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Volume 15, Number 05 American College of Veterinary Pharmacists
MANAGEMENT OF CARDIOVASCULAR DISEASE
IN THE HOUSEHOLD DOG
or it may be from dramatically in- riosus (PDA) or Tetralogy of Fallot, As awareness of cardiovascular dis- creased afterload such as chronic pul- and are therefore not included in this ease increases in human medicine, monary hypertension. Even though newsletter as the focus is primarily on there is now a trend of increasing diastolic and systolic functions of the pharmacologic management. awareness within veterinary medicine heart are related, both tend to be com-
as well. This ACVP newsletter will
prised in animals with myocardial focus on the most common forms of disease. The more veterinarians are The heart is essential for operation cardiovascular disease and their treat- learning about CVD, the more docu- of the circulatory system via ejecting ments in dogs with a following news- mentation is being recorded about the blood into the aorta and pulmonary letter on heart disease in cats in order prevalence of certain breeds correlat- arteries meeting perfusion require-to make this reading more succinct. ing with specific forms of CVD. One ments of metabolic tissues. It also The availability of information on this example of heart failure is Dilated receives blood from the pulmonary topic can be overwhelming so an Cardiomyopathy (DCM) which pri- and systemic veins in order to drain overview of cardiovascular disease marily affects large breed dogs such capillary beds and maintain appropri- and the medications used to manage it as Dobermans, Irish Wolfhounds, ate distribution of the circulating will be assessed in this article, hope- Great Danes, and Newfoundlands, but blood volume. Cardiac performance fully creating a better understanding also male Dalmatians and American is essentially determined by stroke for veterinarians about which agents and English Cocker Spaniels. Of volume and cardiac output including are most appropriate for their patients these dogs, 50% will develop the ar- preload, after load, heart rate, myo- depending on which type of heart dis- rhythmia Atrial Fibrillation (AFib). cardial contractility, and ventricular ease they suffer from. Arrhythmogenic Right Ventricular synchrony. Alteration of any of these Cardiomyopathy (ARVC) appears to operations can lead to cardiac dys-be exclusively represented by the function. Cardiac failure (i.e. heart Boxer breed which is why it is also failure) is defined as the physiologic known as Boxer Cardiomyopathy. state in which the heart cannot eject On the other hand, Myxomatous Mi- tral Valve Disease (MMVD), which makes up 75% of canine congestive Sand Run Pharmacy heart failure, is prevalent in smaller breeds such as Cavalier King Charles Spaniels, Papillons, Chihuahuas, Dachshunds, and Toy Poodles. This disease normally affects older dogs Prevalence
with the exception of Cavaliers and Hours of Operation Cardiovascular disease (CVD) is Dachshunds who may experience on- not just a condition that affects hu- set of this disease as early as 2 to 4 mans, but our four legged patients as years of age. As with humans, there well! Heart disease may be due to are also many congenital heart dis- impaired cardiac filling as seen with eases, but these are often surgically mitral and tricuspid valvular stenosis corrected, such as Patent Ductus Arte-

4. Heart failure resulting from ar- creased blood flow to critical organs or receive blood properly resulting in rhythmias and conduction disor- and if not medically managed, will manifestation of erratic blood volume eventually lead to death. homeostasis and clinical signs and a. sustained tachyarrhythmias symptoms of heart failure. If cardiac such as supraventricular Summary of Clinical Signs
