Management of Kidney Failure in Dogs and Cats

 Your animal has just been diagnosed with kidney problems, and you may be overwhelmed by just what that means and what needs to be done to help him/her cope with the disease.

TERMINOLOGY

Kidney disease indicates some degree of kidney compromise; that is, the kidneys are not working at 100% capacity. This may be from an infection, from a toxin, from trauma, or from old age. The damage that is done may or may not be reversible.

Kidney failure indicates that the kidneys are in a state of deterioration; this may be mild, moderate or severe. While this is usually a progressive disease, the rate at which the kidneys fail varies greatly with the time at which the disease is diagnosed, how aggressive the treatment is, and how well the animal responds to treatment.

Either of the above can be acute; that is, the animal has normal kidney function one day and then because of a toxin or infection, the kidneys are suddenly compromised. Usually chronic kidney failure is a slow, insidious progression of the kidney's inability to keep up with the body's needs. The latter is more common in cats and dogs.

SIGNS OF KIDNEY DISEASE OR FAILURE

Often animals live with poorly functioning kidneys for some time before they show signs that are noticed by its owner. (NOTE: the signs of increased water consumption and urine output may occur with other diseases like hyperthyroidism and diabetes). Typical signs of the disease:

Drinking a lot of water

This may be just staying at the water bowl longer to drink or seeking new sources of water such as the toilet or a dripping faucet.

Urinating a lot

Despite frequent cleanings, the litter box is always full, or a previously housetrained pet has accidents in the house, or when the dog goes out, it urinates larger volumes.

Decreased appetite

As toxins accumulate in the body, the appetite drops off so the pet becomes more and more finicky.

Weight loss

This is the result of decreased appetite, but is often inappropriately attributed to old age.

Dehydration

Even though the pet is drinking a lot, they urinate dilute urine and become dehydrated.

Constipation

As the body needs more fluid, the colon becomes deprived of it. The stool dries out and the pet becomes constipated.

Bad breath

Bad teeth can also contribute, but as toxins build up in the body, they cause a bad odor from the mouth.

Oral/stomach ulcers

Acids build up in the stomach and irritate the inside lining; this may cause vomiting and/or digested blood to appear in the stool which then takes on a dark color.

DIAGNOSIS

Suspicion of kidney disease is based on the owner's observation and the veterinarian's physical exam findings and tests that can reveal the presence and severity of disease.

Bloodwork

An explanation of what these terms, along with the normal values, is shown below. (These values are based the interpretations of IDEXX, our outside laboratory. Linda Mar Veterinary Hospital's in-house values may be slightly different.)

BUN (Blood Urea Nitrogen): one of the kidney enzymes that is increased with kidney problems. This value can also be elevated with dehydration and recent ingestion of a high protein meal. Normal values for dogs are 7-27. Normal values for cats are 17-35.

Creatinine: a more sensitive test of kidney function; commonly increased with kidney problems. Normal values for dogs are 0.4-1.8. Normal values for cats are 0.8-2.3.

Hematocrit (Packed Cell Volume, or PCV): indicative of the amount of red blood cells in the body. These cells are produced by the bone marrow when it is stimulated by a hormone called erythropoietin, made by the kidneys. When the kidneys fail, they stop making this hormone. This results in anemia. Normal values for dogs are 37-55%. Normal values for cats are 24-45%.

Albumin: one type of protein that, with some types of kidney problems, can be lost in the urine (i.e. glomerular disease.) Low blood levels of this is detrimental to the animal. Normal values for dogs are 2.6-4.3. Normal values for cats are 2.4-4.1.

Cholesterol: a type of body fat commonly elevated in animals with kidney problems. Unlike humans, it does not result in hardening of the arteries. Normal values for dogs are 86-328. Normal values for cats are 42-170.

Potassium: low blood levels, especially in cats with kidney problems, are due to the potassium being lost in the urine. Normal values for dogs are 4.0-5.6. Normal values for cats are 3.9-5.3.

Bicarbonate: this is lowered because poorly functioning kidneys create an acidic state called metabolic acidosis. Normal values for dogs are 17-24. Normal values for cats are 17-24.

Phosphorus: this component of the blood is normally eliminated through the urine. Because of poorly functioning kidneys, blood phosphorus levels can become increased and can cause problems with the body's calcium levels. This causes the animal to have a poor appetite. Normal values for dogs are 2.1-6.3. Normal values for cats are 3.3-7.5.

Urinalysis: Analyzing the urine can be helpful to check the specific gravity (the animal's ability to concentrate its urine), the presence of protein (suggestive of glomerular disease), and the presence of infection of the kidneys or the bladder.

Blood Pressure: Animals with kidney failure will commonly have elevated blood pressures. Systemic hypertension affects other organs of the body such as the heart and eyes. With the latter, sudden bleeding into the retina and retinal detachments can occur, resulting in a sudden onset of blindness. Blood pressure can be measured by use of a pressure cuff. If it is increased, medication is started to bring down the blood pressure into a more acceptable range.

