Chronic Kidney Failure

By: Dr. Warren Riggle

This article is in memory of Kasey, our 18 ½ year-old cat who died on November 29, 2011. My son, Ben brought Kasey home to us when he was in 7th grade. Kasey was a little white kitten who was a very active, inquisitive, spirited cat throughout her entire life. Kasey “demanded” attention, loved “Kasey rubs”, and enjoyed sitting on your lap. Kasey was commonly found jumping onto countertops, computers, tables, and anywhere she was not supposed to be. She continued to be a very active and vocal until shortly before her death. We really miss Kasey, and treasure all of our memories of our special cat. 

Chronic kidney (renal) failure is a common problem for cats and dogs, especially as they are getting older. It is possible, however, to have problems with the kidneys at any age. My own dog, Autumn, was born with a congenital kidney problem. (See previous blog article on our website: “Wellness Tests”). The kidneys are made of thousands of tiny filtration units called nephrons. The nephrons remove waste products from the blood stream from food that has been eaten.  The foods that we and animals eat have many, many waste products resulting from metabolism and that the kidneys filter from the blood stream. In addition, the kidneys retain and regulate essential nutrients, such as potassium, maintain hydration, stimulate red blood cell production, help regulate blood pressure, activate Vitamin D, and produce urine. It is common to refer to kidneys as failing when waste products are not eliminated in the urine adequately and their levels elevate in the bloodstream. Excess waste products, nature’s natural toxins in the bloodstream, cause pets not to feel as well. Pets become less active and eat less.  Kidney function will meet the body’s needs until at least 2/3 of the original nephrons are no longer working, assuming a dog or cat is born with a normal number of functioning nephrons. Another way to express this is, when the kidney tests show even slight elevation into the abnormal range, shockingly, at least 2/3 of the kidney tissue in the body is not working.  Autumn was not born with a normal number of nephrons and therefore, had less nephrons that she could afford to lose. This is one of the many reasons it is helpful to get a baseline on blood chemistry tests around 3-6 months of age and to consider additional tests at least yearly. 

There is a much better chance that renal failure can be treated successfully and that you can look forward to months and often years of quality life, if it is discovered early in the progression of the kidney decline, even before the tests are abnormal. We often detect trends long before the tests are abnormal and slow or cure the deterioration. Symptoms often associated with kidney disease include increased thirst, nausea, pain, weakness, appetite loss, intestinal bleeding, and even seizures.  To have the best chance to help kidney failure, it is best to discover the deterioration of the kidneys early. Unfortunately if you wait for signs from your pet, the kidney failure is typically quite advanced and more likely to be permanent. 

Tests that can help your veterinarian screen for your pet’s kidney function include:
Blood Urea Nitrogen (BUN):  This is the amount of protein in the blood that comes from the waste product urea. If the kidneys are not able to remove urea from the blood normally, the BUN level rises. Normally BUN is 6-31 in a dog, and 14-36 in a cat.
Creatinine:  This is the best test to evaluate how the kidneys are functioning.  The normal creatinine in a dog is 0.5 – 1.5, and 0.6 – 2.4 in a cat.
Urine Specific Gravity:  This is a measurement of the concentration of the urine.  One of the kidney’s most important jobs is to conserve the body’s water. A failing kidney cannot make concentrated urine. 

There are many additional tests that can be helpful in evaluating how the kidneys are performing including phosphorus (which elevates when the kidneys are failing), calcium, potassium, hematocrit (a measure of red blood cell amount), blood pressure, and urinary protein.

In August, 2009, we noticed Kasey was not feeling well.  I checked her blood tests and found that she had a creatinine of 4.6 and a BUN of 86.  These tests were quite a bit above normal indicating that her kidneys were not functioning normally.  Kasey also had a urinary tract infection and an elevated blood pressure. We started her on antibiotics and subcutaneous fluids. She was already eating a diet formulated for pets with poor kidney function because I was concerned for her kidney health. Kasey quickly started to feel better and soon after, when I checked her kidney tests, the creatinine was 2.6 and the BUN was 55. These tests were not normal, yet were much better. Cats with mildly elevated kidney tests appear to have a good quality of life. 

There are many treatments available when the kidneys begin to have problems. For Kasey we gave her blood pressure medication once daily. We continued to feed her Prescription K/D (kidney diet) food, both canned and dry. This food has been scientifically shown to improve quality and length of life for a dog and cat with kidney failure. This food provides:

  1. Reduced phosphorus to help maintain healthy kidney function. 
  2. Reduced levels of protein to help reduce kidney workload. 
  3. Reduced sodium to help maintain normal blood pressure. 
  4. Increased levels of omega-3 fatty acids to help blood flow to the kidneys.
  5. Increased levels of B-complex vitamins to compensate for vitamin losses in the urine.  
  6. Added antioxidants to control cell oxidation and promote a healthy immune system. 

We gave Kasey subcutaneous fluids once daily or every other day for the rest of her life.  The fluids are given underneath the skin in a “pocket” and she absorbed the fluids gradually. Fluid therapy was helpful to ensure optimal hydration since the kidneys were not able to conserve fluid for the body as well. In addition, the fluids helped to increase circulation so more toxins could be excreted from the kidneys into the urine. 

I continued to monitor Kasey’s blood tests and urine. I, like so many pet owners, was so pleased that her kidney tests and urine remained very stable for over 2 years and she truly enjoyed her later years. Kasey was an amazing cat is so many ways, including doing so well for over two years after having very elevated kidney tests.

My family and I will treasure our memories of Kasey’s wonderful long life.