dysfunction causes an accumulation tachycardia and atrial fibrilla- 1. New onset lethargy of sodium and water, edema and con- 2. Decreased interest in food gestion result in clinically recognized b. chronic bradyarrhythmias such 3. Exercise intolerance congestive heart failure (CHF). The as complete heart block 4. Coughing or wheezing four main functional classifications of Since there are so many nuances 5. Increased panting veterinary heart failure per the Text- involved with CVD, and this newslet- 6. Edema book of Veterinary Internal Medicine ter  isn't  meant  to  be  a  textbook  on   7. Cyanotic membranes cardiology, these functional classifi- 8. Episodes of unexplained syncope 1. Heart failure resulting from im- cations will be further examined from 9. Orthopnea peded cardiac filling a treatment perspective. a. pericardial disease with Diagnosis
restricted filling such as Clinical Signs and Symptoms
The primary means of diagnosing a constrictive pericarditis or There are many signs and symp- dog with cardiovascular disease is pericardial effusion with tam- toms of CVD depending on which through a complete history and thor- type of heart disease the dog is af- ough physical exam, followed by ra- b. valvular inflow obstruction flicted with. Commonly dogs will diographs, electrocardiogram, and/or such as AV valve stenosis or present with exercise intolerance, an echocardiogram. A CBC and neoplastic anatomic obstruc- dyspnea, coughing, pitting edema, Chemistry Panel may be useful for lethargy, cyanosis of the membranes, identifying and/or ruling out other c. intrinsic myocardial disease and may also experience consistent or disease processes such as diabetes, with impaired diastolic func- intermittent syncope. Mitral valve pancreatitis, renal disease, or an un- tion such as hypertrophic regurgitation will often present in a derlying infection. Chest radio- cardiomyopathy or restrictive young male Cavalier with coughing, graphs, an electrocardiograph, and/or cardiomyopathy labored breathing, and exercise intol- an echocardiograph present the prac- 2. Heart failure resulting from in- erance. A depressed, coughing, exer- titioner with an even better under- creased resistance to ejections cise intolerant Doberman with a standing to what is, or is not, auscul- a. increased resistance to the rapid, irregular heart beat is likely to tated on physical exam. It is very ejection of blood (after load) have DCM. Sick sinus syndrome important to discuss with the owner such as thromboembolism of often presents in a middle age female about when they noticed changes in great vessels, pulmonary hy- Miniature Schnauzer that has inter- their pets behavior and keeping good pertension, or discrete out- mittent fainting yet a Boxer who also records of when any of these changes flow tract obstruction faints is likely to have arrhythmic become more noticeable with regards 3. Heart failure resulting from im- cardiomyopathy. These problems, if to time of day or in relation to certain paired ejection or volume over- not addressed right away by a veteri- activities. narian, can become life threatening a. primary and secondary myo- just as they would in a human. Car- Diagnostic Algorithm
cardial disease with impaired diovascular disease can lead to pul- 1. Assess history, physical exam, systolic function such as di- monary edema, renal failure, de- and clinical signs lated cardiomyopathy or a. Auscultation of the heart and ischemic, infectious, or toxic lungs and assessment of myocardial disorders b. misdirected blood flow re- i. Detect abnormal sounds sulting in volume overload such as a gallop, mur- such as valvular insufficiency or arteriovenous fistulas ii. Heart beat that is muffled c. chronic high-output as an indication of peri- states such as thyrotoxicosis cardial effusion in ab- or chronic anemia sence of obesity iii. Detect tachycardia or

e. Detecting pericardial disease tensin I to angiotensin II which results in vasodilation since angiotensin II iv. Observe rapid, irregular, stimulates aldosterone that normally causes sodium and water retention b. Mucous membranes cyanotic that cause congestion and edema. in absence of primary pulmo- ACEi's  also  contribute  to  vasodilation   by increasing concentrations of vaso- c. Determine from owners about dilating kinins and prostaglandins. when the change in behavior Commonly  used  ACEi's  in  dogs  are   benazepril, enalapril, and lisinopril 2. Rule out iatrogenic disease though captopril may also be used but a. Current or past medications Diagnostic Tests