TREATMENT

Fluid Replacement

Probably the most important component to treatment of kidney failure, it is important to supplement your pet's fluids even though it appears that your animal is already drinking a lot because the urine they produce is dilute, so they are constantly in a dehydrated state. Additionally, poorly functioning kidneys allow toxins to accumulate in the body. Additional fluids have a flushing action to minimize the toxic levels.

Fluids can be given in 3 ways:

Orally: Making sure that fresh, clean water is always accessible to your pet is paramount. Other types of fluids can also be given, especially to cats that like clam juice, beef or chicken broth, or the water found in canned tuna. Milk is not advised, as it is not well tolerated. Additional water can be added to a pet's regular meal, either canned and/or dry.

Subcutaneously (under the skin, or SQ): fluids are administered by placing a needle connected to an administration set (venoset) to a bag of fluids (usually, a balanced isotonic solution such as lactated ringers, but sometimes saline) and allowing the fluids to slowly enter under the skin, forming a 'hump' that is slowly absorbed by the pet. Fluids usually need to be given every other day to every day.

This can be done in the hospital, or more conveniently at home, especially for animals that need it on an on-going basis, which is the case with pets with kidney failure. Owners can become adept at this after hospital staff demonstrate the technique and instruct the client.

Intravenously (in the vein, or IV): fluids are given directly into the vein after placement of a catheter in the pet's vein, that is then taped in place This can be done only in the hospital with careful monitoring by the staff. Administration of IV fluids may be needed initially if the blood values are elevated and your pet is sick (i.e. not eating; vomiting, dehydrated) or in an animal that has been well maintained in kidney failure and then suddenly decompensates.

Diet

When foods containing meat proteins are ingested, waste products are produced. While this poses no problem for healthy kidneys, ailing kidneys allow toxins to accumulate in the body. Because of this, a low protein diet is often recommended to ease the kidneys' work. For dogs and cats, commercial diets that are low in protein are Hill's Canine K/D and Feline C/D and Purina CNM - NF, respectively. Note - these are prescription foods and thus are only available through your veterinarian.

Not as low in protein, but lower than maintenance foods, are any senior formulation of a commercial brand food. Sometimes, an easily digestible source of protein that produces minimal toxins may be needed (i.e. cottage cheese or cooked egg), especially when protein is being lost in the urine.

Medication - usually in the form of tablets to manage the effects of kidney problems. These medications include:

Blood Pressure Medications: These include enalapril (Vasotec) or amlodipine (Norvasc) or benazapril (Lotensin) to bring down blood pressure. After starting on one of these, it is important to measure the animal's response to the medication to determine if the dosage is adequate. These medications are ongoing.

Renagel: given to bind with the phosphorus that becomes excessively high with the poorly functioning kidneys. This medication may or may not be needed long term.

Antibiotics: these may occasionally be needed for treatment of kidney problems, such as infection of the kidney (pyelonephritis) or of the bladder (cystitis).

Calcitriol (Rocaltrol): this is a vitamin D analogue that helps maintain normal calcium and phosphorus balances in the body. It is often given in the food in small amounts daily. Correct dosage is important as an overdose can be detrimental to your pet. This drug is usually given on an ongoing basis.

Antacids: these act to decrease stomach acidity and decrease the occurrence of ulcers, resulting in bloody vomitus or stool. These over-the-counter drugs, such as cimetidine (Tagamet) or famotidine (Pepcid AC), can be obtained at any drugstore.

Procrit (Epogen): this hormone, normally made by the kidneys, is often lacking in patients with kidney problems. It is given as an injection under the skin, usually by the owners at home after an in-hospital demonstration. It is initially given 3 times a week for 1-2 weeks, then tapered to 2 times a week for 1-2 weeks, then one time a week for maintenance.

The rate at which the frequency is tapered depends on the animal's response, as measured by weekly monitoring of the PCV or packed cell volume. Once the PCV is at the desired level and holding, the PCV should be measured on a regular basis.

It is a safe medication; however, occasionally an animal may form antibodies against the Procrit. The antibodies destroy the animal's own red blood cells, thereby worsening the anemia. Or, in some cases, animals may respond too well and make too many red blood cells. Because of cost, this treatment is usually recommended only for cats or small dogs. This medication can be obtained from your veterinarian.

PROGNOSIS

The outcome of your pet's health depends on a variety of factors, such as what type of disease it has acquired, how severe the disease is, at what stage medical intervention was started, the aggressiveness of the treatment, and how well your pet responds.

As with many diseases, the sooner the illness is detected and steps initiated to reverse the damage or slow down its progression, the better the prognosis. It is important to work closely with your veterinarian to help your pet. Rechecks on a regular basis are important to monitor your pet's health. Its weight, blood and urine values and blood pressure levels are evaluated to determine the need for changes in therapy.

If you have any problems or questions regarding this disease, don't hesitate to ask your veterinarian.

The above is general veterinary information. Do not begin any course of treatment without consulting your regular veterinarian. All animals should be examined at least once every 12 months.

About the author:

Linda Mar Veterinary Hospital and its cat-only affiliate, Coastal Cat Clinic, are small animal practices located in Pacifica, California. To find a veterinarian or to learn more about the vet clinic and our staff, visit:[http://lindamarvet.com/]

 Linda Mar Veterinary Hospital