CHRONIC KIDNEY DISEASE
Normal kidneys filter the blood, removing wastes produced by the body and excreting them in the urine. Kidneys are also responsible for homeostasis that controls hydration, body temperature, and blood protein and electrolyte levels. Levels of electrolytes such as Sodium, Potassium, Calcium and Phosphorus are involved in multiple tasks in the body, including function of the heart. Another function of the kidneys is to produce a hormone that controls bone marrow in production of red blood cells. Without this hormone, the animal will eventually have a decreased number of red blood cells, a condition we call anemia.
Kidneys are damaged in a variety of ways. The kidneys may suffer by dehydration, heat, infection, toxic substances, inflammation, neoplasia (cancer) and/or excess protein metabolism. Kidney cells may become damaged and become nonfunctional over a period of years. About three-fourths of kidney tissue must be damaged before significant signs of illness appear. For this reason, kidney disease is often considered chronic (present a long time) even though the affected pet may not have shown signs of disease for very long.
Every day for the last few days, weeks or months your pet's kidneys have not been functioning properly. Cellular wastes have not been fully excreted into the urine allowing the waste products to accumulate in the bloodstream creating toxic levels. Continued re-circulation of this toxic buildup results in illness as these wastes are damaging to many tissues in the body and the kidneys themselves. The central nervous system is affected by toxic buildup and dehydration many times causing a depression.
Hopefully, yearly blood analysis has been performed and has allowed diagnosis of this condition before the pet becomes clinically ill from it. Increased urination and drinking water may be the only signs found. This is caused by the kidney's now decreased ability to concentrate the urine and maintain hydration. Since urine is now more diluted, the animal needs to drink more to maintain hydration. Kidneys normally retain potassium and protein and excrete sodium and phosphorus. When they are not functioning, potassium and protein are lost. Potassium is important in controlling the muscles ability to contract. The heart is a muscle. Many of these pets lose muscle mass to make up to the blood stream for the protein that was lost into the urine. The muscles waste. This is part of the cause for lethargy, inactivity, and certain postures are common with electrolyte imbalance. The muscles are more likely to atrophy. The animals become weak. Potassium is depleted further by vomiting, and by not eating.
Signs of chronic kidney disease can include lethargy, weight loss, increased thirst, increased urination, decreased appetite, nausea, heat seeking, and bad breath. As the disease progresses and the pet becomes toxic by buildup of body wastes, the pet may become depressed and weak, begin vomiting, and/or have diarrhea. Continued illness results in collapse, seizures, coma and death. Though chronic kidney disease is not curable, it is often controllable. Each animal will have an independent ability to respond to treatment and control or slow the progression of the disease. This is partly dependent on the number of functioning kidney cells that are remain. Although we cannot increase the number of functioning cells (without a transplant) the remaining cells have an ability to increase the work they do. Many pets can live reasonably normal lives when properly managed in a cooperative effort between owner and veterinarian. Treatment will be based on the individual animal. The sooner disease is detected, the simpler the treatment will be. Our goal is to slow the progression of the disease, but we will be unable to stop it completely. A quality life may be provided for your pet for only several weeks or for up to several years.
You have many choices to make. You do not have to elect all the recommended tests and/or treatments. However, each test and/or treatment is recommended for specific reasons and declining those and/or not following instructions may worsen your pet's condition. Some medications can only be given if regular monitoring is completed.
To try to determine the cause and monitor the progression of kidney disease a number of tests are required.
Initial diagnostic tests include:
A complete blood cell count
An organ function blood screen which includes:
Blood urea nitrogen
Serum total protein concentration
Urine tests include:
Urinalysis to establish diagnosis and identify kidney complications
Urine culture to rule-out urinary tract infection
Urine protein:creatinine ratio
Survey radiographs of the abdomen and of some patients the heart and lungs
Further recommended testing may include:
Ultrasound of the kidneys
Biopsy of the kidney
or special tests for infectious diseases
After the pet is diagnosed and initial treatment recommendation are made and started we recommend regular monitoring of your pet's blood chemistries, electrolytes and complete blood cell count. This should be done at a minimum of every 6 months for pets that are maintaining their weight and appetite and organ function, and more frequently if any changes are noted in your pet.
We recommend regular monitoring of your pet's blood pressure. Initial testing should be completed then every 2-4 months if normal readings. If hypertension is diagnosed, testing will be more frequent. Pets that are hypertensive can have increased damage to their kidneys occurring. Hypertension can lead to a combination of problems including retinal detachment, blindness and heart disease to name a few. Hypertensive pets may be placed on medication to correct that condition. If your pet has not had a blood pressure check yet, please schedule this service.