it is older and its use has decreased. b. Exposure to possible house- In order to increase quality of life Ramipril is a newer ACEi and has not hold toxins (plants, owner and  extend  the  patient's  overall  sur-­ been studied as much in animals but medications, household vival, medical treatment must be im- appears to have similar pharmacody- plicated as soon as possible. Diag- namic effects. Benazepril may de- 3. Preliminary Lab Results nostic testing should be performed to crease the likelihood of developing better understand which form of CVD cardiomyopathy in some dogs but i. Identify a possible the animal is experiencing in order to studies on this are controversial. underlying infection treat and alleviate symptoms and de- Enalapril is also useful to delay the b. Chemistry Profile crease chances of morbidity and mor- onset of CHF in dogs with mitral re- i. Serum chemistry gurgitation and is often used with di- profiles may identify a goxin, furosemide, pimopendan, and comorbid disease state 1. Thorough history and physical spironolactone. The dose of such as diabetes or renal exam with auscultation of heart benazepril is 0.25-0.5 mg/kg by mouth every 12 to 24 hours. The dose of captopril in dogs is 1-2 mg/kg a. Identify mitral regurgitation or 3. Chemistry Panel by mouth every 8 hours. The dose of dilated cardiomyopathy enalapril in dogs is 0.5 mg/kg every b. Detect the degree of 12 to 24 hours by mouth. The dose of enlargement of pulmonary lisinopril in dogs is 0.5 mg/kg by mouth once daily. The dose of rami- 5. Electrocardiography (ECG) Treatment
pril is 0.125-0.25 mg/kg by mouth a. Measures electrical impulses There are several drug classes avail- once daily. Benazepril, enalapril, lisi- via electrical leads to observe able for veterinarians to manage CVD nopril, and ramipril are generally well patterns among heartbeats and in their patients and each class is spe- tolerated though they can cause az- rhythms cific to where in the heart the problem otemia in at-risk patients, especially b. Diagnose rhythm disturbances is occurring. Because of the intrica- those on high doses of diuretics. All i. Atrial Fibrillation cies of cardiovascular disease, the ACEi's  are  contraindicated  for  preg-­ ii. Sick Sinus Syndrome choice of therapy, or therapies, must 6. Echocardiography (Echo/TTE) be individualized to the afflicted ani- a. Ultrasound waves or Doppler mal specifically. Within each drug Antiarrhythmic Agents techniques to produce images class are often specific medications There are actually 4 groups of drugs that may be chosen over another due within this class. The first medica- b. Can confirm tentative diagno- to safety, comorbid disease states, tions discussed are disopyramide and side effects, and cost. quinidine which are class 1a antiar- c. Detect enlargement of rhythmics that block inward fast so- chamber of the heart and large ACE Inhibitors dium channels and depress myocar- Angiotensin-converting enzyme dial Phase 0 of depolarization to pro- i. Usually more severe action potential duration in order cations that are typically used to treat to control ventricular arrhythmias. enlargement, the more hypertension and congestive heart Efficacy studies of disopyramide in the disease severity failure. Their mechanism of action is animals have not been reported and it d. Detecting cardiac tumors to inhibit the conversion of angio- has a very short half-life in dogs. It is also a Class III antiarrhythmic as thy, and anemia. Dobermans appear being included for sake of complete- well. Its action is similar to pro- especially affected by amiodarone ness. The dose is 7-30 mg/kg by pranolol but also has some potassium experiencing high levels of anorexia, mouth every 4 hours and side effects channel blocking activity. Similar to lethargy, hepatic toxicity, and vomit-have not been specifically reported in atenolol, it is more water soluble and ing. Class IV antiarrhythmics are the dogs though in humans adverse reac- relies less on the liver for clearance. non-dihydropyridine calcium channel tions