Veterinary Help

Chronic kidney (renal) failure is common in middle aged to older dogs and cats. It refers to primary kidney disease that has been ongoing for months to years. There are various underlying causes but the effect is irreversible damage to the kidneys though the condition may be managed by addressing underlying secondary problems.

Causes may be congenital or inherited and thus typically suspected when seen in younger animals, or acquired as is most common in older animals. Acquired chronic kidney failure results from any process that damages any component of the kidneys. The initiating factor is often unknown but inflammation is frequently present.

Clinical signs may be insidious in onset and not noted immediately. This includes slow weight loss, increased drinking and urination and loss of appetite. There may also be intermittent vomiting. If these signs are subtle or missed, the patient may present as if the process is acute (sudden onset of not eating, persistent vomiting and lethargy) even though the underlying disease has been present for some time. Other clinical signs include ulcers in the oral cavity, depressed mentation, seizures or blindness.

Initial diagnostics that indicate kidney failure are blood work that shows an elevation in the kidney values (BUN – blood urea nitrogen and creatinine which are typically cleared by normally functioning kidneys) along with a decreased ability to concentrate the urine. Other changes with chronic renal failure may include an increase in phosphorus, low potassium, elevated calcium. These changes result from the kidneys impaired ability to filter or retain these minerals as is normally done. The red blood cell count is also typically decreased as the kidneys are not able to produce normal amounts of erythropoietin – the hormone responsible for telling the bone marrow to produce red blood cells.

Since the damage to the kidneys is irreversible, the goal of therapy is to correct underlying dehydration, electrolyte imbalances, clear buildup of toxins and address any current disease processes that may further injure the kidneys. The additional diagnostics include a urine culture to help determine if a urinary tract infection is present and if so identify the bacteria to find the most effective antibiotic for treatment. X-rays of the abdomen will help identify kidney, ureteral or urinary bladder stones which can predispose to infection or further damage. They can also identify abnormalities in size or shape of the kidneys. Changes here can indicate a cyst or tumor. An abdominal ultrasound can evaluate the architecture of the kidneys. This allows better visualization of any cysts or tumors that may be present as well as any abnormal dilation of the kidneys. Blood pressure readings are indicated as hypertension is often seen with kidney failure and if untreated not only contributes to the patient not feeling well but can hasten kidney damage.

Treatment includes intravenous fluids if the patient is dehydrated, vomiting or not eating. This helps restore fluid and electrolyte balance. These patients are treated symptomatically for vomiting with medications to stem the vomiting and protect the gastrointestinal tract. Antibiotics are used if indicated. Hypertension is addressed with medication when it is present. Once the patient is eating and hydrated, long term oral medications can be instituted. These include a diet change to a prescription diet that has appropriate amounts of high quality protein as well as ideal concentrations of minerals and electrolytes. Patients may be placed on phosphorus binders to help keep phosphorus levels from rising and a potassium supplement if indicated. In cases of severe anemia, recombinant human erythropoietin is the treatment of choice though not without risk. It can cause seizures, allergic reactions and refractory anemia due to the animals immune system attacking the erythropoietin. At home, smaller dogs and cats an benefit from regular subcutaneous fluid therapy to help with hydration.

Chronic kidney failure patients can in some cases have a good quality of life for many months with good management, particularly if the disease process is caught in the early stages. This is one of the reasons it is important to regularly check screening blood work and urine samples on older pets.