/// QUARTERLY BEAT / JULY 2022
QUARTERLY BEAT / JULY 2022 ///
HELPING DOGS WITH MMVD THROUGH NUTRITIONAL MANAGEMENT Current ACVIM guidelines recommend mild sodium restriction beginning in stage B2 and modest sodium restriction beginning in Stage C for dogs with cardiac disease. 1 However, very low sodium diets can actually do more harm than good, stimulating the renin- angiotensin-aldosterone system (RAAS) and releasing aldosterone in high amounts that are detrimental to the heart. This worsens systolic function in the ventricles and causes cardiac fibrosis. 4 Today, we have new nutritional strategies to employ to help manage dogs in the very early stages of MMVD . This approach has the potential to help dogs earlier by supporting cardiac function, reducing left atrial enlargement, and stabilizing mitral regurgitation. CLINICAL STUDY SHOWS EFFICACY OF A CARDIAC-FOCUSED DIET Despite studies showing the benefits of many nutrients in promoting heart health, nutrition has often been overlooked in the management of pets with heart disease—particularly the notion of employing nutrition earlier in the disease process. For example, as noted above, current ACVIM guidelines recommend that nutritional management for dogs with mitral valve disease begin in stage B2, when there are no clinical signs of heart failure but when dogs do have a left apical systolic murmur—likely with an intensity of at least 3/6—and significant cardiac remodeling. Now, research from Purina indicates a proprietary blend of nutrients including amino acids, omega-3 fatty acids, magnesium, vitamin E and medium-chain triglycerides can be fed in stage B1, when dogs have a detectable heart murmur but no or limited evidence of cardiac remodeling. The goal in feeding this nutrient blend is to slow disease progression in dogs with early mitral valve disease. As a result of this research, Purina scientists developed the Cardiac Protection Blend (CPB)—a combination of nutrients found in Purina® Pro Plan® Veterinary Diets CC CardioCare™ Formula diets. Together, these nutrients could help make a positive difference in dogs in the early stages of the disease (see Figure 1). A six-month dietary study 5 demonstrated the effectiveness of a diet containing the CPB in: 1. Addressing the metabolic changes that occur in early mitral valve disease 6 2. Helping reduce left atrial enlargement 5 3. Helping stabilize mitral regurgitation 5 4. Slowing the progression of mitral valve disease in dogs at early stages 5 In the study, 19 dogs with stage B1 or B2 mitral valve disease, as established by ACVIM consensus guidelines, and 17 age-, sex-, body condition- and breed-matched healthy dogs were enrolled.
In each group, half the dogs were randomly designated as control diet dogs while the other half were fed the CPB diet for six months. Both diets were formulated to provide complete and balanced nutrition for adult dogs. The nutrient profiles were similar between the two diets, except for the addition of the Cardiac Protection Blend to the CPB diet. Key findings revealed: • Improved mitral regurgitation in 30% of CPB-fed dogs with early-stage mitral valve disease • Increased serum omega-3 and decreased omega-6 fatty acid concentration s to help nutritionally manage dogs with cardiac conditions • Increased serum arginine and citrulline (precursors of nitric oxide) to promote vasodilation • Improved energy use as signified by biomarkers of fatty acid oxidation FIGURE 1. CARDIAC PROTECTION BLEND COMPONENTS
SPONSORED ARTICLE
Can Diet Reshape Early Intervention for Dogs with Myxomatous Mitral Valve Disease?
SHERRY SANDERSON , BS, DVM, PHD, DIPL ACVIM (SAIM AND NUTRITION) University of Georgia College of Veterinary Medicine
In this VETgirl online veterinary continuing education feature article sponsored by Purina® Pro Plan® Veterinary Diets, Sherry Sanderson, BS, DVM, PhD, Dipl ACVIM (SAIM and Nutrition), discusses myxomatous mitral valve disease (MMVD) in canine patients. She also talks about new research from Purina that reveals early nutritional intervention may slow the progression of mitral valve disease in dogs at early stages.
