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What is Chronic Kidney Disease?
Please understand the following information is offered as a courtesy and is not intended to provide a diagnosis or medical recommendation for your pet.
Introduction
Your animal has kidney disease, which means that toxins are backing up in the blood because the kidney can no longer remove them. This occurs when more than 75% of the kidneys become non-functional. The exact cause of this loss of function often remains unknown. We have made every effort to identify reversible causes, such as infection or stone disease, but they are not present. Unfortunately, after this amount of kidney loss, there is sometimes further decline in kidney function (self-perpetuating progression of the original disease). We may be able to slow this decline.
Major Goals of Treatment
Many of the toxins building up in the blood are chemicals derived from the diet. Nutrients in the diet that may contribute to progression of the disease include protein, phosphorus and sodium. By limiting the intake of these nutrients, while still providing an excellent quality diet, we can maintain your pet's nutritional status and reduce generation of toxic products. It also is important to provide enough calories to prevent the body from breaking down its own tissues as a source of calories (which adds further to the toxic products). By reducing the amount of waste products, animals often feel better, so they become more inclined to eat and to be more active. Progression of the kidney disease also may be slowed by proper diet therapy.
Primary Treatment:
- Special Diets - Special diets for patients with chronic kidney disease are designed to limit the intake of protein, phosphorus and sodium, while avoiding deficiency of any of these essential nutrients. Signs of nutrient deficiency in animals fed these special diets include muscle loss, poor haircoat and listlessness. These signs are not specific, however, and may be associated with other problems. If you see any of these develop in your pet, contact your veterinarian to have them evaluated.
You can feed your pet a commercially-available diet, such as k/d®, or cook a home-made diet (recipe follows this information). These special diets may be uninteresting to dogs and cats. Their appeal can be increased by warming the food (to body temperature) in a microwave before feeding, or frying in the skillet ("burgers").
- Water - The second major thrust of treatment for chronic kidney disease is to make sure that your pet receives enough water and other fluids. Animals that do not receive enough fluids may become dehydrated, which decreases the amount of blood flowing to the kidney to permit waste products to be flushed out of the system. Signs of dehydration to watch for include a dry, "tacky" mouth and loss of skin pliability, which causes the skin to stick together when pulled away from the body.
Access to fresh water at all times is important. Do Not Restrict Water for Any Reason, unless your veterinarian specifically requests you to do so. Some animals drink more water when water bowls are refilled frequently, and water may be added to the animal's food if it is eating well. At certain times, it may become necessary to administer water from a feeding syringe (the exact volume will be prescribed if this becomes necessary).
Extended Treatment
- Phosphorus Binders - Phosphorus binders are designed to prevent phosphorus absorption from the intestinal tract. They bind more phosphorus when given with meals. This will result in less phosphorus in your animal's blood, which is beneficial. In addition, it can act as a coating agent for small ulcers which occur commonly from uremic poisoning. It also may help to prevent progressive kidney damage. Aluminum hydroxide (Amphojel ®), calcium carbonate ((Oscal-500® without additional vitamin D, or TUMS®) and calcium acetate (Phos-Ex®) are the compounds we use most commonly.
- Potassium supplementation - Sometimes additional potassium can be helpful, especially when your pet's blood potassium blood measurement is low. If your veterinarian recommends it, potassium chloride can be added to the bag of fluids before giving it subcutaneously. For cats, potassium gluconate (Tumil-K®) may be sprinkled on food if recommended.
- Stomach Acid Control - There is a tendency among animals with kidney disease for increased acid secretion by the stomach, which may cause ulcers in the stomach and intestine. Cimetidine (Tagamet®) ranitidine (Zantac®) or famotidine (Pepcid®) are antihistamines specially designed to decrease the secretion of gastric acid. The appetite of some animals with uremic poisoning benefits from use of these drugs. This medication may need to be continued indefinitely, but usually we try to taper your animal off of this medicine if possible.
- Calcitriol Supplementation - Parathyroid hormone (from a gland in the neck that controls blood calcium levels) is usually increased in animals with chronic renal failure. Too much parathyroid hormone is toxic to many tissues and may contribute to kidney disease. Some of this excess can initially be controlled by limiting the amount of phosphorus entering the animal's body through diet and phosphate binders. Dietary control and phosphorus binders may not be enough in many cases, however. In these instances, calcitriol (vitamin D made in the healthy kidney, but missing from diseased kidneys) can be helpful. This vitamin can directly suppress parathyroid hormone production. One possible side-effect of calcitriol is that too much calcium may enter the body. Consequently, it is necessary to measure blood calcium periodically to make sure that it is not becoming too high.
