Today's Veterinary Practice

MAY-JUN 2018

Today's Veterinary Practice provides comprehensive information to keep every small animal practitioner up to date on companion animal medicine and surgery as well as practice building and management.

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29 MAY/JUNE 2018 ‚óŹ TVPJOURNAL.COM CONTINUING EDUCATION Follow-Up Care Over the next 24 to 48 hours as the patient improves, intravenous diuretics are typically transitioned to oral diuretics, often furosemide 2 mg/kg PO q8h initially, with a plan to titrate the dose to q12h after 3 to 4 days. Treatment regimens will vary based on patient response, renal function, and clinician preference and experience. The first recheck appointment is usually at 7 days, although many owners appreciate a phone consultation to check progress after 2 to 3 days at home. At that appointment, thoracic radiographs and blood samples should be taken to confirm resolution of CHF and to check electrolyte and renal status. If the dog is eating normally, electrolytes are usually in the normal range. If hypokalemia is present, potassium supplementation can be added to the treatment regimen. Follow-up visits are usually planned at 1 month and then every 3 months. Owners are strongly advised to record their dog's resting respiratory rate. There are several apps available for smartphones that can help do this. Involving clients in their dog's care and treatment increases client compliance and allows them to recognize when CHF is returning, which will prompt a return to the clinic. Client compliance is extremely important, as the owners will need to medicate their pet daily for the rest of its life and be vigilant for the return of decompensation. CHRONIC TREATMENT OF CONGESTIVE HEART FAILURE Chronic treatment of patients with CHF shifts from trying to control pulmonary edema to trying to negate deleterious effects of neurohormonal stimulation. The aim of chronic CHF treatment is to increase longevity of the patient, as well as improve quality of life. As a result, treatment for chronic CHF generally involves the use of 4 medications: furosemide, pimobendan, an angiotensin-converting enzyme (ACE) inhibitor, and spironolactone. These drugs are usually continued indefinitely. Other drugs may also be required. Standard Regimen Furosemide: The dose can gradually be decreased toward 1 mg/kg q12h, but with each dose reduction the owner should monitor for any change in the dog's respiratory rate and effort. Thoracic radiographs can be helpful to monitor response to therapy, although they often mirror what is anticipated from the respiratory status. Chronically, renal failure may start to develop, especially with escalating doses of furosemide. Ultimately, many patients cannot be kept out of heart failure without using doses of diuretics that induce renal failure. Pimobendan: 4,5 The dose is 0.2 to 0.3 mg/kg PO q12h on an empty stomach, as a recent meal significantly decreases absorption. In cases of refractory heart failure, some cardiologists increase the dose of pimobendan to 0.2 to 0.3 mg/kg PO q8h, although there are no supporting studies. There has been debate regarding whether pimobendan would increase ventricular arrhythmias, increasing the rate of cardiac death, as other phosphodiesterase 3 inhibitors do in humans. However, this has not been supported in clinical trials. 5,6 Indeed, pimobendan has been shown to increase life expectancy when compared to standard therapy. ACE inhibitors have been shown to help in the control of CHF and increase longevity for dogs with DMVD and DCM. Commonly used ACE inhibitors include enalapril and benazepril, while ramipril and quinapril are also available in Europe for dogs. 7-9 All of the modern ACE inhibitors have a similar duration of action and should be used once to twice daily. Often, an ACE inhibitor dose is started once daily and is increased to twice daily as the disease progresses. Enalapril is excreted via the kidneys, whereas benazepril is excreted 50% by the kidneys and 50% by the liver; therefore, benazepril may be preferable in patients with some renal compromise. Typically, an ACE inhibitor is dispensed as the patient is discharged from the hospital with instructions not to start the drug until the patient is eating well. There is always a concern that an ACE inhibitor could exacerbate pre-existing renal failure and starting an ACE inhibitor should prompt evaluation of renal parameters after one week. While blocking the conversion of angiotensin I to angiotensin II, some vasodilation should be seen and systolic blood pressure would be expected to decrease. However, the change is usually about 5 to 10 mm Hg, and it is uncommon for hypotension to be clinically apparent. Indeed, in dogs these drugs are generally well tolerated, improving survival and quality of life. 7,8 Elevated aldosterone levels are very harmful to the myocardium. Angiotensin II is one of the potent

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