Chronic Renal Failure (CRF) is a serious condition resulting in gradual, irreversible deterioration of kidney function over a period of months or years. The kidney consists of tiny funnel-shaped tubes called nephrons, which filter out toxins and reabsorb the water and electrolytes that balance the body. When an individual nephron is damaged by any cause, (aging, poison, infection, etc.) it stops working permanently. Fortunately the kidney can still function with as few as twenty-five percent of its original nephrons, as other nephrons can grow larger to compensate. Kidney failure occurs when the total remaining functioning nephrons drop below 25%.
Kidney failure creates several body disfunctions. Toxins, specifically nitrogen breakdown products from the liver, which are normally secreted as waste, build up in the blood causing many of the signs associated with CRF. Other components in the blood, such as phosphorus, sodium or potassium may rise or fall abnormally. A function unique to the kidneys besides filtration, is the production of a hormone, erythropoetin, to stimulate bone marrow production of red blood cells. When kidney function decreases, production of this hormone decreases, resulting in less than optimal production of red blood cells (anemia).
CRF can only be accurately diagnosed with clinical laboratory tests. There are some signs and behaviors seen in cats that indicate the likelihood of chronic renal failure and, if these are observed, the cat should be tested as soon as possible.
CRF is diagnosed by a blood chemistry panel, which measures levels of critical blood components such as blood urea nitrogen (BUN), and creatinine. Cats with chronic renal failure will have extremely elevated levels of these chemicals. A CBC usually indicates a low red blood cell count. Analysis of the urine will test for protein, bacteria, and blood, as well as the concentration of the urine. A urine culture is almost always done to rule out bacterial infection as a complicating factor.
Only 25% of kidney capacity is needed for normal functioning. Therefore, no signs will be seen until approximately 75% of total kidney function is lost. It is important to begin treatment as soon as the first signs appear in order to prolong survival. The following is a list of the most common signs seen in cats with chronic renal failure:
Increased/excessive urination (polyuria)
Increased/excessive thirst (polydipsia)
Nausea and gagging
Grinding or cracking sound in jaw
Vomiting (both clear/foamy liquid and food)
Decreased or complete loss of appetite
Constipation or lack of bowel movements
Poor, dull or unkempt hair coat
Halitosis (bad breath) and sores/ulcers in the mouth and on the tongue
Eating litter or potting soil
Sudden onset blindness
Convulsion, low temperature, coma (end-stage)
Almost all of the symptoms listed above can also be indicative of other diseases, most commonly feline hyperthyroidism. In fact, hyperthyroidism may mask chronic renal failure, which points out the need for an accurate diagnosis with complete bloodwork and urinalysis.
At the time of first diagnosis most cats are significantly dehydrated, vomiting, and not eating. In these cats aggressive treatment with intravenous fluid therapy is necessary to get them through the crisis. Electrolyte imbalances will be treated, and in some cases blood transfusions are necessary to combat severe anemia. Treatment is not finished when the cat is released from the hospital. Moat cats will need significant medical therapy at home as well. Below is a list of common at home treatments.
1. Histamine blockers such as famotidine (Pepcid AC) are given daily to prevent gastric ulcers and reflux esophagitis.
2. Phosphate binders such as Gaviscon or Amphigel are often indicated to block excess absorption of phosphorus from the diet.
3. Potassium supplementation may be necessary if water excretion through urination is excessive or if the appetite is poor.
4. If your cat is anemic, vitamin supplements containing iron and B vitamins are given to provide the building blocks for red blood cell production. If the anemia is severe, at home injections of a synthetic hormone (Epogen) to increase red blood cell production in the bone marrow may be instituted.
5. If a urinary tract infection is present, antibiotics will be given for a period of at least 2 weeks, sometimes longer.
6. If your cat has high blood pressure, medications such as enalapril or amlodipine may be needed.
7. If your cat has a poor appetite or is completely anorexic, appetite stimulants such as cyproheptadine may be prescribed. When cats are sufficiently hydrated, appetite usually returns to normal.
Subcutaneous Fluids (SQ fluids)
Most cats will need additional fluid supplementation at home, and owners can be taught to administer fluids under the skin. This can be done several times a week or even daily if necessary. SQ fluids will help to keep your cat better hydrated, and therefore feeling better.
Your cat will probably be prescribed a low protein, low phosphorus diet to be used for the rest of it's life. There are several prescription diets available such as Purina NF, Hill's k/d, and Walthams low protein. Remember these diets are restricted in protein and should not be used for all cats in the household.
After diagnosis and initial treatment, your cat needs to be evaluated every 3-4 months with complete bloodwork and urinalysis including a urine culture. In some cases it may be necessary to evaluate your pet more frequently, especially if changes in appetite, thirst or urination are noted at home.
Unfortunately, chronic renal failure is a terminal disease. The only questions are how long and how well your cat will live until the end. With proper treatment, your cat may have from months to years of relatively high-quality life. As chronic renal failure progresses and toxin levels rise, cats become more uncomfortable with an overall sensation of feeling unwell. As time passes you will be faced with questions regarding your cat's quality of life. We will be there for you to help you make any difficult decisions that have to be made in order to do what is best for your cat.
If your cat is exhibiting signs related to chronic kidney disease please call 516-379-6200 to schedule an appointment for an examination and bloodwork today.