Chronic kidney disease (CKD), also known as chronic renal failure or chronic kidney failure, is a condition characterized by the gradual decline of kidney function in dogs. The kidneys play a vital role in filtering toxins from the blood, and when they fail, these toxins accumulate, leading to further health complications. While there is no cure for CKD, nutritional therapy, specifically a well-formulated renal diet, is a cornerstone of managing the disease and improving a dog's quality of life.
Understanding Chronic Kidney Disease in Dogs
Chronic kidney disease is an irreversible loss of all of the kidney's functions. Although commonly considered an illness of older dogs, it can occur in animals of all ages. Chronic renal failure is not reversible and may have been present in your pet for months to years before the time of diagnosis. The goals of nutritional management are to meet the patient's nutrient and energy requirements, as well as to alleviate the clinical signs and to slow the progression of the disease. Specific recommendations regarding dietary therapy will vary from patient to patient and need to be based on clinical and laboratory findings.
The Role of Diet in Managing Kidney Disease
Nutrition plays a big role in the management of dogs with kidney disease. Recent studies in dogs and cats have shown both a reduction in the complications associated with renal failure, and an increase in life expectancy by feeding diets designed to manage renal disease.
If your dog is experiencing kidney failure, feeding them the proper diet will be key to treating and managing their symptoms. Your veterinarian may recommend a therapeutic diet featuring phosphorus, sodium, restricted protein, and increased omega-3 fatty acids for dogs with kidney failure and kidney disease.
Key Components of a Renal Diet
Kidney diets for dogs are significantly different from regular dog foods. Kidney diets for dogs have to tick a lot of boxes. Several key modifications are typically made in renal diets to support kidney function and overall health:
Read also: Canine Kidney Diet: Ingredient Breakdown
Protein Restriction
Recommending a diet with moderate to severe protein restriction is one of the most common approaches to managing kidney failure. Restriction of dietary protein has been demonstrated to slow the rate of progression of renal damage in rats and people. However the effect of protein restriction on the progression of renal damage in dogs and cats remains controversial and no definitive study exists on this matter.
Reducing the amount of protein in a dog's diet remains controversial, however, there are two main goals behind this approach. The first is to help lower the amount of waste produced during protein metabolism and the second is to minimize the amount of protein entering the filtration system of the kidneys. What this means is that feeding a diet with reduced levels of protein may help to reduce the workload placed on your pup's kidneys, in turn possibly helping to preserve kidney function for longer.
Many of the clinical signs that you see in your animal such as vomiting, lethargy, anorexia, diarrhea, oral ulcerations and the foul ammonia odor to their breath can be partially or completely alleviated by reducing the protein concentration in your animal's diet. These clinical signs, that are often referred to as uremia, can be caused by an accumulation of the breakdown products of protein metabolism (sometimes referred to as nitrogenous waste products). This protein comes from both the protein in your animal's diet, as well as mobilization and degradation of their own body's protein stores. Consumption of protein in amounts greater than what your animal needs to maintain normal bodily functions can exacerbate these clinical signs. The consumption of diets containing reduced protein levels decrease the amount of nitrogenous waste delivered to the kidneys for excretion in the urine. This may help reduce the excessive drinking (polydipsia) and urination (polyuria) in your animal. A reduction in dietary protein may also help reduce the degree of anemia in some patients. Anemia enhances the weakness and reluctance to eat in animals with renal failure. Anemia can occur for several reasons with renal disease, but one factor that is believed to make it worse is excessive dietary protein. Nitrogenous waste products are believed to contribute to anemia by reducing the life span of red blood cells.
Protein quality is also important. There’s a close relationship between protein intake and blood phosphorus levels. Dogs with kidney disease gradually lose the ability to excrete phosphorus in their urine, so it backs up in the bloodstream. An important way to reduce phosphorus levels in the diets of dogs with kidney disease is to not overfeed protein and to ensure that proteins relatively low in phosphorus are included in the diet.
Phosphorus Restriction
Close attention must be paid to the mineral balance in patients with chronic renal disease. Phosphorus, calcium, sodium and potassium are of particular concern. The latter two are often referred to as electrolytes. All of these can be easily measured using blood tests and are part of a routine screen in patients with chronic renal disease.