are secondary to this medica- This medication is indicated for the blockers and due to their unique phar- tion's  anticholinergic  effects  such  as   management of refractory ventricular macologic mechanism, will be dis-constipation and dry mucous mem- arrhythmias and refractory atrial fib- cussed in another section. branes. At higher doses it can induce rillation. The dose is 1-2 mg/kg by arrhythmias in human patients. mouth every 8 to 12 hours though Beta Blockers Quinidine has the same mechanism of with medium to large breed dogs, These medications work to block action as a Class Ia but can also be typically clinicians begin with 40 mg beta-adrenergic receptors in order to used to convert atrial fibrillation to per dog every 12 hours and increase slow the heart rate and are used to sinus rhythm (NSR). The dose of to 80mg if no response is noted. Side treat supraventricular tachyarrhyth- quinidine gluconate is 6-20 mg/kg effects include dyspnea, broncho- mias and premature ventricular con- every 6 hours IM or by mouth while spasm, nausea, vomiting, and pro- tractions. Choices for use in dogs the conversion from AFib to NSR is 6 arrhythmic activity. Amiodarone is a include atenolol, propranolol, and -11 mg/kg IM every 6 hours and most Class III antiarrhythmic and its metoprolol. While carvedilol, selec- dogs will convert within 24 hours. mechanism of action is to block the tive for β1,  β2,  and α  receptors, has Side effects include nausea, vomiting, outward potassium channels in car- been very successful in humans for diarrhea, hypotension, tachycardia, diac tissues. It also prolongs the ac- heart failure, its absorption in dogs is and AV block. Class Ib consists of tion potential and delays both myo- very unpredictable and therefore its lidocaine, phenytoin, mexelitine, and cardial repolarization and refractory use is not recommended. Atenolol is tocainde, and they block fast sodium period in the cardiac tissues. It is selective for β1  though at higher channels and depress Phase 0 of de- used to treat refractory ventricular doses β2  blockade can occur. polarization to treat ventricular ar- arrhythmias and is reserved for life- Metoprolol tartrate is also relatively rhythmias. Lidocaine, though the threatening arrhythmias refractory to selective for β1  though at higher most likely to be used for acute ven- the treatments. Usually a loading doses it can exhibit some β2  block- tricular arrhythmias, would not be dose is given followed by a mainte- ade. Propranolol is non-selective and sent home with a patient and is there- nance dose and proper monitoring targets β1  and β2  in the myocardium, fore will not be discussed in this arti- such as ECG and CBC should be per- bronchi, and vascular smooth muscle cle. Phenytoin has poor efficacy and formed while the dog is on this treat- and has membrane stabilizing activ- questionable absorption but if used ment due to the array of side effects. ity. Both metoprolol and propranolol the dose is 30 mg/kg by mouth every An example of an amiodarone dosing are lipophilic and therefore cross the 8 hours. Side effects are sedation, regimen for ventricular arrhythmias is blood brain barrier. The dose of at- gingival hyperplasia, skin reactions 10-15 mg/kg by mouth every 12 enolol in dogs is 6.25-12.5 mg per and  CNS  toxicity.    Mexiletine's  use   hours for 1 week then 5-7.5 mg/kg by dog by mouth every 12 to 24 hours or in veterinary medicine is also not mouth every 12 hours for 2 weeks, 0.5-1 mg/kg by mouth every 12 to 24 common but its dose is 5-8 mg/kg by then 7.5mg/kg by mouth every 24 hours. The dose of metoprolol tar- mouth every 8 to 12 hours. Side ef- hours. An example of a dosing regi- trate in dogs is 0.25-1 mg/kg by fects include excitation, tremors, and men for atrial fibrillation is a 15 mg/ mouth every 12 to 24 hours. The vomiting. Tocainide also has limited kg by mouth loading dose for 5 days dose of propranolol in dogs is 0.1-0.2 use in animals but clinical studies do followed by 10 mg/kg by mouth once mg/kg by mouth every 8 hours. demonstrate efficacy. The dose is 15- daily thereafter. If you must use this These medications