what should you know about any drugs when it comes to txing horses with heart problems?
They are expensive, and you still can't use the horse for risk of it falling over and crushing you. But they are effective.
DIGOXIN: what is the MOA? what is it used for? what are the CIs/ SEs?
MOA: positive inotrope (inc mm contraction force) and SLOWS conduction through the AV node. USE: CHF, rate control. CI: dont use with myocardial dz. SE: depression, anorexia, colic, diarrhea.
Enalapril/quinapril: what is the MOA? what is it used for? What are the CIs/ SEs?
MOA: ACE inhibitors (vasodilation) . use: CHF. CI: dont use with hyperkalemia. SE: cough, hyperkalemia (bc inhibiting angiotensin dec aldosterone and aldosterone is Na sparing, you inhibit this an the opposite happens-- K is spared (taken back up) ) , renal dysfunction
Hydralazine: what is the MOA? what is it used for? What are the CIs/ SEs?
MOA: Arterial vasodilator (it is a sm mm relaxor) USE: LEFT sided CHF (makes sense, bc it dec afterload to L side of heart bc L side is working against the arteries). CIs: Hypotension, renal dz (need that perfusion, yo). SEs: weakness, edema
**furosemide: what is the MOA? what is it used for? What are the CIs/ SEs?
MOA: loop diuretic. USE: reduce edema, CHF. CI: not when dehydrated/ renal dz/ electrolyte imbalance
******what is the drug we specifically use to convert horses out of afib and vtach? what should we know about using it?
Quinidine!! But it is one of the most toxic drugs we give to horses-- be careful
what should you know about treating afib in horses?
the longer they are in afib the less likely they are to respond to tx (remember to tx afib you give quinidine)
**Quinidine: what is quinidine/MOA? what do we use it for? CI/SEs?
IT IS A CLASS 1a anti arrhythmogenic. It prolongs action potential and is vagolytic. USEL convert them out of afib or vtach. CI: NEVER WITH CHF. SEs include: ataxia, colic, diarrhea, nasal edema (they are obligate nasal breathers GDI), laminitis, sudden death (lol)
**lidocaine: what is the MOA/ what class? What do we use it for? CI/SEs?
Class Ib anti-arrhythmic which shortens the AP. CAREFUL WITH: CHF, liver dz. Can cause hyperexcitability, seizures.
compare class and MOA of quinidine and lidocaine.
QUINIDINE is class 1a and it PROLONGS the AP (hence used to tx fast shit like afib and vtach). Lidocaine is class 1b and it SHORTENS the AP. (hence used to tx fast things like vtach) [[so basically whether you lengthen or shorten the AP it seems to sow the heart-- I assume if the AP is longer it takes longer to get to the next AP. and if you shorten the AP the repol will take longer? That is my best guess]] (maybe this will help: http://www.cvpharmacology.com/antiarrhy/sodium-blockers )
procainamide: what class/MOA? Use? CI/SE?
MOA: Class 1a antiarrhythmic. It prolongs the AP. used to tx vtach. CI: dont use with CHF. SEs are same as with quinidine (Ataxia, colic, diarrhea, nasal edema, laminitis, sudden death** ) but are not as severe
transvenous electrical conversion--> when do we use this? how does it all work?
Basically use this when Quinidine doesnt work (to convert them out of afib or vtach) or when there are too many adverse reactions to the quinidine. There is a high success rate and low incidence of adverse problems, but it does require general anesthesia along with specialized equipment and training. Successful in many horses refractory or post-adverse effects of quinidine. (you are basically shocking heart back into a normal rhythm-- put a tiny taser down the jugular and into the heart
take home rules: if you hear a pathological arrhythmia, you should
look for the underlying cause! super rare for a path one to be a 1* prob
take home message: if you hear a murmur that is a grade II or less....
GENERALLY not pathological
if you need to refer a horse for a heart prob WHAT DO YOU NEED TO TELL THE OWNER?
NO RIDING (unless they like being crushed to death)
which horses tend to get degenerative valve dz- and in which valves?
usually aortic and mitral valves (so, left side). Usually in older/geriatric horses (15+ yrs)
when/why do horses get pericarditis/ what is it?
Pericarditis in association with a pericardial effusion is a rare clinical entity in the horse.Cause: penetrating wounds, extension of infection from adjacent structures, septicemia, neoplasia.CS are of heart dz
what are the Physiologic (non-pathologic) arrhythmias in horses?
2*AV block, sinus block (long pauses) (APCs and VPCs if there is < 3 an hour)
what are really the only 2 right sided murmurs we hear in horses?
VSD and tricuspid insuff
on L side what are the 2 most likely murmurs we will hear and how will you know which is which?
aortic or mitral valve insuff- tell based on if in diastole or systole
what are the Physiologic (non-pathologic) murmurs in horses?
if grade II or less, prolly not pathological. If continuous murmur in a foal under 7 day (PDA), not path.