Renal Failure, Chronic (Feline)
| PrintChronic renal failure (CRF) is an irreversible but often slowly progressing condition that is managed rather than cured. The goal of treatment is to slow the progress of the disease and to minimize changes in other body systems.
Common name: Chronic renal failure
Scientific name: Chronic renal failure
Diagnosis
Signalment
All cats are susceptible to developing the disease, but middle-aged and older cats are more often affected.
Incidence/prevalence
CRF is one of the most common chronic illnesses affecting cats and one of the most common causes of death in elderly cats.
Geographic distribution
There is no geographic contribution to CRF in cats.
Clinical signs (primary, most to least frequent, scientific term, synonyms)
Increase in urine production and water consumption (polyuria and polydipsia), Lethargy or decrease in normal activity levels, Loss of appetite (anorexia) and weight loss.
Clinical signs (secondary, most to least frequent, scientific term, synonyms)
Vomiting, ulcers or sores in the mouth (stomatitis and glossitis), Secondary changes can include change in bone density and loss of teeth.
Causes (scientific, common term): Hypertension (high blood pressure)
Immune mediated (the immune system starts to attack tissues in the body), Neoplasia (cancer cells may originate in the kidneys or spread from other organs).
Organ systems affected (most to least affected)
Kidneys, Gastrointestinal tract (can see sores in mouth, vomiting), Hematologic (blood); often see anemia (low blood count) leading to weakness, Musculoskeletal (can lose muscle mass).
Diagnostic tests
Blood tests (measure normal body wastes that may build up, including blood urea nitrogen, or BUN, and creatinine; when these levels go up, it is called azotemia or uremia), Urine specific gravity (in CRF, the urine is more dilute), Urine protein (protein often leaks through along with wastes).
Differential Diagnosis
Diabetes mellitus (may also cause increase in urine and thirst), Neoplasia (cancer); may see weight loss and wasting appearance.
Overview
The kidneys are composed of millions of individual filtering units (nephrons). Each nephron has a filtering part, called a glomerulus, and tubules where water and other substances are reabsorbed. Chronic renal failure (CRF), which can affect cats of all ages, may develop as a result of many different insults to the kidney – including infections, abnormalities of the immune system, kidney stones and toxins – and may originate in different regions of the nephron. Often the initial insult is never determined.
When one part of a nephron is damaged beyond repair, the rest of that unit will degenerate. As more of the nephrons disappear, the kidneys often become smaller and firmer. After a majority of the nephrons have been damaged, CRF starts to develop. Early CRF may be detected by blood and urine tests, before there are any outward signs.
At first, CRF may be subtle; cats may start to sleep more or move around less. If clumping litter is used, the size of the urine clumps increases. The water bowl may start to run dry. Later, decreased appetite and weight loss are noted. Bad breath may have an “ammonia” smell.
Diagnosis is based on history, physical examination, blood chemistry tests, and urinalysis. The kidneys may be smaller than normal and feel firm. Azotemia (a buildup of blood urea nitrogen, or BUN, and creatinine normally removed by the kidneys) is most common. Potassium is often low, while phosphorus may be too high. Urine is diluted because excess fluid is not removed in the tubules of the nephron. Dehydration may cause skin to feel thicker or stiffer than normal.
Treatment
Professional care
Initial treatment most often involves intravenous (IV) fluids, given through a catheter inserted into a vein. The goal is to decrease the BUN and creatinine while balancing electrolytes and getting control of hypertension.
Home care
Once a cat with CRF is stabilized, the challenge is for owner and veterinarian to plan home care to maintain a more normal state and to try to slow the progression of CRF. Kidney diets often restrict protein; supplements to add potassium and decrease phosphorus absorption from the GI tract can help. Regular medication to control blood pressure can help slow loss of protein through the kidney. Since there is still excess fluid loss, owners often learn how to give fluids by injection just under the skin. This prevents dehydration since a cat cannot keep up with fluid needs by drinking alone.
Action
After diagnosis and initial treatment, management requires a cat owner and veterinarian to work closely to manage CRF. Regular blood tests are needed to assess how well treatment is working and may indicate time to change or increase medication. An owner who knows the pet can be alert to any changes in behavior that may indicate a change in status.
Outcome
CRF is a disease that is managed, trying to slow the progress and maintain good quality of life. It is not a disease that is cured.
References/Additional Readings
Brown, S.A. Chronic Renal Failure. In: Morgan, R.V., ed. Handbook of Small Animal Practice, 3rd Ed. Philadelphia: W.B. Saunders Company, 1997; 512-516.
Chew, D.J., and DiBartola, S.P. Diagnosis and Pathophysiology of Renal Disease. In:
Ettinger, S.J., ed. Textbook of Veterinary Internal Medicine, 3rd Ed. Philadelphia: W.B Saunders Company, 1989; 1920-1926.
James, KM. Medical Management of Chronic Renal Failure. In: August JR, ed. Consultations in Feline Internal Medicine 4. Philadelphia: W.B. Saunders Company, 2001; 328-336
Langston, C. Chronic Renal Failure, Occult (Asymptomatic) and Chronic Renal Failure, Overt (Symptomatic). In: Cote, E., ed. Clinical Veterinary Advisor, Dogs and Cats. St. Louis: Mosby Elsevier, 2007; 204-207.
Author
Mary M. Schell, DVM
DABVT, DABT
Editor
Steven Hansen, DVM, MS, MBA
DABVT, DABT
© 2007. The American Society for the Prevention of Cruelty to Animals (ASPCA)
Please note that PetVet should only be used as a guide and in no way should be substituted for licensed veterinary care.
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