Pet Kidney Failure
Disease is Common Health Problem for Cats
Jennifer Hawkins, DVM
If someone tells me their pet has kidney problems, I immediately assume that we’re talking about a senior aged cat. Why? Senior cats nearly always acquire kidney disease as they age and this is a frequent feline topic in the veterinary exam room. While it can occur in dogs, it happens to nearly all cats fortunate enough to live otherwise long, healthy lives.
What is Kidney Failure?
Medically speaking, the terms kidney insufficiency and kidney failure have different meanings, however, they are often used interchangeably. The word “renal” refers to the kidney and, because cats are so good at masking signs of illness, often pet owners don't recognize any symptoms until about 2/3 of kidney function is lost. The process of diminished kidney function occurs over time and, while kidney failure can occur acutely (over a short time frame), acute kidney failure is not common. For the purposes of this article I will be discussing chronic renal failure (CRF).
What Do the Kidneys Do?
The kidneys perform many important jobs.
- Maintain hydration. When an animal is not taking in much water, the kidneys conserve water by reabsorbing it as needed. Cats with CRF produce large volumes of dilute urine.
- Produce a hormone to stimulate production of red blood cells. When kidney function is diminishing, one of the signs noted on lab work is a decrease in red blood cell concentration (anemia).
- Blood pressure regulation. A collection of hormones and chemicals received and produced by the kidneys helps maintain a normal blood pressure. In animals with diminished kidney function, often there is an elevation in blood pressure.
- Electrolyte balance. Cats with poor kidney function often have to take medications to balance potassium and phosphorus, but other electrolytes are also affected.
- Excretion of metabolic waste products such as urea. As the body breaks down food products, like protein, into smaller pieces that are absorbed and transported to tissues and cells, waste products are passed through the kidneys. When the kidneys aren't properly doing their job, these wastes tend to build up in the blood, making animals feel lethargic. One of the main waste products we are able to measure in the blood is called urea. We tend to assume that if this waste product is high, so are others that we cannot easily measure.
Symptoms of Decreased Kidney Function
Increased thirst and urination are the most common signs of renal failure.
As the kidneys are failing to conserve water, more is lost into the urine. The body recognizes that it is not conserving water and is getting dehydrated, so thirst is stimulated and animals drink a lot more water to try and maintain hydration.
However, this is a losing race as the ability to drink water is exceeded by the amount of water lost through the failing kidneys into the urine. Often, pet owners are surprised to learn that their cat is dehydrated because they know it drinks lots of water. Yes, but they just can't keep up with their own losses.
Vomiting is another symptom of renal failure. As toxins build up in the body, acids in the stomach also build up which can lead stomach irritation and vomiting.
High blood pressure is tough to recognize at home, but sometimes the retinas can detach due to high blood pressure leading to acute blindness. Also, hypertensive cats will sometimes vocalize more.
Other signs are weight loss, weakness, poor appetite and ulcers in the mouth.
What Causes Kidney Failure?
While some cats are born with abnormal kidneys, most cats develop chronic renal failure merely as they age over a period of time.
How is Kidney Failure Diagnosed?
Early stages of kidney disease or kidney insufficiency can often be discovered with routine wellness blood work on your cat's annual exam. If found early on, your veterinarian can monitor lab values regularly or change your cat's diet to a kidney-friendly food. Later stages of kidney disease or failure typically are diagnosed when an owner becomes aware of symptoms that prompt the veterinarian to perform diagnostic blood and urine tests.
How is Kidney Failure Treated?
Early treatment for kidney failure may include monitoring of lab parameters or placement on a low protein diet.
Less protein ingested helps decrease the amount of blood urea that builds up and thus helps delay the progression of illness. As the disease progresses, saline administered under the skin (subcutaneous fluids) on a regular basis can help combat the chronic dehydration caused by the failing kidneys.
Other treatments may include blood pressure medication, anti-nausea and antacid medications, medications to regulate electrolytes and even hormone injections to promote red blood cell production in cats anemic from kidney failure.
If a cat is sufficiently ill, hospitalization and placement on intravenous fluid therapy may be needed to bring down toxins in the bloodstream and restore hydration sufficiently to be maintained on treatment at home.
What's the Prognosis of Kidney Failure?
While there is no cure for kidney failure, kidney transplants and dialysis are available in some areas. For most cats — for which these more aggressive treatments are not an option — symptomatic care can often provide good life quality for two years or more, depending of the severity of the disease process at diagnosis.
Dr. Hawkins received her veterinary degree from the University of California, Davis and practices in Orange County, Calif., where she also works at local animal shelters. In addition, she is an advisory faculty member for aspiring veterinary technologists at California State Polytechnic University Pomona. Dr. Hawkins is an active member of the Southern California Veterinary Medical Association where she serves as president on the Board of Trustees.