An important trend in nutrition research is aimed at preventing disease, not just treating it.
Susan H. Bertram, DVM
While dog food manufacturers don't yet offer such futuristic formulations, "it's not outside the realm of possibility," said Timothy Bowers, DVM, who is completing a Ph.D. in veterinary nutrition at the University of California, Davis. "An important trend in nutrition research is aimed at preventing disease, not just treating it, but we're very early in the learning curve."
Fortunately, nutritional therapy - using nutrition as part of a treatment for a specific disease - already helps treat many chronic diseases and can prevent some common health problems.
Therapeutic diets offer specialized nutrition for a medical problem - adding or reducing nutrients that are known to influence certain organ systems or metabolic pathways - to lessen symptoms and simply make the pet feel better.
The first commercially available medical diet, formulated by Hill's Pet Nutrition of Topeka, Kan., for dogs with kidney failure, appeared 50 years ago. Since then, many pet food manufacturers have developed dozens of therapeutic diets. Special diets for dogs address heart failure, food allergies, diabetes and bladder stones, to name a few.
The decision to research a certain type of diet evolves from scientific considerations and consumers' suggestions. "We pay careful attention to what is going on in scientific arenas, even in human medicine, and ask the question 'Why are we seeing this?' and 'Is it something that diet might influence?'" said Dan Carey, DVM, director of technical communications for The lams Co. in Dayton, Ohio. In addition, consumers are becoming more knowledgeable about nutrition for their pets, said Steven Hannah. Ph.D., nutrition scientist at Ralston Purina Co. in St Louis. "They are demanding better products and technical explanations for what they're feeding."
Many manufacturers maintain research facilities, where they study nutrition in healthy dogs. Clinical trials, where diets are tested in ill patients, are conducted in cooperation with veterinary colleges and veterinarians in private practice "Nutritionists, engineers, food scientists and veterinarian are all part of the research-and-development team," said Mike Hand, DVM, a bo ard-certified veterinary nutritionist and vice president of research for Hill's.
Among the more innovative projects, the Morris Anima Foundation funds research at Colorado State University that studies how nutrition may help treat cancer. Dogs with cancer have an abnormal metabolism of proteins, carbohydrates and fats, which serves to enhance tumor growth while starving the patient of energy regardless of the amount the dog eats. Preliminary studies have demonstrated a diet with complex carbohydrates (instead of simple sugars), highly bioavailable proteins that can be easily digested and used by the animal's body, and moderate levels of fats (including omega-3 fatty acids) can help animals with cancer gain weight and respond better to chemotherapy, radiation or surgical therapy.
In some cases, the diet may slow tumor growth. Researchers emphasize no definitive "cancer diet" has been determined, so homemade recipes or commercial versions aren't currently available but are an ultimate goal.
Recent research has dispelled many dietary myths and led to the development of innovative specialty diets addressing large-breed puppies, geriatric and obese dogs, and those with diabetes, food allergies and kidney failure. Large-breed puppies used to be given calcium supplements for their big, rapidly growing bones. Current findings prove they need less calcium than smaller breed puppies.
Lower-calcium diets may stave off developmental bone diseases called HOD (hypertrophic osteodystrophy) and osteochondrosis. Pushing calories for rapid growth is equally harmful. "The adult size of a dog is genetically determined," Dr. Carey said, "and if large-breed puppies, those that will weigh 65 pounds or more as adults, are fed to grow more gradually, they have fewer problems with their bones but will still attain their full adult size." Several large-breed puppy foods incorporate these discoveries.
On the other end of the age spectrum, geriatric dogs were once thought to need less protein in their diet for maintaining muscle because they are more sedentary. In fact, the opposite is true: As long as they don't have preexisting kidney disease, older dogs actually need more protein, Dr. Hannah said. With this in mind, Ralston Purina developed two diets for older dogs that contain different fat levels, recognizing some older dogs are too thin and some are overweight.
Although obesity is the leading nutrition-related disease in dogs, many premium diets contain high fat levels, which improve palatability. Some manufacturers, such as Waltham USA Inc. in Vernon, Calif., offer diets that address various medical conditions - such as kidney and liver disease, gastrointestinal disease and food allergies - but also offer lower fat levels. "[They] rely on high-quality proteins and grains for palatability," said James Sokolowski, DVM, Ph.D., professional services manager for Waltham.
Dose of Insulin
Waltham also offers a diet formulated to manage diabetes mellitus. It contains 7.5 percent fat, and its blend of soluble and insoluble fiber has been clinically proven to help regulate blood glucose levels and may allow a lower dose of insulin, Dr. Sokolowski said.
Food allergies, which can cause itchy skin and dermatitis in dogs, may also cause some forms of inflammatory bowel disease, a syndrome of vomiting, diarrhea and weight loss. Managing these conditions requires finding a diet the dog can - and will - eat and that will not cause an allergic reaction. Ralston Purina Co. offers a diet that contains a modified protein which, because of the small size of the protein molecule, a dog's system will not recognize as an allergen. "It is a true hypoallergenic diet," Hannah said.
Renal-failure diets typically rely on restricted protein levels to reduce the buildup of urea in the blood, which must be cleared by the kidneys. But restricted protein can worsen muscle wasting and weakness in renal- failure patients, because renal failure is a protein-losing disease. The animal begins to break down its own muscle mass. To prevent those problems, The Iams Co. last year introduced a renal-failure diet that delivers higher levels of proteins for better nutritional support but uses fermentable dietary fibers to enhance blood flow and bacterial activity in the large intestine. Bacteria can actually trap urea in the colon, reducing how much must be cleared by the kidneys Dr. Carey said.
Periodontal disease also can be addressed through diet. One manufacturer offers diets made to reduce plaque and gingivitis. "It's a good example of a product matching a need," said Debra Nichols, Ph.D., vice president of product development for Hill's, "because periodontal disease is such a common health problem in dogs, and dog owners are more aware and concerned about dental disease in their pets."
Commercial diets aren't the only option for a dog with special dietary needs. At the University of California, Davis, the veterinary nutrition service uses a computer program to develop and analyze homemade therapeutic diets for dogs. The service is available to veterinarians, who can contact the school and provide the medical details needed to develop the appropriate diet. There are pros and cons compared to commercial formulations, Dr. Bowers said. "With a homemade diet, you can use ingredients that aren't available commercially and can customize the diet to the patient. For example, if a dog has pancreatitis and kidney disease, it needs a low-fat diet plus restricted protein and phosphorus." The disadvantage of a homemade diet is the difficulty in determining if it is complete and balanced, because controlled feeding trials aren't done. In addition, he said, "A big problem occurs when people change ingredients, such as substituting chicken for beef in a recipe. It totally changes the diet."
Dog owners need to work with their veterinarians to determine which, if any, therapeutic diets are appropriate for their dogs. "Few medical conditions are solely responsive to diet," Dr. Bowers said, "but nutritional therapy is an important complement to other medical treatment. We try to integrate the two."
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