Equine Med- Cardio 2

wilsbach's version from 2016-04-03 19:32

Drugs / conclusions

Question Answer
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: )
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 shouldlook 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.

Jeopardy time

Question Answer
3 arrhythmias normal in a horse?2*AV, sinus block, APV/VPC (if < 3 in an hour)
if you ID a horse with afib, what tests should you def run?ECG, CBC/CHEM, echo
what is this arrhythmia and what should you tx it with? This is vtach (fast HR, cant even see P's bc theyre buried under the fast QRSs) .... tx with LIDOCAINE
The intensity of a murmur is not indicative of the severity of the lesion except for with lesions of this valve where the longer and louder the murmur the larger the lesion. Tricuspid (tricuspid is telling you how bad it is)
You examine an apparently healthy 1 day old foal and auscult a grade 4 continuous murmur loudest on the left. You recommend this plan to the owner. (its on the left bc the aorta is on the L, jackass) this is PDA- normal in foals up to 7d, tell them recheck in a week
The way to differentiate between a grade 5 and grade 6 murmur?steth off the chest!!
(review of murmur grades)1) can barely even hear in a silent room- intermittant (2) quiet on one side (3) moderate intensity (4) loud (5) thrill (6) can hear with steth off chest, thrill
Your differential list in a 6 year old TB mare with history of fever & weight loss after ausculting a grade 3 systolic murmur over the left heart apexBacterial endocarditis – mitral valve Myocarditis (was either MI or mitral endocarditis and she is sick, so yeah)
Your diagnosis in a 2 year old Arabian stallion presented to you for poor growth & exercise intolerance with a right sided systolic murmurVSD (systolic. Not a foal so technically could be TI too)
The clinical signs associated with right heart failure(hearts fail backwards) High heart rate, jugular pulse, venous distension, ascites (RARE)
The position of the clamps for a base apex lead in a horse"black heart, red neck (R), White on Right shoudler"
You recommend this additional diagnostic test in a mare in which you suspect bacterial endocarditis based on physical exam and echocardiogram findingsBlood culture
Methods by which you would differentiate a distended jugular vein from a thrombosed jugular veinPalpation +/- ultrasound. Check other vessels and for signs of heart disease
what is this? VSD-- this pic is norm:
The diuretic of choice when exhibiting signs of left or right heart failurefurosemide
General recommendations to the owner of a horse showing signs of heart diseaserefer and do not ride
The side effects of quinidineAtaxia, diarrhea, colic, oral ulceration if given orally, nasal or laryngeal edema, Laminitis, hypotension, decreased contractility, and sudden death
Your treatment options for a horse with a VSDNothing -- Can treat heart disease symptomatically
Your choose these 2 drugs for a horse with signs of heart disease to slow the heart rate, increase contractility and cause vasodilationDigoxin (+ inotrope) & a vasodilator like ACE inhibitors (enalapril) Or hydralazine – arterial dilator
These 2 valves are most commonly affected by degeneration and endocarditisAortic and mitral (L side, horse has a crazy amount of L sided work being a horse and all)
5 reasons why a horse’s heart rate may be elevatedPain, excitement, stress, exercise, heart disease, white muscle disease, toxicity like monensin or cantharidin
Of the 6 grades of murmurs, the grade described as: “Very soft focal murmur only detected in a quiet area after extended auscultation” grade 1
The 4 mechanisms of edema formationDec oncotic pressure, inc hydrostatic pressure, lymphatic obstruction, inc vascular permeability
4 reasons why a horse’s heart sounds could be muffledFat, Pleural or pericaridial fluid, Pneumothorax , Abscess/tumor
5 specific causes of myocardial diseaseBacterial/Viral: Staph, strep, clostridium (With endocarditis or pericarditis) EIA, EVA, Influenza. -Vitamin E/sel def, gossypol, cassia ingestion, monensin toxicity, cantharidin