Nutrient
Benefits
We’re all used to seeing dogs display boundless energy: jumping, running and fetching. It’s this unbridled enthusiasm for life that endears them to millions of people. Sadly, many dogs with advanced heart disease aren’t able to maintain this level of activity. Clinical signs for dogs with late stage myxomatous mitral valve disease (MMVD, or mitral valve disease) include exercise intolerance, increased respiratory rate and unproductive coughing, as well as non-specific signs like lethargy and inappetence. Heart disease is one of the most common disorders of dogs , affecting 1 in 10 canine patients seen in primary care practices. 1 Mitral valve disease is also the most common canine heart disease in many parts of the world, accounting for approximately 75% of heart disease cases seen in dogs by veterinary practices in North America , with the highest incidence noted in older, small- to medium-sized dogs weighing less than 20 kilograms. 1 In dogs with MMVD, the mitral valve progressively degenerates, leading to an enlarged left atrium and ventricle, a less-efficient heart and the risk of congestive heart failure (CHF). Although the majority of dogs with mitral valve disease are not—and never will be—in heart failure, about 30% go on to develop end-stage disease. 2 When we first hear a heart murmur in a dog with mitral valve disease, we typically note it, tell owners that it’s present and recommend diagnostics such as echocardiogram. If the disease progresses, we may add medications like pimobendan to help facilitate disease management. Historically, nutrition has received little attention in the management of canine cardiac
disease beyond a general recommendation that patients avoid high-sodium diets. MEETING THE HEART’S ENERGY NEEDS The hearts of healthy dogs derive the majority of their energy needs from long-chain fatty acids (LCFAs) in the diet. Carnitine is required to get fatty acids into the mitochondria inside the cell to generate energy. However, as mitral valve disease advances, mitochondria become less efficient at using LCFAs as a substrate. One way we can supplement this energy loss is to add medium-chain triglycerides (MCTs) in the C8 and C10 range into the diet. MCTs are a source of medium-chain fatty acids (MCFAs), which the heart can use for energy production. MCFAs do not require a carnitine transporter to get into the cardiomyocyte mitochondria and are easily oxidized to produce adenosine triphosphate (ATP). They can also be converted into ketones by the liver, which are used by the heart muscle as well. So MCTs serve as an alternate energy source for cardiomyocytes, which enhances mitochondrial function and reduces the risk for oxidative stress. Dogs with advanced heart disease can also develop cardiac cachexia and lose muscle mass. To help combat this, we need to ensure their diet has adequate levels of protein to help offset some of the catabolism of lean muscle mass. At least 25% of calories for healthy senior dogs should come from protein. 3 As heart disease advances, especially if dogs are on medications, it is not uncommon for them to sometimes feel unwell and to develop food aversion. This makes it imperative to feed them a highly digestible and palatable diet to help ensure adequate calorie intake.
Synthesized from the precursor amino acids lysine and methionine, carnitine is important for generating energy in the heart and transporting long-chain fatty acids into mitochondria. Taurine aids myocardial osmoregulation, calcium modulation, inactivation of free radicals, mitochondrial functional support and ATP production. It’s the most abundant free amino acid in the heart. EPA and DHA reduce inflammatory mediators, stabilize cardiac arrhythmias, reduce blood pressure and thrombosis, reduce cardiac remodeling in heart disease and reduce the risk of cardiac cachexia. Magnesium is a cofactor in many different enzymes in the body. It’s required for protein synthesis and energy production and reduces inflammation and oxidative stress. Dietary vitamin E is a potent antioxidant that scavenges free radicals and prevents them from contributing to oxidative damage. MCTs are a source of medium-chain fatty acids (MCFAs). MCFAs can be used by the heart for energy production. They do not require a carnitine transporter to get into the cardiomyocyte mitochondria and are easily oxidized to produce ATP. They can also be converted into ketones by the liver, which are used by the heart muscle as well. MCTs serve as an alternate energy source for cardiomyocytes, which enhances mitochondrial function and reduces risk for oxidative stress. Continued on page 6
Amino acids (lysine, methionine and taurine)
Omega-3 fatty acids (EPA and DHA)
Magnesium
Vitamin E
Medium-chain triglycerides (MCTs)
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