- Fluids Injected Underneath the Skin - During times when your pet doesn't eat enough or take in enough water it may be helpful to give fluids under the skin (subcutaneously) with a needle and drip line from a bag of fluids. This is initially done by your veterinarian, but most owners can easily learn to do it at home. Initially, fluids may need to be given twice daily, but we try to limit the amount and number of times to what is absolutely needed. Often the fluids are only given intermittently, once or twice weekly to help "pick them up" when needed.
Less Common Treatments
- Combating anemia - Renal failure often is associated with anemia due to the lack of a signal from the kidney to the bone marrow to make new red cells. Anabolic steroids such as decadurabolin® at times can be helpful in uremic poisoning, particularly in their effects at stimulating the bone marrow to produce new red blood cells. Unfortunately, this effect is weak and may take 4-6 weeks before it is seen. It also has effects in promoting mineralization of the skeleton and in stimulation of appetite.
- Control of Acid Build Up in the Body - If acid accumulation secondary to kidney failure is severe, drugs to counteract this may be helpful. Usually sodium bicarbonate is added to the food, or provided as pills. Potassium citrate (Urocit-K®;Polycitra®) can be used when both acid and low potassium are a problem, or in situations where the sodium in sodium bicarbonate is not desired (as in high blood pressure).
- Erythropoietin (EPO®) - This compound is a product of recombinant gene technology in which synthetic human erythropoietin is manufactured. This hormone is made by healthy kidneys and is deficient in those with failing kidney functions. Erythropoietin treatment benefits those with severe anemia, especially those that require periodic blood transfusions. Some "allergic" problems develop in approximately 30% of dogs and cats receiving human erythropoietin, since human erythropoietin is not exactly the same as that in dogs or cats. These patients initially respond to this drug, but the effect is only transient due to antibodies directed against the drug. Erythropoietin is very expensive, but may be affordable for cats and small dogs. New erythropoietin products are being actively developed to correct anemia specifically in dogs and cats.
- High Blood Pressure - High blood pressure occurs frequently in dogs and cats with certain types of kidney disease. High blood pressure may cause several complications and we will recommend treatment as necessary.
Follow-ups (Measures of Success)
Increasing appetite, weight, and activity all are good signs that the medications and dietary management may be helping your pet. The only way to determine if the kidney disease is stabilizing is to measure the serum creatinine value periodically. If the creatinine remains relatively stable and less than 5.0 the outlook on treatment is better than with higher values. The BUN, although traditionally used to measure kidney function, is not useful for this purpose after diet change. It still is useful to evaluate the effects of the dietary protein restriction, however. Serum phosphorus measurement will allow us to determine the effectiveness of the phosphorus binding agents.
Additional test results on your pet's blood panel can be helpful to determine the degree of success in maintaining nutritional health (total protein, albumin, cholesterol). Information is also available from this panel that can give us estimates of how much acid retention (if any) is occurring in your pet. Urine is usually collected periodically and sometimes cultured to make sure that urinary infections do not become a problem (animals with diseased kidneys may be at greater risk to develop urinary infections which could put their kidneys at further risk for deterioration).
Prognosis
No single test can tell us how long your pet will live with chronic renal failure. Some animals tolerate renal failure (uremic poisoning) amazingly well, while others with the same degree of kidney failure are very sick. Information from the physical examination, response to treatments, general history of well-being, and laboratory data will provide us the needed information to provide the best care of your pet with renal failure.
Restricted Protein Diet for Dogs and Cats
1.5 cups (6 servings*) cooked meat (such as beef, chicken, pork, large egg)
4 cups (8 servings) cooked starch (such as rice, pasta, potato)
1 teaspoon vegetable oil
2 500mg Tums® tablets
1 complete vitamin-mineral supplement for a 2-3 year child
For cats, add 1 500mg tablet taurine
*Approximate Analysis of above ingredients:
Calories 1200 kcal** based on 1200 kcal)
Protein 60 gm (62)
Calcium 600 mg (2000)
Phosphorus 400 mg (1700)
Sodium 140 mg (200)
Potassium 500 mg (2000)
* Servings refers to items in the attached food lists, from which a much greater variety of foods may be chosen. In addition, up to two servings (total) from any of the fruit, vegetable, bread, desserts, fats and calorie supplements lists may be provided to enhance palatability and intake of the diet.
** (distributed as 20% Protein, 40% each carbohydrate and fat)
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