Diagnosis
Early detection of decreasing kidney function will allow treatment to begin while the cat has greater than 25% of function remaining. To intervene at this point, we must be looking for it. Beginning at 7 years of age, all cats should have baseline blood work, urinalysis, and blood pressure checked as a part of the annual physical exam. As the cat ages, these tests should be performed more frequently. Remember, most cats are not diagnosed until less than 25% of function remains and they are already in failure. The following sections describe common diagnostic tools used to evaluate your cat’s condition.
Superchem/CBC/T4 - This panel evaluates kidney and liver function, glucose, electrolytes, indirect blood pH, and thyroid function.
BUN (blood urea nitrogen) - Normal 8-35 - Urea is made from ammonia in the liver and is excreted from the body by the kidneys. As the kidneys fail, this value will rise.
CR (creatinine) - Normal .5-1.8 - Creatinine is a muscle by-product that is eliminated by the kidneys. This also elevates in renal failure.
Potassium - Normal 3.2-5.5 - This electrolyte has many functions in the body. The kidneys normally reabsorb it. As failure progresses, the body is depleted of potassium (hypokalemia) as it lost in the urine.
Phosphorous - Normal 2.5-6.5 - This mineral is normally excreted in the urine. In failure, it builds up in the bloodstream (hyperphosphatemia). Excess phosphorous has many negative effects on the body.
CO2 (carbon dioxide) - Normal 18-25 - This value is used to estimate blood pH In CRF, the blood usually becomes acidotic (too acidic).
T4 (thyroid hormone) - Normal .8-4.0 - Hyperthyroidism (increased thyroid hormone) is another common disease in the geriatric cat. Often it is found concurrently with CRF. If the level is very low, it aids in the prognosis.
CBC (Complete Blood Count) - This evaluates the red blood cells(rbc), white blood cells (wbc), and platelets.
PCV (Packed Cell Volume or hematocrit) - Normal - 27-42 - This is a measurement of the red blood cells. The kidneys normally produce a hormone, erythrpoeitin, which stimulates the bone marrow to produce red blood cells. As this hormone decreases, anemia develops. WBC (white blood cell count) - Normal - 6,000-18,000 - Total WBC count and the percentage of the different kinds of white cells provide information about the immune system. Platelets - these play an important role in clotting. Urinalysis - Many things can be learned from this test.
1. The specific gravity (S.G.) is a measurement of the concentration of the urine. As the kidneys deteriorate, they lose the ability to reabsorb fluid. This is the cause of the polyuria. Normal S.G. should be greater than 1.035 (the S.G. of water is 1.000). This is the perfect example of why baseline values should be obtained before the disease develops. EXAMPLE: A drop in a cat’s urine S.G. from 1.080 at 7 years of age to 1.040 at 12 years old demonstrates a significant decrease in the concentrating ability of the kidneys even though the later level is greater than 1.035. 2. There should only be a minimum amount of protein in the urine. If greatly increased, this is another indicator of poor renal integrity. 3. Most commercial cat foods produce an acidic urine. With CRF, the blood is already too acidic. Therefore acidifying diets should not be fed. This can be monitored by the pH of the urine. 4. Red and white blood cells in the urine may indicate infection in the urinary tract. Normally it is difficult for bacteria to live in the cat’s urinary tract because the urine is very concentrated and acidic. As the urine becomes dilute, bacterial infection is common. Approximately 25% of renal failure patients have active urinary tract infections, therefore, it is recommended to culture the urine prior to treatment. Blood Pressure Measurement Normal blood pressure should be less than 170mmHg. Cats suffer from the "white coat syndrome" (i.e nervousness falsely increases the blood pressure) just like their human owners making multiple readings necessary. If the values are consistently above 200 mmHg, treatment is indicated. RadiographsX-rays are recommended to evaluate the size and shape of the kidneys. Any calcification within the kidneys will also be evident. Treatment of Early Chronic Renal Failure If chronic renal failure is diagnosed while the cat still feels well, you are taught to give subcutaneous (under the skin) fluids at home 1 to 3 times a week. The frequency is determined by the clinical signs. B vitamins and potassium chloride may be added to the fluids. If you are unable to do this at home, arrangements can be made to have it done on an outpatient basis. Blood pressure medicine will be prescribed if needed, and antibiotics are often given. See the section on medications and diets for further information. Treatment