44 Chronic Renal Failure
1. What is the definition of chronic renal failure (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.
3. What is the typical signalment of dogs affected by chronic renal failure?
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:
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.
• 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.
• 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.
6. What are the sequential stages of renal disease leading to CRF?
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).
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 may or may not be caused by renal disease; it may be postrenal, or occasionally prerenal, instead of renal in origin.
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.
10. What are the typical physical examination findings in a dog with CRF?
11. What are the typical laboratory abnormalities in CRF?
• Nonregenerative anemia: a progressive hypoproliferative anemia is characteristic of dogs with moderate to advanced CRF
• Moderate hyperamylasemia (two to three times normal) and moderate hyperlipasemia (two to four times normal)
12. What is microalbuminuria?
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