Chronic Renal Failure

44 Chronic Renal Failure



Mala Erickson, Stanley I. Rubin



1. What is the definition of chronic renal failure (CRF)?

Progressive development of polyuria, abnormal but generally stable glomerular filtration rate and elevated serum creatinine, anemia, and small kidneys is unequivocally CRF.


2. What is kidney disease?
• Chronic kidney disease (CKD) is defined as the presence of structural or functional abnormalities in one or both kidneys. Kidney dysfunction usually is irreversible and slowly progressive with function remaining stable or slowly declining over months or years.

• Kidney disease should not be used synonymously with uremia or kidney failure.

• CKD is considered a leading cause of illness and death in dogs with a prevalence reported between 0.5% and 7%.

3. What is the typical signalment of dogs affected by chronic renal failure?

CRF is often considered to occur in older animals, but surveys have shown a mean age of 6.5 to 7 years of age. CRF is considered the most common renal disease in dogs and cats.


4. What are the causes of CRD?
• Congenital and familial causes of CRF reported in Basenji, Bull Terriers, Cairn Terriers, Chow, German Shepherd, Miniature Schnauzer, Standard Poodle, Welsh Corgi, Norwegian Elkhounds, Cocker Spaniels, Samoyeds, Lhasa Apso, Shih Tzu, Beagles, Keeshonden, Golden Retrievers, Blue Merle Collies, Shar-Pei, and Soft-Coated Wheaten Terriers.

• For rational clinical management, the possible causes of CRF that are important to identify are the following:
• Infection, particularly bacterial infection.

• Chronic partial obstruction of the excretory pathway.

• Subacute to chronic nephrotoxins (e.g., hypercalcemia).

• The causes of CRF are numerous, multifactorial, and frequently impossible to determine at the end stage of the disease.

5. What is the clinical course of chronic renal failure?
• In most instances, CRF is the result of a disease that gradually reduces the number of functioning nephrons.

• Surviving nephrons hypertrophy and adaptively change their functional performance in predictable ways that tend to preserve homeostasis.

• Eventually, the consequences of adaptations to maintain homeostasis become noticeable and ordinary measures of renal function become abnormal.

• The earliest change is impaired urine concentrating ability.

• Additional loss of nephrons reduces glomerular filtration rate further and causes azotemia to prevail.

• When the combination of severity and duration of impaired renal function becomes sufficient, signs of an illness (e.g., uremia) develop.

• A rapid or abrupt deterioration in the animal’s clinical status may occur.

• Such a “uremic crisis” is characterized by severe azotemia and intensification of uremic signs. Usually, uremic crises are precipitated by changes in extrarenal factors that may be reversible (e.g., dietary indiscretion, water deprivation, vomiting).

• Progressive deterioration of intrinsic functional capacity of the remnant kidneys generally occurs.

• Eventually, residual renal function will be insufficient to sustain life, and a terminal uremic crisis will occur in most cases.

6. What are the sequential stages of renal disease leading to CRF?
1. Kidney disease without insufficiency

2. Kidney insufficiency without failure

3. Kidney failure without uremia

4. Kidney failure with mild to moderate yet stable uremia

5. Uremic crisis of CRF

6. Progression to end stage

7. Death

7. What is azotemia?
• Existence of abnormally high concentration of nonprotein nitrogenous substances (urea, creatinine, and others) in the extracellular fluids, regardless of cause.

• Because nonprotein nitrogenous compounds (including urea and creatinine) are endogenous substances, abnormally elevated concentrations in the serum may be caused by an increased rate of production (by the liver for urea; muscle for creatinine) or by a decreased rate of excretion (primarily by the kidneys).

• Azotemia is a laboratory finding.

• Azotemia may or may not be caused by renal disease; it may be prerenal or postrenal instead of renal in origin.

8. What is uremia?
• Abnormal quantities of urine constituents in the blood caused by the inability to form and excrete urine adequately, and the polysystemic toxic syndrome that occurs as a result of abnormal renal function.

• Uremia is a clinical illness.

• Uremia may or may not be caused by renal disease; it may be postrenal, or occasionally prerenal, instead of renal in origin.

• All uremic animals have azotemia, but some azotemic animals do not have uremia.

• The clinical signs of uremia are nonspecific or gastrointestinal, but a great variety of other clinical signs are observed sometimes.

9. What are the typical clinical findings in a dog with chronic renal failure?
• The onset and range of clinical signs and biochemical events in dogs with CRF may vary depending on cause, severity, duration, rate of progression of uremic state, presence of concurrent disease and the age of the dog.

• Presenting signs may be grouped into a number of organ systems/signs:
1. Gastrointestinal; anorexia, vomiting, diarrhea

2. Impaired urine concentrating ability, polydipsia, polyuria, nocturia

3. Arterial hypertension

4. Neuromuscular consequences

5. Ocular consequences

6. Hemorrhagic consequences

10. What are the typical physical examination findings in a dog with CRF?
• Extreme variability in findings

• Loss of body condition with a historical or detectable loss of body weight

• Hair coat is coarse and lusterless

• Dehydration

• Pale mucous membranes

• Fetid or ammoniacal breath

• On occasion with profound uremia, necrosis of tip of tongue

• Cardiac arrhythmias associated with electrolyte disturbances of advanced uremia

• Tachypnea, associated with metabolic acidosis

• Small, firm kidneys

• Hypothermia

11. What are the typical laboratory abnormalities in CRF?
• Nonregenerative anemia: a progressive hypoproliferative anemia is characteristic of dogs with moderate to advanced CRF

• Stress leukogram

• Hemostatic abnormalities from defective platelet function manifest by prolonged bleeding time

• Azotemia; elevated serum creatinine and blood urea nitrogen

• Hyperphosphatemia

• Metabolic acidosis

• Moderate hyperamylasemia (two to three times normal) and moderate hyperlipasemia (two to four times normal)

• Isosthenuria with inactive urine sediment

• Radiography may reveal small kidneys and osteodystrophy

12. What is microalbuminuria?
• A screening test.
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Jul 31, 2016 | Posted by in INTERNAL MEDICINE | Comments Off on Chronic Renal Failure

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