? precautions?
Prednisone, cyclosporine, azathioprine. However this is a controversial tx bc: Some dogs undergo spontaneous remission, Many patients have concurrent aspiration pneumonia (body can't fight infection then), Steroids can contribute to weakness
what problem associated with MG will you prolly wanna address?
The megaeso and concurrent esophagitis and risk of aspiration pneumonia- give drugs to manage eso tone and esophagitis (she didn't mention what they were).....can also provide nutritional support via stomach tube, or try the bailey chair
****which drugs should you avoid in a dog with MG?
Avoid the use of NMJ-blocking drugs aka NO AMINOGLYCOSIDES
prog of MG? (consider type)
for generalized and focal the prog is guarded (Some cases undergo spontaneous remission , but megaeso might never go away--> lots of aspiration pneumonia). Acute, fulminant type: grave prognosis
what is the most common cause of death with myesthenia gravis?
Succumb to aspiration pneumonia (Or, euthanized due to constraints of dealing with repeated bouts of aspiration pneumonia )
how do you know if their MG is in remission?
Monitor serum antibody titers q6-8wk: Remission achieved when titers return to normal
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