Chronic Renal (Kidney) Failure in Cats

Overview of Chronic Kidney Failure in Cats

Chronic renal (kidney) failure (CRF) is a common problem in all cat breeds. The digestion of food produces waste products, which are carried by blood to the kidneys to be filtered and excreted in the form of urine. When the kidneys fail, they are no longer able to remove these waste products, and toxins build up in the blood producing clinical signs of kidney disease.

Below is an overview of Chronic Renal (Kidney) Failure in Cats followed by in-depth detailed information about the causes, diagnosis and treatment of this disease.

CRF affects all breeds of any age, although older pets are commonly affected, as the prevalence increases with age. The average age of diagnosis in cats is nine years. Breeds thought to be more susceptible include Abyssinians and Persians. CRF affects almost every body system causing many changes throughout the body and usually results in the following:

• Abnormal filtration of blood and retention of waste materials
• Failure of hormone production (including substances that stimulates the production of red blood cells [erythropoeitin])
• Disturbance of fluid, electrolyte and acid-base balance
• CRF can be caused by several different processes. These may include diseases, some of which can be secondary to other disease processes or trauma, that may have caused acute kidney failure such as:
• Toxins
• Poor blood flow and lack of oxygen (ischemia)
• Inflammatory disease
• Infections
• Cancer (neoplasia)
• Immune system abnormalities

What to Watch For

• Excessive drinking and urinating (Note – Increased urination is sometimes noted as pet using the litter box more frequently, urinating in abnormal places in the house or increased weight of the litter box)
• Lethargy or fatigue
• Vomiting
• Halitosis (Bad Breath) in Cats
• Poor appetite
• Weakness
• Lack of coordination when walking
• Weight loss

Diagnosis of Chronic Kidney Failure in Cats

Diagnostic tests are needed to recognize CRF and exclude other diseases. These tests may include:

• Complete medical history
• Complete physical examination
• Blood tests such as biochemistry analysis and a complete blood count (CBC)
• Urinalysis
• Abdominal radiographs (X-rays)

Treatment of Chronic Kidney Failure in Cats

Although there is no cure, early detection can slow the progression of the disease. CRF can be a life threatening condition that requires hospitalization and treatment for stabilization in extremely ill pets. Treatments may include:

• Fluid therapy for dehydrated pets
• Management of blood abnormalities such as hyperkalemia or hypokalemia (abnormal potassium blood levels), metabolic acidosis and hyperphosphatemia
• Dietary therapy with protein a phosphorus restriction
• Free access to water
• Supportive care and careful monitoring of urine output
• Control of vomiting with diet and drug therapy as needed
• Management of anemia if needed (with Epogen)

Home Care

Chronic renal failure is life-threatening, and if you suspect your pet has this condition, you should see your veterinarian as soon as possible. Follow-up with your veterinarian for examinations, laboratory work and urinalysis. Blood and urine analysis should be repeated within five to seven days after discharge.

Feed your pet the diet recommended by your veterinarian. Provide free access to fresh clean water at all times. Some owners can administer subcutaneous fluid to their pets at home, if necessary. Your veterinarian can provide instructions when indicated.

Administer any prescribed medications as directed by your veterinarian. Drug therapy may include: phosphate binders; potassium supplementation; or drugs for vomiting (such as cimetidine or famotidine); or anabolic steroids for some patients. Epogen may be given for anemia two to three times weekly.

Preventive Care

There are no specific recommendations for prevention of chronic renal failure. However, general suggestions include:

• Providing frequent attempts to urinate and free access to fresh clean water.
• Avoiding exposure to ethylene glycol and toxic plants (such as Easter lily) that can cause acute kidney damage.

In-depth Information on Chronic Kidney Failure in Cats

Other medical problems can lead to symptoms similar to those encountered in CRF. Laboratory testing (blood work and urinalysis testing) will often diagnose CRF. Further diagnostic testing may be needed to determine the underlying cause.