can cause extreme 20 mg/kg by mouth every 8 hours and medication in a Boxer or Doberman, bradycardia and heart block which is side effects include anorexia, vomit- the dose is 200mg by mouth every 12 why  often  times  the  phrase  "start  low   ing, and ataxia. Class II antiarrhyth- hours for 1 week then 200 mg by and  titrate  slow"  is  heard  from  phar-­ mics are the Beta Blockers but due to mouth once daily thereafter. Side macists and when discontinuing ther- their limited use for heart failure spe- effects include decreased appetite, apy, institute a gradual tapering down cifically, they are discussed later on prolongation of the QT interval, bra- regimen. The non-selective beta with the exception of sotalol. Sotalol dycardia, CHF, hypotension, AV blockers, such as propranolol, may is unique in that it is a Class II antiar- block, pulmonary fibrosis, neutro- produce bronchospasms in certain rhythmic beta blocker (β1,  β2)  but penia, thyroid dysfunction, hepatopa- patients since β  receptors occur in for supraventricular tachyarrhythmias ing on which veterinary cardiologist lung tissue as well cardiovascular tis- is 0.5-1.5 mg/kg by mouth every 8 you speak with or which literary sue. These medications can also hours. The dose for diltiazem for source you refer to. For heart failure cause lethargy and mask clinical signs atrial fibrillation when used with di- alone the starting dose is 0025-.005 associated with hypoglycemia so use goxin (0.0005 mg/kg BID) is 3 mg/kg mg/kg by mouth every 12 hours. For these judiciously in patients with dia- by mouth every 12 hours. Verapamil CHF in the presence of AFib, the betes. In any patient with overt heart is generally given IV as oral formula- dose is 0.005-0.0075 mg/kg by mouth failure, greater than 1st degree heart tions are not absorbed sufficiently and every 12 hours. It is a narrow thera- block, or sinus bradycardia, these for this reason diltiazem is generally peutic index drug and has the ability medications are contraindicated. The preferred in veterinary patients. Nev- to cause a variety of unwanted ar-exceptions to this CHF rule are ertheless, the initial dose is 0.05 mg/ rhythmias if not dosed correctly. For metoprolol succinate, bisoprolol, and kg IV every 10-30 minutes for a max these reasons it is appropriate to carvedilol but these are rarely used in cumulative dose of 0.15 mg/kg and monitor serum digoxin concentrations veterinary medicine and are only the oral dose, per literature, is 1-5 mg/ in your patient to determine optimum mentioned for sake of completeness. kg by mouth every 8 hours. Side ef- therapy. In dogs, the therapeutic fects generally include bradycardia, range is 1-2 ng/ml approximately 8 to Calcium Channel Blockers lethargy, GI distress, AV block, hy- 10 hours after a dose for treating atrial potension, rashes, or elevations in fibrillation while a more tightly con- Dihydropyridine calcium channel liver function tests. Diltiazem is con- trolled level of 0.8-1.2 ng/ml is rec- blockers, amlodipine and nifedipine, traindicated in patients with severe ommended for treating heart failure in are a group of medications that block hypotension (<90 mmHg systolic), the presence of AFib or DCM. A calcium channels and also act as sick sinus syndrome, or 2nd/3rd degree maximum level is 2.5 ng/ml is recom- vasodilators. They decrease calcium AV block and should be used with mended as adverse events are noted influx in cardiac as well as smooth caution in dogs with heart failure. above this dose. While determining muscle and are normally used to treat the ideal dose, a patient can be moni- systemic hypertension and are often Cardiac Inotropic Agents tored with an ECG to detect digoxin used in combination with a beta The first group of medications in induced adverse arrhythmias. It can blocker. The initial dosing for am- this drug class are digitoxin and di- also cause such side effects as vomit- lodipine in dogs is 0.1 mg/kg by goxin, though only digoxin is avail- ing, anorexia, and diarrhea. Dober- mouth every 12 to 24 hours. The able in the USA. Digoxin, which mans appear to be most sensitive to dose for nifedipine in