for Decompensated Chronic Renal Failure The treatment goal for chronic renal failure in the cat is to detect any underlying causes, treat any immediate problems, get him eating so he can be managed at home, and to slow the progression of the disease. Initially these cats usually present with signs of weight loss, anorexia, lethargy, and severe dehydration. The cat must be placed on intravenous fluids to correct the dehydration. Different medications and fluid additives are also needed to correct the electrolyte and metabolic abnormalities. He may go home at night or stay in the hospital, but we do not provide around the clock care. Severely debilitated cats may require overnight monitoring and treatment at an emergency clinic. The IV fluids are usually continued for 3 to 5 days when blood values are reevaluated and a home care plan developed. Subcutaneous fluids will be needed for the rest of the cat’s life. Refer to the sections on medications and diet for further information. Medications Used in CRF 1. Subcutaneous (SQ) fluids - Fluid therapy is the mainstay of the management of chronic renal failure. The fluids help maintain adequate hydration and will help flush out toxins. Lactated Ringers Solution (LRS) is usually the fluid of choice. Potassium chloride, B vitamins, and/or sodium bicarbonate may be added as needed for additional supplementation. The volume and frequency of fluid administration is determined for each individual. The fluid assembly consists of the bag, the set-up, and needles. Each bag of fluids contains 1000 mls and normally 100 to 200 mls are given at a time yielding 5 to 10 treatments per bag. The set-up connects to the bag of fluids and may be reused several times. To keep the set-up sterile, it must be taken from the old bag and inserted immediately into the new one. Do not lay it down. The fluids flow into the cat by gravity (i.e., the higher the bag is above the cat, the faster they will run). This can be accomplished by hanging the bag on a door knob while you sit with the cat on the floor. Many people will find the cat easier to manage on a counter or a table. You can hang the bag on top of a cabinet door, a coat rack, etc. Eighteen gauge (green) needles are ideal because they allow the fluids to flow quickly. A few cats prefer twenty gauge (pink) needles because they are smaller, however the fluids flow much slower. To attach the needle, the clear end is twisted and removed to expose the hub which is connected to the set-up. Carefully remove the green needle cover and insert the needle into the skin as instructed by the doctor. After finishing, remove the needle and carefully replace the needle cover. Immediately replace the needle with a new one to keep the set-up and fluids sterile. This new needle is used the next time you administer fluids. Discard the used needles in a container such as a plastic milk bottle and return to us for proper disposal. Hazardous wastes must be incinerated by a licensed and certified company so there is a small fee for this service. When you need a refill, you will be asked if you need a new set-up and how many needles are required. Please call ahead so you do not have to wait for us to prepare the fluids. Note: Protect the fluids from sunlight and extremes of temperature. 2. B vitamins - B vitamins are water soluble and are lost in the urine. Polyuric cats need replacement of these vitamins. They are usually added to the fluids, and the specially formulated kidney diets are fortified with B vitamins. Also, oral B vitamin and iron supplements are available. 3. Potassium Chloride - This form of potassium is added to the fluids if needed. Most of the cats will need potassium supplementation. Depending on the frequency of fluid administration, oral potassium may be needed.
4. Potassium gluconate - The oral form of potassium supplementation.
A. Tumil K is a powder form that may be sprinkled on the food. 1/4 tsp twice a day is the initial dosage. Tumil K also comes in a chewable tablet and a flavored gel, each with respective dosage recommendations.
B. Generic potassium gluconate (found in the vitamin section of the pharmacy) may also be used. The dosage is ½ of a 550mg tablet twice a day. Check the ingredient list to make sure there is not any phosphorous added.
5. Cyproheptadine (Periactin) is used as an appetite stimulant. It may take 48 hours to see a response. However, many cats will want to eat within 20 minutes. The dosage is 1/4 to ½ tablet twice a day.
6. Pepcid AC is an over-the-counter histamine blocker to decrease stomach acid production. Gastrointestinal ulceration and bleeding are common when the BUN (blood urea nitrogen) is elevated. The dosage is ½ tablet once a day.
7. Phosphate binders decrease phosphorus absorption from the intestine. Ideally phosphorus should be kept at less than 6.
