Chronic kidney failure is a common problem in older animals but can also be seen in younger animals with congenital abnormalities. The kidneys are responsible for many things including removing naturally occurring waste products from the body. Creatinine and blood urea nitrogen (BUN) are two of these waste products that are easy to measure through blood testing and are representative of kidney function. When the kidneys fail, these waste products build up in the blood and cause the animal to feel ill.

A low protein/low phosphorus diet is one of the mainstays of treatment of chronic renal failure. The protein in the diet is broken down by the body to be used for energy and one of the by-products is blood urea nitrogen (BUN). As BUN level rises, the animal starts to feel worse. By feeding a low protein diet there is less BUN that needs to be removed by the kidneys and sometimes a diet change alone will make a significant difference in how animals feel. There are a number of low protein/low phosphorus prescription diets available: Royal Canin Modified Formula, Purina CNM N/F & Hill's K/D are among them. The nutritional aspect of management is important and contributes to how well or poorly animals may feel but there was no proof (in the past) that it actually alters the progress of the disease but recent studies indicate that survival is, indeed, increased if animals with CRF are willing (some are not) to eat a diet designed for the condition.

For those animals who will not eat any of the diets available, please remember that they MUST eat! It is better to feed a less than ideal food and make other adjustments (where possible) to attempt to balance it out rather than to under-feed or feed under stress.

Subcutaneous fluids (fluids administered under the skin) help flush out toxins and can help prevent dehydration. The dose and frequency of administration varies based on how well the kidneys are functioning and how the animal feels. It may vary from twice a week to twice a day.

Because the kidney is responsible for getting rid of excess phosphorus that is in the food we/they eat, phosphorus levels climb with kidney failure. High phosphorus levels can reduce appetite and also bind to calcium in the blood stream and cause mineral deposits in the kidney and other places in the body. There are two main strategies for keeping phosphorus levels low: don't feed much and prevent absorption of what you do feed.

Kidney diets are low in phosphorus but additional removal of phosphorus may be required for some animals. This is accomplished with the use of medications given with meals known as phosphate binders. These medications bind the phosphorus in the food and prevent it from being absorbed into the bloodstream. They used to be easily available over the counter under the names Amphogel or Basalgel (brand names of Aluminum Hydroxide (AlOH) but seem to have disappeared from the shelves in recent times. They are, however, easily available in a much more animal friendly form from a good veterinary compounding pharmacy.

These pharmacies can compound/flavour this and most other drugs into Medicated Chews/Treats, Flavored Liquid, Capsules & Trans-Dermal Gels (apply to ears). The chews and flavored liquids are an exciting and innovative delivery system but the role of the capsules are not to be underestimated. Many drugs come in tablet(s) only, dissolve quickly in the mouth and leave a very bitter taste. Crushed and put into food, they adulterate the food as well and both the meal and the medication are refused. This is particularly true for cats. Dogs are more likely to take medications wrapped in cheese or liverwurst and do so without any difficulty. Cats do not lend their discerning tastes to this method and need to be "pilled". Unless one is swift and experienced at doing so, this can be challenging and cause great distress to cats as the bitter medication begins to quickly dissolve and coats their mouths producing salivation and even vomiting. Veterinary Compounding pharmacies will compound the drugs required and supply them in the smallest size capsule the exact dose requires (remember, many tablets have to be split into two or four sections in order to achieve the dose required if done at home with the uncompounded tablet). They still have to be "pilled" but if it doesn't go perfectly well, there is no danger of the medication dissolving and coating the mouth. This capsulation or re-capsulation also allows for very precise dosing and change of dosing as the weight and condition of the animal changes.