Diseases that can appear similar to those with CRF include:

• Acromegaly (abnormal enlargement of of the extremities of the skeleton due to overgrowth of connective tissue)
• Acute Renal (Kidney) Failure (sudden onset of kidney failure)
• Diabetes Mellitus(malfunction of the pancreas, whose function is the production and release of insulin)
• Diuretic phase of acute renal failure (ARF)
• Drugs (diuretics, corticosteroids)
• Excessive parenteral fluid administration
• Hyperadrenocorticism (Cushing’s Syndrome)
• Hypercalcemia (High blood calcium)
• Hyperthyroidism (excessive functional activity of the thyroid gland)
• Hypokalemia (low blood potassium)
• Liver disease
• Multiple myeloma (cancer)
• Nephrogenic (producing kidney tissue) diabetes insipidus (a metabolic disorder, which results in a deficient quantity of the hormone ADH being released or produced, resulting in failure of reabsorption of water in the kidney
• Partial Urinary tract obstruction
• Polycythemia (an increase in the circulating red blood cell mass)
• Post-obstructive diuresis (an increased excretion of the urine due to the diuretic effect of urea and electrolytes retained during the period of obstruction)
• Primary hyperparathyroidism (abnormally increased activity of the parathyroid gland)
• Psychogenic polydipsia (excessive drinking caused by psychological causes, such as boredom)
• Pyelonephritis (inflammation of the kidney and renal pelvis)
• Pyometra (infection of the uterus)
• Renal glucosuria (the presence of sugar in the urine)
• Renal medullary (central or inner portion of an organ) washout of solute
• Salt administration

Causes of Kidney Failure in Cats

• Chronic interstitial nephritis of unknown cause (most common)
• Renal (Kidney) AmyloidosisAmyloidosis (familial in Abyssinian cats)
• Chronic glomerulonephritis
• Chronic obstructive uropathy (hydronephrosis)
• Chronic Pyelonephritis
• Feline infectious peritonitis (FIP) is an inflammation of the membrane lining the the walls of the abdominal and pelvic cavities.
• Acute renal failure
• Cancer (kidney lymphoma)
• Polycystic kidney disease (PKD) (familiar in Persian cats)

Veterinary care should include diagnostic tests and subsequent treatment recommendations.

Diagnosis In-depth

Diagnostic tests must be performed to confirm the diagnosis of CRF and exclude other diseases that may cause similar symptoms. Tests may include:

• Your veterinarian should perform a complete medical history and a thorough physical examination.
• Complete blood count (Hemogram; CBC) may be performed to evaluate for signs of infection, inflammation, anemia or platelet abnormalities. Performing a buccal mucosal bleeding time may best assesses abnormal platelet function.
• A biochemistry analysis (biochemical profile tests), such as serum creatinine and BUN concentrations are typically elevated with CRF. Serum phosphorus and potassium concentrations may also be increased.
• Urinalysis tests may show a low specific gravity, which is common with CRF. Abnormal urine protein or sediment may indicate infection or glomerular disease.
• Abdominal radiographs (X-rays) may show small kidney size, which is common with CRF, but normal renal size does not rule out CRF. Some chronic kidney diseases in cats can be associated with enlarged kidneys (e.g. polycystic renal disease, renal lymphoma).
• Other diagnostic tests may be recommended on a case-by-case basis. Tests may include:
• Renal ultrasounography can provide additional information about the kidneys. Kidneys with chronic disease are typically small and sometimes irregularly shaped. Large kidneys may indicate polycystic renal disease, cancer or an acute kidney disease. Some pets can have a normal ultrasound with CRF.
• Excretory urography may be useful in the evaluation of abnormalities in renal size, shape or location. It may also be valuable in the detection of obstruction, cancer or stones.
• Urine culture should be performed to evaluate for the presence of upper or lower urinary tract infection.
• Blood gas analysis will allow evaluation of acid base levels.
• Leptospira antibody serologic tests may be needed to diagnosis this infection.
• Arterial blood pressure may be needed to determine the presence of complicating hypertension (high blood pressure).
• A fine need aspirate (biopsy) of the kidney may be useful in some cats with renal diseases (e.g. kidney lymphoma, granulomatous interstitial nephritis due to FIP).
• Endogenous or exogenous creatinine clearance can be used to measure glomerular filtration rate in pets with normal blood work who are suspected to have renal disease.
• Urine protein/creatinine ratio is useful to evaluate urinary protein loss in pets suspected to have glomerular disease.
• Fractional excretion of electrolytes (sodium, potassium, chloride, and phosphorus) may be useful in evaluation of animals with suspected renal tubular disorders.
• Radioisotope clearances may be used to determine kidney filtration and blood flow.

