Introduction
Chronic renal failure (CRF) in dogs 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 “failure”. Unfortunately, once prolonged clinical signs appear, the kidneys normally have lost most of the ability to perform their normal functions of filtering the blood, excreting the end-products of body metabolism in the urine and regulating the concentrations of hydrogen, sodium, potassium, phosphate and other electrolytes in the animal’s bodily fluids.
Symptoms of CRF in Dogs
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 body. 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. However, they almost always do accompany the disease. Other signs that owners commonly notice are anorexia/inappetance, weight loss, vomiting, lethargy, halitosis (bad breath), seizures, bleeding/clotting problems, and altered states of consciousness. In severe cases, affected dogs may develop high blood pressure (called 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 already severely damaged by long-term injury. While chronic renal failure can be managed, it cannot be cured. Treatments are aimed at improving the dog’s quality of life.