Prognosis varies. Short of taking a biopsy, we have no way of determining what percentages of kidney cells are functioning or what type of damage has occurred. We measure 2 values in the bloodstream, Blood Urea Nitrogen (BUN) and Creatinine, that represent build up of waste, as well as the electrolytes and protein levels. A ratio of protein to creatinine in urine gives further information. For prognosis many factors need to be evaluated, in general the higher the BUN, Creatinine and Phosphorus, the worse the prognosis. The lower the Potassium, serum protein, body temperature and red blood cell count, the worse the prognosis. The more protein in the urine the worse the prognosis. The healthier appearing and feeling a pet is when diagnosed, the better the prognosis.
BUN should normally be between 10 and 30, with Creatinine between 1 and 3. Interpreting these values must be done in conjunction with the pet's presenting signs of illness and dehydration. The following is a table showing various values, the initial prognosis in chronic renal failure for a positive response to initial therapy, and an estimated number of days initial treatment may take.
BUN Creatinine Prognosis # Days for IV Fluids
40-50 3.5-5 Good 0-3
50-80 5-7 Good to Guarded 1-4
80-100 7-8 Guarded 2-6
100-120 8-10 Guarded to Poor 3-7
120-150 10-12 Poor to Very Poor 4-8
> 150 >11 Very Poor to Grave 5-10
Once initial values are determined, response to treatment is used to update the prognosis. The sooner the BUN and Creatinine drop, the better the prognosis. The sooner the pet is maintaining body temperature, is feeling well, and is eating well, the better the prognosis.
Important Points in Treatment
1. In many cases, initial treatment involves a forced diuresis, flushing the animal's blood with intravenous fluids. This rehydrates the pet, replenishes potassium and provides a healthier environment for the functioning kidney cells to work in. This is continued until the metabolic waste level is reduced back toward normal. Usually this is done in the hospital over a period of 3 to 10 days. Electrolytes will be tested daily, and serum chemistries tested every 2-3 days. Blood pressure will be monitored as needed. When the values of the kidney function tests are normalizing and the pet is eating well, treatment can continue at home.
2. IV fluid treatment will be specific for your pet. In some pets, fluids can be pushed faster than in other pets.
3. Potassium supplementation through addition to fluids and oral supplementation will be initiated. A potassium supplement should be given daily. Tumil K, the supplement is available in tablets, granules and a gel.
4. B Vitamins supplementation will be added to fluids, and oral vitamin supplementation is recommended. A multivitamin should be given. Pet-Tinic, Nutrical and other brands are available. For cats we recommend NuCat, a tablet that most cats will eat.
5. Over the counter Famotidine (Pepcid AC) may be used in cats at 2.5 to 5.0 mg once daily in cats. Dogs may receive 5 to 10 mg every 12 hours. The medicine may be purchased as a pediatric formula or an adult 10 mg tablet. If desired, the tablet may be crushed and administered in a slurry or in canned food. We can also request the medication be compounded by a pharmacist. Please call if you cannot administer this medication.
6. Calcitriol will be prescribed for many patients diagnosed with CRF. If we have not prepared a prescription, please be sure to ask.
7. Erythropoeitin hormone replacement will be initiated in anemic pets.
8. Anabolic steroid supplementation may be initiated in any lethargic or weak pets.
9. Subcutaneous fluids given at the clinic or at home are beneficial to pets in renal disease. This allows improved hydration, and allows pets to stay healthier and at home. You may be instructed how to administer these fluids so they can be given at home. Subcutaneous fluids are not as effective as IV fluids, and will only be recommended in pets well enough for this treatment.
10. Give all medication as directed. Call the doctor if you cannot give the medication.
11. Diet: A controlled diet is critical to successful control of the progression of chronic kidney disease. Feed your pet the recommended low protein diet. However, if your pet will not initially eat the prescription diet due either to decreased appetite from the condition or the switch in food, it is more important for your pet to first eat a palatable food. Foods to try initially include your regular old food, chicken or turkey baby food, or prescription diet "a/d". If desired, a homemade recipe is available, please call for the recipe. Once your pet is eating, a gradual switch to the recommended diet should occur over a 5-7 day period. A variety of diets are available, please ask if your pet does not eat the initial diet. We regularly prescribe a variety of renal diets for pets through VetCentric. If we have not discussed this with you, please call to have this available to you.
12. Water: Make sure your pet has free access to clean drinking water at all times. Call the doctor if your pet does not seem to be drinking adequately.
Notify the Doctor if Any of the Following Occur:
* Your pet is reluctant to eat or seems depressed.
* Your pet vomits or has diarrhea.
* Your pet faints or acts dazed or confused.
* There is a change in your pet's water intake and/or urination.