Anemia (low red blood cell count) is a frequent occurrence in animals with chronic kidney failure. The kidney makes a hormone called erythropoietin that tells the bone marrow to make new red blood cells to replace older cells as the older cells are removed. When the kidney fails, it stops making adequate amounts of this hormone. The anemia that develops tends to occur slowly, allowing the animal time to adapt. When the anemia is moderate to severe, these animals will always be tired and won't want to eat very well. Blood transfusions can help for a short while but transfused cells do not last very long and the transfusions would need to be repeated every few weeks. There is a human form of the hormone called Epogen that can be given to stimulate new red blood cell production. It is given by injection under the skin (similar to insulin) with a very small needle. The typical dosing schedule is three times weekly until the measure of the red blood cell count (PCV or Hematocrit) is normal. It is then reduced to twice a week until stable and then once a week for maintenance thereafter. The PCV level must be checked weekly to begin with but when the target has been reached, it can be reduced to a less frequent (perhaps every one to three months) interval.

This drug must be kept in the refrigerator. Because it is available only in human form, some (one out of every four) animals' bodies will recognize it as foreign and make antibodies that bind to it rendering it inactive. When this happens, the anemia becomes worse. Treatment for this is to discontinue the hormone and wait for the antibodies to disappear. This can take several months and in some cases, up to a year. This, unfortunately, means that repeated blood transfusions become necessary which increases the risk of transfusion reaction. For this reason, treatment with Epogen is not casually recommended and reserved for anemia that is moderate to severe.

Because iron is an essential part of new red blood cell production, iron supplements are often given to animals receiving Epogen therapy. Oral iron supplementation can be very upsetting to the stomach but in can be given by injection to cats. Iron supplementation alone (absent of Epogen therapy) will not increase red blood cell production.

Gastric ulcers are a common problem in animals with kidney failure. This is the result of the toxin build-up. These ulcers cause discomfort/pain, nausea and vomiting (occasionally with blood) as well as reduced appetite. Acid reducing medication like Pepcid AC and Tagamet are helpful in this case and Pepcid AC is also available in an injectable form, which is easily administered under the skin with a very small needle. Some animals require a medication to coat and soothe the irritated stomach lining insulted by ulcers or severely inflamed pre-ulcerative states. This drug (sucralfate ~ brand name, Carafate) can be given along with the others but not at the same time as it prevents the absorption of other drugs while in the active period of coating/protecting the stomach. They should be given an hour or more before or after any other drug. Your veterinarian will help to guide you through this process and personalize the administration of any and all the therapies needed to maximize the comfort and well-being of your cat or dog.

Oral ulcers and stomatitis (an inflammation of the mucous lining of any structure of the mouth) can also present themselves and must be addressed. Often, animals with CRF will experience decreased appetite or complete refusal to eat. It is a common symptom in the process but should not be presumed to be caused only by the usual complications of nausea or GI difficulties. A careful oral exam must be included to rule out the presence of stomatitis (with or without ulcers) as the cause. The discomfort and pain associated with stomatitis may be the reason for reluctance or refusal to eat. Examination of the mouth can be challenging and a consultation with a Board Certified Veterinary Dentist is a beneficial addition to the care plan.

High blood pressure (hypertension) is another commonly occurring part of the CRF landscape and occurs about 20% of the time. In specialty practices (which is where I recommend CRF be treated) the incidence of hypertension has been reported to be as high as 65%. This is likely due to the ability of the specialist to make this determination with the sophisticated equipment and experience in using it (the equipment) that is available. The presence of hypertension must be determined or ruled out by an initial (baseline) reading and followed (even if normal) with routine monitoring. This is done in the clinic/hospital setting which can be stressful and produce what, you may be concerned, is a false reading. "False" readings (due to stress) are not a secret to your Board Certified Internist or Nephrologist who will arrange for multiple readings (each time) in the best possible situation(s). This will allow for a reliable trend with which to make the diagnosis.

If present, it must be treated with antihypertensive medication. Hypertensive cats (and many dogs) will require life-long treatment with this medication. The most frequently and successfully used drug is Amlodipine (brand name is Norvasc). If left untreated or uncontrolled, hypertension can and will cause damage to the brain, eyes and heart.

Chronic kidney failure is not to be confused with acute kidney failure, which can be fatal within a short time like in the case of poisoning with agents that shut down the kidneys. Chronic kidney failure can be managed and most animals compensate and can do well for long periods of time.

This article is Copyright © Barbara Meyers,
and printed with permission of the author.

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