animals has not originates from the Foxglove plant, these adverse effects. It is also im- been established. Side effects include acts as a cardiac inotropic agent. This portant to note that high levels of po-hypotension and bradycardia though a means that it increases cardiac con- tassium  will  decrease  digoxin's  clini-­ few cases of gingival hyperplasia tractility while also decreasing heart cal effects and low potassium will have been observed in dogs. rate via suppression of the AV node enhance its effects leading to toxicity. to inhibit re-entrant cardiac arrhyth- The second group in this class con- Calcium Channel Blockers (non- mias.    This  medication's  complicated   sists of one drug that functions as a dihydropyridine) mechanism of action revolves around positive inotrope and vasodilator These calcium channel blockers, its ability to inactivate cardiac muscle (inodilator), pimobendan, for use of diltiazem and verapamil, are non- sodium-potassium ATPase and in- the management of congestive heart dihydropyridines and will block cal- crease intracellular calcium. It also failure and either valvular insuffi- cium entry into cells by blocking volt- has neuroendocrine effects that in- ciency or cardiomyopathy. This age-dependent slow calcium chan- clude sensitization of baroreceptors to medication inhibits phosphodiesterase nels. This results in vasodilation, decrease heart rate via increasing va- III and increases intracellular concen- negative chronotropic effects, and gal tone. Its use in dogs for the treat- trations of cAMP and may inhibit negative inotropic effects with a pre- ment of heart failure is due to its posi- some phosphodiesterase V in the pul- dominant effect on the SA and AV tive inotropic effects and also for its monary circulation. Its inotropic ef- node. These are used for many rea- ability to decrease heart rate. It can fects are due to its action as a calcium sons such as control of supraventricu- also be used to decrease ventricular sensitizer to increase troponin C with lar arrhythmias, systemic hyperten- response for supraventricular arrhyth- contractile proteins. The dose is 0.25- sion, hypertrophic cardiomyopathy, mias as it suppresses the AV node. It 0.3 mg/kg by mouth every 12 hours. atrial flutter, AV nodal re-entry ar- is often used in combination with an Side effects include anorexia, leth- rhythmias, and other forms of tachy- ACEi and a diuretic such as fu- argy, diarrhea, dyspnea, azotemia, cardia. The chronic dose of diltiazem rosemide. The dose is varied depend- weakness, pleural effusion, syncope, group of diuretics mentioned in this tion, and tolerance that can develop sudden death, and ascites. This medi- newsletter are the potassium-sparing with  repeated  use.    It's  very  important  cation also has the potential risk to be diuretics, specifically spironolactone to advise owners to apply this medi-arrhythmogenic, and if furosemide is and triamterene, which interfere with cation with gloves! Irbesartan and added, then some activation of the sodium reabsorption in the distal renal losartan are another group of vasodi- renin angiotensin aldosterone system tubule by competitively inhibiting the lators that function as angiotensin may occur. action of aldosterone and are used to receptor blockers (ARB). The me- treat congestion caused by heart fail- tabolism of these medications in dogs Diuretics ure and are often used with an ACEi. is uncertain and it appears that losar- Furosemide is a loop diuretic that The difference between them is that tan, another ARB, does not show ef- exhibits its mechanism of action by triamterene does not have the com- fect in dogs since it does not produce inhibiting the sodium-potassium- petitive inhibiting effect on aldoster- an active metabolite. On the other chloride co-transporter in the ascend- one and for treating congestive heart hand, irbesartan does appear to func-ing loop of Henle to decrease the so- disease in animals, spironolactone is tion though due to cost, it is rarely dium, chloride, and potassium reab- more frequently used. However, the used  and  ACEi's  are  used  instead.     sorption from the tubule. It is the dose of triamterene is 1-2 mg/kg by The dose of irbesartan is 30-60 mg/kg most effective of the diuretics and mouth every 12 hours. The dose for by mouth every 12 hours and side creates very dilute urine. Furosemide spironolactone is also 1-2 mg/kg by effects are minimal and limited to also increases intrarenal prostaglandin mouth every 12 hours. Side effects of hypotension. production via PGI2 to increase renal both include electrolyte abnormalities blood flow which causes vasodilation (especially hyperkalemia), dehydra- Prognosis