Treatment In-depth

Treatment of chronic kidney failure must be individualized based on the severity of the condition, the cause, secondary diseases or conditions and other factors that must be analyzed by your veterinarian. A search for reversible causes of kidney failure should be completed. The ultimate goal of the management of CRF is to provide supportive care while trying to treat/eliminate secondary factors aggravating kidney failure such as, infections, dehydration, malnutrition, anemia, etc.

• Fluid therapy is important to correct dehydration and abnormalities in serum electrolytes. Care must be taken to avoid over-hydrating the patient, because the kidneys may not be able to produce urine to get rid of the excess fluid.
• Dietary therapy may include a diet that is low in protein and phosphorus. Special diets are formulated for pets with chronic renal failure such as Prescription diet k/d, CNM NF-FORMULA, Eukanuba Nutritional Kidney Formulas, IVD Modified.
• Management of abnormal blood potassium may be done. The level may be low or high (with late stage of kidney failure). Correction of metabolic acidosis may be performed by treating the problem with sodium bicarbonate if needed.
• Elevated phosphorus may be treated with intestinal phosphorus binders such as aluminum hydroxide and aluminum carbonate.
• Control of vomiting may be treated with drugs that may beneficial, including: cimetidine (Tagamet®), ranitidine (Zantac®) or famotidine (Pepcid®).
• Anabolic steroids are available, but there are no long-term studies demonstrating their efficacy.
• Anemia may be treated with recombinant human erythropoietin. Cats treated with Epogen have demonstrated resolution of anemia, weight gain, improved appetite, improved haircoat and improved sociability with their owners. There are some risks associated with its use.
• Vitamin D (calcitriol or 1,25-dihydroxycholecalciferol) may be supplemented (as Calcitriol synthesis is impaired with CRF). The benefits of supplementation are controversial. Calcitriol must only be used after hyperphosphatemia has been adequately controlled.
• Patient monitoring is an important part of continuing optimal treatment. Monitoring may include the following: serial body weight (to determinations facilitate proper fluid therapy); measurement of urine output; packed cell volume (PCV) and total plasma proteins (will help monitor fluid load); and serial determinations of serum biochemistry are necessary to determine if the animal is responding to treatment. These determinants will help determine the proper fluid and drug therapy.
• Treatment may be required from three to five days, depending on the response and secondary causes. If treatment fails, dialysis or kidney transplant may be a treatment possibility. Referral may be required for dialysis treatment. CRF may be progressive despite treatment. The prognosis for recovery of renal function depends on the severity of the kidney lesions and the cause of CRF. Euthanasia may be considered for pets that do not respond to treatment.

Kidney transplantation has been done successfully but is cost prohibitive for most cat owners. The cost according to the University of California Davis College of Veterinary Medicine is approximately $18,000 to $24,000. Average life span post transfusion is 3 to 6 years.

Follow-up Care for Cats with Chronic Kidney Failure

Optimal treatment for your pet requires a combination of home and professional veterinary care. Specific instruction for home therapy is determined by renal damage. Follow-up can be critical and may include:

• Administer any veterinary prescribed medications as directed, and be certain to contact your veterinarian if you are experiencing problems treating your pet.
• Follow-up with your veterinarian for examinations, laboratory work and urinalysis. Blood and urine analysis should be repeated within five to seven days after discharge.
• Some owners can administer subcutaneous fluid to their pets at home. Your veterinarian can provide instructions when indicated.
• Feed the diet recommended by your veterinarian. Provide your pet free access to fresh clean water at all times.