KIDNEY DISEASE
Chronic renal failure (CRF), or long term kidney disease, is one of the most common medical problems seen in older dogs and cats, and can be seen in young animals as well. All old pets (over about nine or ten years of age) have some degree of kidney damage, but signs of kidney failure do not develop until about two thirds of the kidneys' tissues are damaged. When this two thirds level is reached, the kidneys can no longer remove waste materials from the body properly, nor can they conserve water and electrolytes (sodium, potassium, chloride etc.) to maintain the correct levels in the blood.
There are many causes of kidney disease in addition to age related deterioration. Some of the most common include bacterial and viral infections, poisons, tumors, injuries and parasites. Kidney disease often occurs as a result of infections in other areas of the body such as the bladder, uterus, lungs, and especially infected teeth. Kidney failure also may occur when a pet goes into shock following an accident or serious illness.
To confirm a diagnosis of kidney disease the veterinarian will need to examine blood and urine specimens. X-rays may also be necessary. These tests will help your veterinarian to determine the cause and severity of the disease, so that the best treatment can be chosen. It is often not possible for your veterinarian to determine the exact cause of a dog or cat's kidney problems, especially if the disease has been present for a number of years.
COMPENSATED KIDNEY FAILURE: If the kidney failure is not severe, the pet can compensate by drinking extra water and producing more urine. In this way waste materials are literally flushed out of the body. Unfortunately, needed chemicals such as potassium can also be flushed out to some degree. Except for increased thirst and excessive urination, the dog or cat remains relatively healthy. This is called compensated kidney failure.
Signs of compensated kidney failure include: Increased thirst, increased urination, increased hunger, intermittent vomiting, minor digestive upsets, dry skin.
UNCOMPENSATED KIDNEY FAILURE: If the kidney failure is severe, due to an acute (sudden) kidney disease or worsening of a chronic (longstanding) kidney disease, the dog or cat will become unable to drink enough water to flush out waste materials. The kidneys will also be unable to pass back needed water and
chemicals to the body. This condition is called uncompensated kidney failure. Uncompensated kidney failure leads to uremia, a condition in which poisonous waste products accumulate in the body, and body fluids and electrolytes are not kept in balance. This is a serious and life-threatening condition, which may require intensive hospital care.
Signs of uremia include:
Increased thirst; apathy; depression; listlessness; reddened eyes; skin problems; excessive or no urine production, depending on the stage of the disease; dehydration; pain; vomiting; diarrhea; loss of appetite; emaciation; bad breath; mouth ulcers; discolored tongue; muscle twitching; coma; and eventually death.
The severity of these signs depends on whether the uremia develops quickly or slowly, and how severe the kidney impairment is. There is no cure for chronic kidney disease, but treatment can prolong your pet's life, sometimes for many years. The objectives of kidney treatment are to:
1. Assist the failing kidneys in eliminating waste materials by liquid intake control -- fresh water should always be available, and drinking should be encouraged.
2. Decrease the amount of waste materials to be eliminated by the kidneys by diet control -- special diets are fed containing the minimum amount of the highest quality protein, to reduce the load of protein waste products on the failing kidneys.
3. Replacing fluids, electrolytes and vitamins lost due to the increased amounts of urine excreted by the kidneys. In acute cases this may be done in the hospital with intravenous fluids. We also often train owners to give their pets subcutaneous (under the skin) fluids at home. Depending on the severity of the kidney disease this may be needed anywhere from once a week to twice a day, and it takes about ten minutes each time.
4. Minimizing damage from infections elsewhere in the body, such as infected teeth. Dental disease is the biggest contributing factor to kidney disease, so regular dental care is very important.
5. If necessary, managing dry skin, vomiting, high blood pressure and other secondary problems with medication. Blood pressure should be monitored regularly - high blood pressure secondary to chronic kidney disease can cause blindness and strokes. Click here for more information on high blood pressure (hypertension).