in other tissues. One of its uses in tion, anorexia, vomiting, lethargy, and Cardiovascular disease, once pre- dogs is to treat edema cause by heart ataxia. sent, will remain a lifetime complica- disease. The dose is 2-6 mg/kg every tion for your patient. If your patient 8 to 12 hours either IV, IM, SQ or Vasodilators has an arrhythmia, the prognosis is PO. A common starting dose though Hydralazine is a vasodilator and slightly more grim. When an arrhyth- for heart failure dogs is 2 mg/kg by antihypertensive agent that relaxes mia is detected on routine examine, a mouth every 12 hours then lower to 1- vascular smooth muscle in arteriolar Holter monitor may be worn so that 2 mg/kg by mouth every 12 hours. vascular beds and helps reduce vascu- that veterinarian may interpret the Adverse effects are related to its diu- lar resistance and improve cardiac results and evaluate the frequency and retic effects such as loss of fluid cre- output. The mechanism by which it complexity of the arrhythmia over the ating dehydration and electrolyte dilates arterioles and decreases car- course of 24 hours. Pimobendan has losses. Another group of diuretics are diac afterload is not exactly under- demonstrated a 4 month survival ver- chlorothiazide and hydrochlorothi- stood but it is used primarily for treat- sus placebo in Dobermans with DCM azide, thiazide diuretics which are ment of CHF, valvular heart disease, while Fish Oil in Boxers has demon- really just mentioned for sake of com- and other CVD that has high periph- strated some improvement in ven- pleteness as these are not used very eral vascular resistance. The dose is tricular premature contractions often in veterinary medicine as they 0.5 mg/kg by mouth once daily ti- (VPC's)  and  a  decrease  in  syncopal   are sulfonamide analogs and their trated up to 0.5-2 mg/kg by mouth episodes but not a decrease in mortal- pharmacokinetics are not well de- once to twice daily. Side effects in- ity. For heart failure in the absence of scribed in animals. Their mechanism clude hypotension and dangerously arrhythmias, the outlook is slightly of action is to inhibit the sodium- reduced cardiac output. Nitroglycerin more encouraging. Management fo- chloride cotransporter in the luminal is another vasodilator, specifically a cuses on enhancing quality of life by side of the distal tubule therefore nitrovasodilator used for heart failure improving clinical signs and increas- leading to sodium and water diuresis of pulmonary edema. Its mechanism ing survival. Prognosis depends on but these medications have far less of of action is to relax vascular smooth how the patient presents and what a diuretic effect than furosemide. The muscle via generation of nitric oxide. stage they are per the New York dose for chlorothiazide is 20-40 mg/ The dose is 4-12 mg topically every Heart Association and International kg by mouth every 12 hours. Hydro- 12 hours or the owner may apply ½ Small Animal Cardiac Health Council chlorothiazide is dosed at 2-4 mg/kg inch of 2% ointment for every 5 guidelines. If they have asympto- by mouth every 12 hours. Side ef- pounds of body weight to skin with- matic myocardial disease and are fects are limited to electrolyte imbal- out hair (i.e. pinnae of ear or axilla) treated right away, then likely they ance and perhaps reactions in animals every 8 hours. The primary side effect have many years left with their fami-allergic to sulfonamides. The third is hypotension, rash at site of applica- lies. However, those dogs that have

