Kidney Failure

Kidney failure is a common cause of illness in dogs and cats. Kidney failure can be lumped into two main categories: acute renal failure (ARF) and chronic renal failure (CRF). This article will explore ARF and CRF in depth including the causes, signs, diagnosis, prognosis, treatment, and preventative options. 

Before we can begin a discussion on renal failure, it is important to understand a little bit about what the kidneys do. Simply stated, the kidneys do two major things. First, they filter the blood, remove nitrogenous waste from the blood, and excrete the waste in the urine. Second, they control how much water is conserved or eliminated from the body. When kidneys fail, these functions cannot be carried out and the result is the accumulation of waste products in the body.

The signs of kidney failure can include: nausea, drooling, vomiting, lack of appetite, excessive thirst, excessive urination, weight loss, depression, weakness, sores or ulcerations in the mouth, and a change in the breath (uremic breath). Since there are different types and causes of kidney failure the signs can vary greatly from patient to patient. Most people assume that if an animal is urinating, the kidneys are working fine. However, the complete inability of an animal to make urine, or oliguria, is an uncommon sign of kidney failure and will usually only occur only in the late stages of the disease. 

Acute renal failure is the sudden loss of kidney function. It can occur at any age animal but is more frequent in younger animals. Things that can cause ARF to include certain toxins/chemicals such as antifreeze, certain medications such as some types of antibiotics and chemotherapy, heat stroke, a bacterial infection from Leptospirosis or selected other organisms, or prolonged anesthesia.

Chronic renal failure represents a more gradual process. CRF is most often the result of small, cumulative damage over a long period of time. Causes include genetically predisposed disease, diseases causing high blood calcium such as some types of cancer or hypoadrenocorticism, chronic obstruction within the urinary tract, and repeated doses of some types of medications over extended periods of time. Animals with CRF are often over age 7.

The diagnosis of kidney failure is relatively straightforward. Two kidney values, BUN (blood, urea, nitrogen) and Creatinine will be elevated in the blood of animals with ARF or CRF. Additionally, the urine-specific gravity, a measure of how well the kidneys are able to concentrate urine, will be decreased in animals with ARF or CRF. Additional tests are often needed to determine the exact cause of kidney failure. It is important to note that in cases of CRF it is often difficult to obtain an exact cause of the disease. In recent years, newer tests such as the ERD (early renal disease) and urine protein:creatinine (UP:UC) ratio are more readily available for the early detection and monitoring of kidney status.

The treatment of ARF and CRF is fundamentally similar. The mainstay of treatment is IV fluid therapy. Animals with ARF and CRF are most often admitted to the veterinary hospital for IV catheter placement and aggressive fluid administration. Fluids will help to flush out the kidneys and dilute the number of toxins that have built up in the body. Additionally, medications for nausea/vomiting, electrolyte imbalances, and bacterial infections, if present, are often administered.

In cases of CRF, if initial treatment is successful, other adjunctive treatments such as a special diet to decrease protein and salt intake, supplements that bind excessive phosphorus, and intermittent subcutaneous fluid administration may be implemented. Two newer supplements, Azodyl and Epakitin, have shown promise for animals with CRF.

Kidney transplantation for cats and dialysis for dogs and cats are available at a few veterinary colleges across the country. Transplant candidates must meet very specific criteria and can run over $10,000. In addition, the donor cat must be adopted by the family of the cat that is receiving the transplant. Dialysis is most often used for ARF versus for the frequent treatments that are required for pets with CRF. 

The prognosis for animals with renal failure varies greatly and is based on many individual circumstances. In general, pets that experience ARF and are diagnosed quickly and treated aggressively can survive and live a normal life. Delays in treatment can result in permanent damage and even death. For pets with CRF that are diagnosed in the early stages, a cure is often not possible but maintaining a comfortable quality of life is with appropriate treatment. For pets with CRF that are diagnosed in the late stages, management can be a challenge.

As with most things in life, prevention is easier than treatment. Kidney disease is no exception. Not all kidney diseases can be prevented. However, there are many things that can be done to minimize the amount of damage that is done to the kidneys over time and to identify problems early in the process. These include 1. Have an IV catheter placed and fluids administered any time your animal is under anesthesia. Small amounts of damage occur each time an animal is under anesthesia. IV fluid administration keeps the kidneys perfused and can minimize damage. 2. Keep your dog vaccinated for Leptospirosis, especially if your pet is at high risk. 3. Always administer medications according to the directions and under the supervision of a veterinarian. If your pet is on medications that can hurt the kidneys, have bloodwork done frequently to monitor for damage. 4. Have routine bloodwork and urine screens done if your pet is over age 7, has a heart murmur, or is at high risk for kidney disease. Again, finding kidney damage early is the key to successful treatment.

The information provided is for educational purposes only and is not intended to take the place of your regular veterinarian. Please do not hesitate to contact your regular veterinarian if you have questions regarding your pet.