Overview of Canine Chronic Renal Failure (CRF)
Chronic renal failure, commonly referred to also as chronic kidney failure and abbreviated as CRF, is a common problem in all dog 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.
All breeds of any age can be affected. However, older pets are commonly affected as the prevalence increases with age. The average age of diagnosis in dogs is seven years.
Dog breeds thought to be more susceptible include:
Soft-coated wheaten terrier
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:
Poor blood flow and lack of oxygen (ischemia)
Immune system abnormalities.
What to Watch For
Signs of chronic renal failure in dogs may include:
Lack of coordination when walking
Diagnosis of Chronic Renal Failure in Dogs
Diagnostic tests are needed to recognize CRF and exclude other diseases. Tests may include:
Complete medical history and physical examination
Complete medical history including questions regarding change in water consumption and urination, exposure to ethylene glycol (antifreeze), recent surgery or anesthesia, drug therapy, appetite, weight loss, previous illness, and medications
Complete physical examination
Complete blood count (CBC)
Other diagnostic tests may include:
Blood gas analysis
Endogenous or exogenous creatinine clearance
Urine protein/creatinine ratio
A fine needle aspirate
Fractional excretion of electrolyte
Treatment of Chronic Renal (Kidney) Failure in Dogs
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)
Chronic renal failure is life-threatening, and if you suspect your dog 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 dog 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.
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 that can cause acute kidney damage.
In-depth Information on Chronic Renal Failure in Dogs
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 failure (sudden onset of kidney failure)
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)
Diabetes mellitus (malfunction of the pancreas, whose function is the production and release of insulin)
Drugs (diuretics, corticosteroids)
Excessive parenteral fluid administration
Hyperadrenocorticism (Cushing’s disease)
Hypercalcemia (high blood calcium)
Hypoadrenocorticism (Addison’s disease)
Hypokalemia (low blood potassium)
Multiple myeloma (cancer)
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 (uterine infection of intact dogs)
Renal glucosuria (the presence of sugar in the urine)
Causes of Chronic Renal Failure in Dogs
Chronic interstitial nephritis (inflammation of the kidney) of unknown cause (most common)
Amyloidosis (when the protein amyloid is deposited in various tissues tissues become waxy and nonfunctioning)
Chronic glomerulonephritis (a variety of nephritis)
Chronic obstructive uropathy (any disease in the urinary tract)
Chronic pyelonephritis (inflammation of the kidney and renal pelvis)
Familial renal disease (disease pets can be born with such as in cocker spaniel, Lhasa apso, shih tzu, Norwegian elkhound, Samoyed, Doberman pinscher, soft-coated wheaten terrier, bull terrier, golden retriever, and others)
From acute renal failure
Hypercalcemic nephropathy (caused by high blood calcium)
Leptospirosis (an infectious disease of all species)
Cancer of the kidney
Veterinary care should include diagnostic tests and subsequent treatment recommendations.
In-depth Information on Diagnosis
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.
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.
Other diagnostic tests may be recommended on a case-by-case basis.
Tests may include:
Kidney ultrasonography 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 disturbances.
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).
Endogenous or exogenous creatinine clearance can be used to measure glomerular filtration rate in pets with normal blood work and 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.
In-depth Information on Treatment
Treatment of chronic renal failure in dogs 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 and eliminate secondary factors aggravating kidney failure such as, infections, dehydration, malnutrition, anemia, etc.
Treatments for CRF may include:
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 u/d, CNM NF-FORMULA, Eukanuba Nutritional Kidney Formula/Early Stage/Canine, Eukanuba Nutritional Kidney Formula/Advanced Stage/Canine, 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. Dogs 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 renal lesions and the cause of CRF. Euthanasia may be considered for pets that do not respond to treatment.
Follow-up Care for Dogs with Chronic Renal Failure
Optimal treatment for your dog requires a combination of home and professional veterinary care. Specific instruction for home therapy is determined by kidney 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.