The aim of treating a dog or cat with chronic kidney failure is to keep the pet in a compensated condition; that is, a bodily balance whereby the kidneys are still able to remove waste materials because the pet is drinking and urinating more, and complications are minimized.
The owner who accomplishes these goals can keep a treasured pet alive and happy, with minimal expense and inconvenience, sometimes for many years. However, the disease is progressive and eventually the body will not be able to compensate. At this stage of chronic kidney disease the pet will have so little functioning kidney left, that even with intensive care, the dog or cat will not recover from the inevitable uremic crisis. At this point euthanasia is usually warranted to prevent further suffering by the pet.
Early detection and control are the keys to maximizing the lifespan of a patient with kidney disease. A yearly urine check on any aging pet is a wise idea. You can catch a urine sample from your dog yourself using a clean cup or pie pan. The urine sample should then be transferred to a clean jar or plastic container, with a lid, and stored in the refrigerator until it is brought to the clinic. Cats are a little more difficult to get urine specimens from. Special litter is usually needed or you can have your veterinarian obtain the sample at the veterinary clinic.
Annual or semi-annual blood testing is recommended once your pet reaches geriatric age. If kidney disease is detected, the treatment and frequency of follow up blood and urine tests depends on the stage of the disease.
We usually divide kidney disease into three stages, although sometimes there is overlap between the stages. Here are typical recommendations for care at each stage.
Stage 1: Urine is becoming dilute but blood tests are still within the normal range
Blood and urine testing annually
K/D or an equivalent prescription diet made for kidney disease
Dental care as needed, usually with SQ or IV fluid support
Stage 2: Urine is not being concentrated, creatinine less than 3 in cats and less than 2.5 in dogs
Blood and urine testing twice yearly
K/D or equivalent prescription diet
Dental care as needed, with IV fluid support
Twice yearly blood pressure checks
Stage 3: Creatinine above 3 in cats, above 2.5 in dogs
Blood testing quarterly
K/D or equivalent prescription diet
Dental care if health permits
Twice yearly blood pressure checks if blood pressure is normal, quarterly if on blood pressure medication
SQ fluids administered at home if owners are able and willing
Medication may be necessary for vomiting or other problems
Acute renal failure, or sudden worsening of chronic renal failure, may require hospitalization and fluid therapy. Once stabilized the pet will then fall into one of these three categories for long term maintenance at home. Most pets, unless their life is shortened by other diseases, will gradually progress through all 3 stages.
Common problems of pets with advanced kidney disease include:
1) potassium deficiency, treated with an oral supplement (the kidneys lose potassium in the urine when not functioning properly);
2) high phosphorus blood levels (the kidneys are supposed to excrete excess phosphorus in the urine), treated with antacids that bind to phosphorus in the intestinal tract;
3) anemia (the kidneys should monitor the blood passing through them and send a hormone to the bone marrow that instructs the marrow to make more red blood cells), treated with injections of artificial hormone;
4) hypertension (high blood pressure) that requires medication (the hormone listed above cannot be used if hypertension exists);
5) dehydration - despite increased water consumption, most CRF patients cannot drink enough to make up for what they lose in the urine. Many owners learn how to give injections of fluids under the skin of the pet as needed - anywhere from once a week to twice a day. Replacing lost fluid and electrolytes as needed can prolong life expectancy literally by years. The procedure to do this is quick and almost painless. Many pets tolerate it extremely well.
6) vomiting or diarrhea caused by the build-up of toxins that the kidneys are not effectively excreting from the body, treated with antiemetics and antacids.
7) dry skin and weight loss due to poor appetite and loss of nutrients in the urine. Nutritional supplements are helpful, especially fatty acids and B vitamins.
In the early stages of CRF, the extra care your pet will need is minimal. In the later stages a significant commitment is needed on the part of the owner, as well as the veterinary team, to work together to support the health and happiness of the pet as long as possible.