enolol and enalapril are financially holm: Wiley-Blackwell, 2011. severe and fulminant heart disease, within the budget while pimobendan 7. www.Merckvetmanual.com. Car- often requiring oxygen therapy, sur- is just too costly. Pharmacists can diovascular Drugs. 2011. vival may only be a few months and work with veterinarians in order to 8. Google Images. June 2012. euthanasia may even be the most hu- evaluate the best treatment protocol 9. Atkins C, Bonagura J, Ettinger S, which will properly medicate the pa- et al. Guidelines for the Diagno- tient and also financially benefit their sis and Treatment of Canine owners. It is also important to con- Chronic Valvular Heart Disease. J sider dosing intervals; owners that Vet Intern Med. 2009;23:1142– work may only be able to give once or twice daily dosing. Being suppor- 10. www.heart.org for New York tive and counseling on the various Heart Association. June 2012 classes of cardiovascular medications 11. International Small Animal Car-to the best of our ability is critical in diac Health Council. earning and keeping our owners trust! Appendix 1: Recommendations for the diagnosis of heart disease For Further Reading
and treatment of heart failure in Role of Veterinary Pharmacist
1. Sisson DD. Cardiovascular Sys- small animals. In: Tilley LP, Treating pets with cardiovascular tem. In: Ettinger SJ, Feldman EC. Goodwin JK, eds. Manual of ca- disease offers a unique opportunity Textbook of Veterinary Internal nine and feline cardiology. 3rd for veterinary pharmacists as many of Medicine. 7th ed. St. Louis: Saun- ed. Philadelphia: the aforementioned products must be ders Elsevier, 2010; 1143-1394. WB Saunders Co, 2001;459–489. compounded because they are not 2. O'Grady  MR,  Minors  SL,   12. Martin MW, Stafford MJ, Streh- palatable or in a dose properly con- O'Sullivan  ML,  et  al.    Effect  of   lau G, et al. Canine dilated car- centrated for our patients. While pi- pimobendan on case fatality rate diomyopathy: a retrospective mobendan is approved for veterinary in Doberman Pinschers with con- study of prognostic findings in use and comes in chewable tablets, gestive heart failure caused by 367 clinical cases. J Small Anim others such as atenolol and fu- dilated cardiomyopathy. J Vet Pract. 2010;51(8):428-36. rosemide do not. Often these heart Intern Med. 2008;22(4): 897-904. failure patients experience polyphar- 3. Fuentes VL, Corcoran B, French macy and pharmacists have the ability A, et al. A double-blind, random- to address drug compatibility issues. ized, placebo-controlled study of Veterinary pharmacists can even pimobendan in dogs with dilated combine medications into one accept- cardiomyopathy. J Vet Intern able dosage form improving compli- Med. 2002;16(3):255-61. ance making life much easier for 4. Smith CE, Freeman LM, Rush owners and their pets. In addition to JE, et al. Omega-3 fatty acids in making compounded medications, Boxer dogs with arrhythmogenic veterinary pharmacists also need to right ventricular cardiomyopathy. provide proper counseling on how to J Vet Intern Med. 2007;21(2):265 administer these medications, such as This article was submitted by: gloves with nitroglycerin, and what 5. SerfassP,Chetboul V, Sam- Jessica Gaskins, PharmD side effects to look for like gingival pedrano CC. Retrospective study North Carolina State University hyperplasia with amlodipine admini- of 942 small-sized dogs: Preva- College of Veterinary Medicine stration. When dispensing digoxin if lence of left apical systolic heart Veterinary Pharmacy Resident the owner is reporting side effects of murmur and left-sided heart fail- anorexia and diarrhea in their dog, the ure, critical effects of breed and veterinary pharmacist may contact the sex. J Vet Cardiol. 2006;8(1):11- referring DVM to see if the most re- cent digoxin levels are therapeutic or 5. Papich M. Saunders Handbook of perhaps the patient does need to come VeterinaryDrugs. 3rded.St. Lois: in to have a new blood level drawn. Elsevier-Saunders, 2011. Cost is another area veterinary phar- 6. Plumb DC. Plumb's  Veterinary   macists must consider. Perhaps at- Drug Handbook. 7th Ed. Stock-

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