Read also: Managing Canine Lymphoma with Diet
As your dog's kidneys begin to fail, the concentration of phosphorus in their blood becomes elevated. Elevated concentrations of phosphorus have been linked to a number of negative side effects such as vitamin D deficiency and reduced ability for your dog's body to metabolize calcium. In dogs with chronic kidney disease, normalizing blood phosphorus concentrations through their diet may help to slow the progression of the disease.
One of the first alterations in mineral status that occurs with renal disease is phosphorus retention by the kidneys and this is manifested as elevated phosphorus concentrations in the blood (referred to as hyperphosphatemia). This increase in body phosphorus concentration can lead to numerous deleterious consequences such as vitamin D deficiency, in addition to alterations in the actions of other hormones that regulate calcium metabolism and subsequent calcification of bodily tissues. In dogs, dietary phosphorus restriction has been shown to slow the progression of renal failure. One goal in the management of renal disease is to normalize blood phosphorus concentrations. By reducing hyperphosphatemia, these changes can be minimized or prevented. This can be achieved by reducing the amount of phosphorus contained in the diet or by reducing the intestinal absorption of dietary phosphorus. Dietary protein sources contain high levels of phosphorus. This is another reason that foods designed for the management and treatment of renal failure contain reduced amounts of dietary protein. Unfortunately as renal disease progresses, restriction of dietary protein alone is often not sufficient to control blood phosphorus levels. Further control of phosphorus can be achieved by the addition of intestinal phosphate binders. These binders help to reduce the absorption of phosphorus through the gastrointestinal tract.
It's important to note that the phosphorus level in dog foods is directly related to the amount of protein in the food. In order to reduce the phosphorus in your dog's diet it will be necessary to also restrict their protein intake. It is also important to know that normalizing your dog's blood phosphorus levels through diet alone is typically only successful if the kidney disease is diagnosed and treated early, medications will also be necessary for more progressed stages of the disease.
Sodium Restriction
Restriction of dietary sodium is a common feature in diets designed to help manage chronic renal disease. Reducing sodium in the diet of dogs with chronic kidney disease may also be beneficial. Reducing sodium can help to reduce the workload on your pup's kidneys, as well as to help your dog to maintain normal blood pressure. Sodium restriction is instituted to help control high blood pressure (hypertension) that is associated with the diseased kidney's inability to excrete sodium normally. Hypertension is also theorized to contribute to the progression of renal disease. It is important to note however, that severe sodium restriction is also not prudent. Severe restriction can result in volume depletion and dehydration, exacerbating clinical signs and the disease.
Beyond feeding a therapeutic diet, reducing your dog's sodium intake will also mean paying special attention to the treats you offer your dog. Jerky and cheese slices are typically very high in sodium and should be avoided.
Read also: Diet for Seizures in Dogs
Increased Omega-3 Fatty Acids
Omega-3 fatty acids have been shown to help slow the progression of chronic kidney disease in dogs by reducing the production of inflammatory compounds that create oxidative stress to the kidneys. Foods with higher levels of omega-3 often contain salmon and other fish which many dogs enjoy, or may be supplemented with fish oil, or flaxseed oil.
B Vitamins and Vitamin C Supplementation
Animals with renal failure have an increase in their urine volume, and therefore an enhanced excretion of water soluble vitamins (B Vitamins and Vitamin C). Loss of these vitamins may contribute to the anorexia associated with renal disease. Diets designed for the management of renal disease are supplemented with increased amounts of water soluble vitamins, and further vitamin supplementation is rarely necessary.
Increased Fat Content
In order to compensate for this protein reduction, the concentration of fat is usually increased. An increase in dietary fat can be beneficial in several ways. On a weight basis, fat has almost twice as many calories as protein or carbohydrates. This increases the energy density (number of calories per cup or can) of the diet and therefore allows an animal to consume less food to meet its energy needs. Fat also enhances the palatability of the diet and makes it more appealing to an animal that might be reluctant to eat. However, in some animals extra dietary fat can cause problems. Signs that your animal may not tolerate the higher fat concentrations in these diets may include a reluctance to eat or a reduction in food intake, lethargy, nausea, vomiting, diarrhea or abdominal pain. Should any of these signs occur, you should contact your veterinarian immediately.
