Dealing with Kidney Disease in Pets

With proper care, diagnosis, and treatment, you can keep dogs’ and cats’ kidneys in fighting shape

You can hear your pet’s heart beating when you put your ear to his chest. You can see his lungs working when he gulps air during play. But the function of his kidneys is less apparent, although no less vital.

Your pet’s two kidneys are found next to each other near the backbone and just behind the liver inside of the abdomen. One of their main roles is to filter substances—such as drugs, toxins, and waste products from metabolized food—from the bloodstream and eliminate them in urine. The kidneys also keep your pet properly hydrated by concentrating urine to conserve water or diluting it to excrete water, depending on how much water your pet has drunk.

The phrase kidney disease describes the process leading to acute or chronic kidney failure. When the kidneys fail, they shut down and cannot do their jobs. This leads to urine with an unchanging concentration, which causes dehydration despite the pet’s water intake. Kidney failure also causes a buildup of waste products, which can make your pet sick. About 70% of kidney capacity must be lost ­before signs of kidney failure arise.

Acute kidney disease can occur suddenly at any age and can range from mild to severe and may be reversible. Chronic kidney disease is progressive and irreversible. During the early stages of chronic kidney disease, you may not notice any symptoms in your pet. As the chronic disease progresses over time, your pet may show signs such as excessive thirst and an increased volume of urine.

What causes kidney disease?
Chronic kidney disease is relatively common in older pets, especially cats. About 30% of cats more than 10 years old have some degree of kidney disease, and 49% of cats older than 15 have chronic kidney failure.

Chronic kidney disease also is found in puppies whose kidneys do not form normally after birth (congenital kidney dysplasia). Certain dog breeds are predisposed to this, or it simply may occur spontaneously. Persian and other long-haired cats are predisposed to polycystic kidney disease, where the kidneys develop abnormal cysts that progressively replace the normal kidney structure.

When kidney damage causes protein to leak from the blood into the urine, the condition is called protein-losing nephropathy. This syndrome can present as kidney disease that’s acute or chronic. Frequently, it is due to other problems, such as infections (for example, Lyme disease and certain types of ehrlichiosis), immune disorders (such as lupus), or cancer, but it may be due to inherited kidney problems in certain breeds.

Acute kidney failure in dogs is linked to ingestion of toxins such as antifreeze, ibuprofen, grapes, and raisins.

Acute kidney failure in dogs is linked to ingestion of certain toxins such as automotive antifreeze, ibuprofen and other nonsteroidal anti-inflammatory drugs (NSAIDs), grapes, and raisins. Also, infections such as leptospirosis and bacterial bladder infections that go upstream to the kidneys can cause damage. In cats, common toxins include ingestion of parts of a lily plant and NSAIDs, as well as pyelonephritis (kidney infection caused mostly from infections that start in the bladder) and obstructions of the ureters (the tubes that drain each kidney to the bladder) from stones or debris. Additionally, anything that decreases blood flow to the kidneys, such as low blood pressure—especially from prolonged dehydration or anesthesia—can cause acute kidney failure in dogs and cats.

If your pet is diagnosed with kidney disease, the veterinarian can tell you which stage of the disease your cat or dog is in. Stage I is when abnormalities of the kidneys are present but kidney function remains normal. In Stage II, mild kidney dysfunction is noted. Stage III is moderate dysfunction. Stage IV is a severe form of the disease. Recommendations for further testing, monitoring, and treatment are based in part on which stage of the disease the veterinarian determines for your pet.

How can I try to prevent kidney failure?
Keep a watchful eye on changes in your pet’s behavior, appetite, and weight. Bring in your pet for annual checkups. Your veterinarian will perform a blood test and a urinalysis to help detect early kidney disease.

Feed your pet a well-rounded diet, but bear in mind that in some cases, certain diets and treats will predispose your dog or cat to kidney stones. Therefore, it’s important to speak with your veterinarian about which diet is best for your pet. Also be sure to allow your pet ample access to fresh water, and keep your cat or dog fit and in an appropriate weight range. Finally, keep toxins such as those noted earlier out of your pet’s reach.

How is kidney disease treated?
Fluid therapy is the most important treatment in most cases and usually is given intravenously. The decision to hospitalize for fluid treatment and other therapy depends on how sick the pet is, its level of dehydration, and whether it can tolerate oral medications. Once a pet is stable enough to go home, your veterinarian may teach you to inject fluids under your pet’s skin daily or every other day. While the thought of this might sound frightening, fluid injections are not difficult to complete.

Many pets will need medications (for example, antacids, drugs to prevent vomiting and nausea, or ulcer treatments) to control gastrointestinal problems associated with kidney disease. If kidney disease is caused by an infection, your veterinarian will prescribe antibiotics. High blood pressure, which is common with kidney disease, also may be treated with drugs.

With acute kidney failure, the kidneys may be unable to make enough urine to eliminate the pet’s fluid, and water overload can occur. Diuretics may increase the urine volume, although the kidneys may be too damaged to respond. In that situation, dialysis may stabilize the patient. In pets with obstructions like kidney stones, the ureters may need to be unblocked surgically or a stent placed between the kidney and the bladder to allow urine to drain.

For chronic kidney disease, one of the most effective treatments is a special diet that your veterinarian can outline for you. Such diets slow the progression of damage and increase survival time. A feeding tube, which generally is well tolerated, can be placed in some patients. Kidney diets are designed to keep your pet’s blood phosphate concentration normal. If the phosphate level is at or above the high end of the normal range, even with the special diet, medication can help.

Chronic kidney disease may progress rapidly in some, while others may live for years before being impacted.

Protein in the urine can be treated with inhibitors to decrease blood pressure in hypertensive patients, but many times another drug may be needed.

Kidney transplants are an option for cats that don’t respond to other treatments and don’t have disease that has advanced too far. A transplant is considered only when kidney function is no longer adequate to maintain a good quality of life. To date, kidney transplants are not usually performed in dogs because rejection rates are higher and donor programs are less accessible.

What is the usual outcome of treatment?
Unfortunately, about half of pets with acute kidney disease will not recover. Of the pets that do, about half of them will have lasting kidney damage, but many of those can be managed with diet and medications.

For pets with chronic kidney disease, there is wide variation in outcomes. The disease may progress rapidly in some, while other pets may live for years before their quality of life is impacted. Cats and dogs with early kidney disease can live an average of two to three years; those with moderate disease, about two years; and those with severe disease may succumb within a few months. In many cases, pets with chronic kidney disease can lead relatively normal lives, as long as their disease is monitored and treatment is adjusted accordingly.

How do I know if my pet has kidney disease?

These are some classic signs every pet owner should watch for. If you notice any of the symptoms below in your dog or cat, contact your veterinarian to schedule an appointment to have your pet examined. 

• Excessive thirst
• Increased urine volume
• Changes in appetite, such as refusal to eat the standard food, taking longer to finish a meal, eating a smaller quantity, or not eating at all
• Weight loss
• Nausea or vomiting