Introduction
Chronic renal failure (CRF) in cats results from long-term insult to the kidneys which, over time, damages their ability to adequately concentrate urine and remove nitrogenous wastes from circulation. CRF can be present without overt clinical signs; this form usually is called renal “insufficiency” rather than renal “failure”. Unfortunately, once prolonged clinical signs appear, the kidneys normally have lost most of their ability to filter the blood, excrete the end-products of body metabolism in the urine, regulate blood pressure, contribute to red blood cell production and regulate the concentrations of hydrogen, sodium, potassium, phosphate and other electrolytes in the cat’s bodily fluids.
Symptoms of CRF in Cats
The main symptoms of chronic renal failure are a result of the cat’s body attempting to compensate for the failure of the kidneys, and to flush toxins out of the body. A drastic increase in how much water the cat drinks, and as a result increased urination, is normally one of the first symptoms a pet owner notices when their cat is suffering from chronic renal failure. Additional symptoms include lethargy, a reduced appetite, weight loss, vomiting, diarrhea, and bad breath. In severe cases the blood pressure is affected, and in cases of chronic renal failure and high blood pressure the cat may go blind.
When chronic renal failure occurs, the kidneys have begun a slow decline over a long period of time. Unfortunately symptoms of chronic renal failure do not begin to appear until the kidneys are already severely damaged. While chronic renal failure can be treated it cannot be cured. As this disease is most often diagnosed in cats over 7, a yearly blood test that measures kidney function is recommended in adult and senior cats. An early diagnosis of chronic renal failure can help prevent further damage to the kidneys throu progressive treatments.
The clinical signs of chronic renal failure are largely a result of the body’s attempt to compensate for the kidneys’ inability to flush toxins out of the cat’s circulation. Among the early signs of CRF are “polyuria” and “polydipsia,” which mean dramatically increased volume of urine and excessive thirst manifested by increased water intake. Polyuria and polydipsia (also called “PU/PD”) are very commonly associated with a number of disorders in addition to renal failure and without more are not diagnostic of CRF, especially in cats who tend to develop PU/PD less commonly than dogs. Other signs that owners commonly notice are anorexia/inappetence, weight loss, vomiting, lethargy, halitosis (bad breath), seizures, bleeding/clotting problems, constipation, diarrhea, vision abnormalities and altered states of consciousness. In severe cases, affected cats can develop high blood pressure (hypertension), with the adverse effects associated with that condition.
Other signs that may be recognized by a veterinarian or by an owner are dehydration, oral ulceration (which, like the halitosis, is caused by the build-up of nitrogenous wastes in the blood), poor haircoat, poor body condition and mild pallor of the gums and other mucous membranes. The kidneys play an important role in the production and maintenance of a healthy supply of red blood cells; when the kidneys fail, that balance is disrupted and oxygen is not carried efficiently through the circulatory system to all bodily tissues.
Unfortunately, the clinical signs of chronic renal failure usually do not show up until the kidneys are severely damaged. While chronic renal failure can be managed, it cannot be cured. Treatments are aimed at improving the cat’s quality of life.