Potassium Management
Potassium is another mineral that can either increase or decrease with chronic renal failure. The most common scenario is potassium depletion. Potassium depletion occurs with chronic renal disease due to a reduction in dietary potassium intake in animals that are not eating well, as well as an increase in loss through the urine. However, there is a population of animals that may have elevated potassium concentrations. Your veterinarian will monitor potassium concentrations in the blood and will adjust intake accordingly.
Water Content
Kidney diets should also contain a lot of water. Dogs with kidney disease struggle to maintain their hydration. Wet foods are almost always a better option for dogs with kidney disease than dry foods. Some dogs might need as much as five 12-ounce cans a day to meet their calorie needs. In many prescription diets, you have at least two choices in flavors, such as chicken or lamb. But you may not realize that the chicken dry and the chicken wet may taste just different enough that your dog accepts one of them.
Encouraging Your Dog to Eat a Renal Diet
Your pet needs to consume sufficient calories to supply essential nutrients, as well as to prevent the breakdown of their body's protein stores that will cause malnutrition and exacerbate the clinical signs of uremia. If you notice that you animal is not eating well, or has stopped eating entirely, contact your veterinarian immediately. Do not attempt to force-feed the reduced protein diet to your animal. This may result in the animal associating feeling ill with the consumption of the therapeutic diet (also known as a learned aversion). Once they feel better, they will not want to resume eating the diet. It can then be very difficult to get them to consume any diet designed to address their special needs.
One important characteristic of a kidney diet for dogs can be the hardest to achieve: It has to be delicious! To counteract this effect, kidney diets need to smell and taste great. After all, a kidney diet that isn’t eaten isn’t going to do a dog any good.
Your next obstacle is often your dog, who might look at the food, then you, sending a clear message that says, “I’m not eating this stuff.” These ingredients are not always tasty. But don’t give up right away. Years ago, choices were limited; but today, several manufacturers make acceptable prescription formulas, and most offer a money-back guarantee. If your veterinarian only carries one brand, and your dog turns up their nose, then return the food to the clinic or manufacturer and request a prescription from your veterinarian for another brand of that prescription diet. Plus, if for example, your diabetic dog is struggling with weight loss, there might be multiple prescription formulas that fit their needs. “Many prescription canned foods come in multiple textures, with both a smooth pate and a chunkier stew with bits of meat and vegetables in gravy,” says Kate Basedow '13, a licensed veterinary technician.
Here are some tips to encourage your dog to eat their renal diet:
- Enhance Aroma and Flavor: “To increase the natural aroma of the food and tempt your dog to eat, add some water and let it soak in. Canned food can also be warmed up in the microwave or mixed with some extra water for increased scent. Recommending an appropriate food topper to make the food more appealing.
- Make it a Game: “Working for their food increases its value,” says Basedow. “If you act like the prescription food is something special that your dog has to earn, they will be more interested and get into it. Start by asking them to sit or do an easy trick, then make a big deal of praising him and offer a single kibble as a reward. Do this a couple times, then start increasing the amount of kibbles each time. Puzzle toys are another option that some dogs love. Food that is hidden in a funky contraption must be tasty, right?
- Appetite Stimulants: In addition, your veterinarian may prescribe an appetite stimulant like capromorelin oral solution (Entyce) to trigger your dog’s appetite.
- Transition Slowly: Pay special attention to how you make the transition. Do not change your dog’s food while they are still nauseated or feeling bad. Once your dog has a good appetite, start making the switch very slowly. Give them lots of time to get used to the new flavors, textures, and ingredients.
- Don’t Give Up: Don’t give up if you initially have trouble switching your dog to a kidney diet. Call your veterinarian if your dog won’t eat the recommended food.
Prescription vs. Homemade Renal Diets
After a dog has been diagnosed with kidney disease and their condition is stabilized, veterinarians typically recommend switching over to a prescription kidney diet. Your veterinarian may have recommended a particular food based on the details of your dog’s case.
Most regular dog foods will probably contain phosphorus and protein levels that are too high for dogs with chronic kidney disease. That said, your veterinarian may be able to offer prescription therapeutic foods. Specially formulated prescription diets are designed to meet all your dog's dietary requirements while offering restricted sodium, phosphorus, and protein. Consult your vet about which is best for your dog.
One big benefit of homemade kidney diets, however, is taste. If your dog simply won’t eat anything else, a homemade kidney diet is worth considering. A study published in 2012 showed how hard it is to find nutritionally complete and balanced kidney diet recipes in books and online.
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