A. Amphogel tablets - dosage is 1/4 tablet 2 to 3 times a day with a meal or within 2 hours of eating.
B. Phos-Ex (calcium acetate) - dosage is 75 mg 2 to 3 times a day for a 5 pound cat or 150 mg 2 to 3 times a day for a 10 pound cat with a meal or within 2 hours of eating.
8. Norvasc - This is the first drug chosen to treat most hypertensive cats. The dose is 0.625 mg once a day. You need to watch carefully for signs of weakness. Weekly evaluations are needed until the blood pressure is stabilized. Thereafter, it is monitored every 2-3 months.
9. Antibiotics are often needed for 3 to 6 months if a kidney infection is suspected.
10. Winstrol is an anabolic steroid used to stimulate red blood cell production in mild to moderate anemia. The dosage is 1 mg daily. The injectable form may be given once or twice a week if needed.
11. Epogen is human erythropoietin. This hormone is produced by the kidneys and stimulates the bone marrow to produce red blood cells. The drawback to this drug is that 25 to 30% of cats will make antibodies against it within 30 to 90 days. These antibodies will also attack any feline erythropoietin still being made by the kidneys. In these cases, the cat may need transfusions until the antibody level decreases. Therefore, it is reserved for cats with severe anemia. To try to avoid the antibody formation, it can be used until the anemia is resolved and the cat can be switched to Winstrol. An injection of iron must be given, and the blood pressure should be normal prior to starting this regimen. For unknown reasons, most cats feel better within several days even though the red blood cell count has not risen yet. The dosage is 45 to 65 units per pound injected subcutaneously (under the skin) 3 times a week. As the red blood cell count increases, the frequency of injection decreases.
Diet
If decreased renal function is diagnosed early, it is recommended that a diet with decreased phosphorous and sodium be fed. Excess phosphorous causes an increase in parathyroid hormone which is a known renal toxin. Decreasing sodium in the diet is also important in preventing and managing hypertension which will hasten renal failure.
Once chronic renal failure is diagnosed, a lower protein diet is indicated. BUN is the end result of protein metabolism. By decreasing protein intake, the BUN is decreased and clinical signs improve. These diets are also restricted in phosphorous and sodium. A low protein diet is great in theory, but as the protein content of the food decreases, so do the chances that the cat will eat it. The typical cat in CRF usually has some degree of anorexia. At best, his appetite is picky. The most important aspect of the diet is to insure adequate calorie intake (a geriatric cat should consume 35 to 40 kcal/lb/day). Initially, he should be fed anything he will eat, then gradually introduced to the new diet. Some cats will develop an aversion to a new diet if it is offered in the hospital or when he is sick. Therefore, Cyproheptadine may be needed to stimulate the appetite. Recommended foods include Hill’s Prescription Diet k/d, Select Care Modified , or CNM-NF. The enclosed homemade diet can also be offered. Fresh water should be available at all times. Many cats will drink distilled water better than tap water. Constipation is common in these cats due to chronic dehydration. Metamucil or canned pumpkin may be added to the diet to alleviate this problem.
Many cats with chronic renal failure can lead a happy and comfortable life for many months to several years. The earlier in the course of the disease the diagnosis is made, the longer the life expectancy. Your dedication will be rewarded by providing the maximum quality and quantity of life to your feline companion. Please contact a member of our staff with questions or concerns at 703- 922-8228 (9 CATCAT).
Homemade Diet for Cats with Chronic Renal Failure
(Diet is courtesy of Hill's )
1/4 lb. Liver (beef, chicken, or pork)
2 Large eggs, hard-cooked
2 Cups cooked white rice without salt
1 Tbs. vegetable oil
1 tsp (5g) calcium carbonate
1/8 tsp potassium chloride
Also add a balanced supplement which fulfills the feline MDR for all vitamins and trace minerals, and 250 mg taurine/day.
Dice and cook meat in a skillet, retaining fat. Combine all ingredients and mix well. This mixture is somewhat dry and the palatability may be improved by adding some water (not milk). Yields about 1 1/4 lb.
Feeding Guide
Feed sufficient amount to maintain normal body weight.
Body weight Approximate daily feeding
5 lb...............................................1/4 lb.
7-8 lb...............................................1/3 lb.
10 lb...............................................2/3 lb.
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