Note: Renal and Nephro are medical terms that refer to kidneys
This page will focus on kidney diseases in dogs and cats or what we call "Upper Urinary Tract" diseases. For information on bladder infections and other "Lower Urinary Tract" diseases, please click here to go to our pages discussing this.
Coming soon...information about Gentocin, amphotericin B, and other useful drugs known to sometimes cause harm to the kidneys.
Acute Renal Failure
Chronic Renal Failure
TEXTBOOK OF VETERINARY INTERNAL MEDICINE
Client Information Series
David J. Polzin
Renal failure (kidney failure) occurs when kidney function has deteriorated to such a degree that the kidneys can no longer perform their normal functions of excreting wastes, maintaining water and electrolyte balance, and producing hormones. Renal failure occurs in acute or chronic forms. Acute renal failure is of recent onset and is potentially reversible. In contrast, chronic renal failure has been present for months to years at the time of diagnosis and is irreversible. Dogs and cats with chronic renal failure cannot be cured, but their clinical signs can often be managed successfully.
Kidneys are composed of many small functional units called nephrons (approximately 190,000 in cats and approxi-mately 400,000 in dogs). Dogs, cats, and humans are nor-mally born with such an abundance of nephrons that signs of kidney failure do not become apparent until more than two thirds of the nephrons have been damaged.
Because of this redundant kidney tissue, it is possible to donate a kidney for transplantation and survive. On the other hand, surplus nephrons make it difficult to detect chronic kidney diseases until they are well advanced. As a consequence, chronic kidney failure is often an insidious condition that remains unrecognized until it is severe. Because kidney disease is often quite advanced at the time of initial diagnosis, the initiating cause of chronic renal failure can rarely be estab-lished. Although chronic renal failure occurs most often in older dogs and cats, renal failure is not simply a result of aging.
The earliest signs of renal failure are typically thirst (poly-dipsia) and increased urine volume (polyuria). These signs result from inability of the diseased kidneys to form concentrated urine. Other common early signs include weight loss, poor haircoat, and an increasingly selective appetite. Further decline in kidney function results in progressive inability to excrete waste products, leading to retention of toxic wastes in blood and tissues in the body. This is called uremia (literally, urine in the blood). Prominent clinical signs of uremia include loss of appetite, vomiting, ulcers in the mouth, "uremic" (foul ammonia smelling) breath, weakness, and lethargy.
Other important effects of renal failure include anemia (caused by inability of failing kidneys to produce erythropoietin, the hormone responsible for making red blood cells) and high blood pressure. Anemia worsens the weakness, lethargy, and loss of appetite of dogs and cats with chronic renal failure, and high blood pressure may cause sudden blindness, strokelike signs (such as mental dullness, sudden behavioral changes, coma, or seizures), or injury to the kidneys and heart.
Diagnosis of chronic renal failure is confirmed by laboratory evaluation of your pet's blood and urine. A urine test can help determine whether the kidneys can form concen-trated urine and provide evidence of other urinary tract problems such as urinary tract infections. Blood tests used to evaluate kidney function include blood urea nitrogen (BUN) and serum creatinine concentrations. Because the kidneys excrete urea and creatinine, increases in urine and creatinine concentrations in blood indicate decreased kidney function. These tests are usually done together because they provide different information. The serum creatinine concen-tration is the more specific test for kidney function, and treatment and other factors may influence the BUN. In addition to evaluating kidney function, other tests may be used to evaluate your pet for anemia, electrolyte and acid- base abnormalities, nutrition, and hypertension. Ultrasound examination and x-rays may also be used to evaluate kid-ney disease.
Fortunately, most dogs and cats can be treated, providing a good quality of life for months or years. Treatment for chronic renal failure is tailored to the unique clinical require-ments of each pet but may include a special diet (e.g., limiting protein, phosphorus, and salt intake); hydration ther-apy; and medications designed to control clinical signs (such as poor appetite, nausea, and vomiting), acid-base and elec-trolyte disturbances, anemia, and hypertension. Consumption of excess protein may make some pets ill because the waste products of protein metabolism are excreted by the kidneys and are retained in renal failure. Dehydration (abnormal depletion of body fluids) is a special threat to pets with renal failure, and they may deteriorate if episodes of vomiting, diarrhea, or inadequate water intake are not dealt with promptly. Water should never be withheld from dogs and cats with renal failure.
In humans, renal failure is most often managed by dialysis (hemodialysis or peritoneal dialysis) or renal transplantation. Chronic hemodialysis and peritoneal dialysis have thus far not proved to be satisfactory options for dogs and cats with chronic renal failure because they are expensive and fail to provide an acceptable quality of life. Renal transplantation is an expensive but potentially useful option for selected cats but has not met with similar success in dogs. Renal transplantation is best reserved for cats that can no longer be managed by standard medical therapy.
Links, Resources, and Misc Comments
This is slightly off subject, but did you know that lots of people drink urine?
People who drink urine...I've included some links about this intriquing subject partly because it is somewhat related to the topic of this page, but mostly because it's just sort of surprising...but in many parts of the world, urine is considered a health tonic. Here are several links to sites that promote urine drinking !
Chinese Association of Urine Therapy - established for the purpose of exchanging first hand information on urine therapy and medical research.
Skeptic's Dictionary: Urine Therapy - takes a skeptical look at using urine for health related purposes.
Urine Therapy - contains information on the benefits of urine therapy.
Urine Therapy Introduction - information from HPS Online on the medicinal use of one's own urine.
Urine Homepage - general information, world conference data, books on urine therapy, and consultation services.
The above links are all to sites about drinking your own urine. The links below are to more conventional sites about urinary tract problems in pets:
Links To Other Sites about Urinary Tract Problems in Pets