Caring For Kitty's Kidneys

Got an aging cat? Better keep an eye on kitty's behavior. The litter box is only one of several places to look for signs of kidney disease.

Almost a third of cats over age 10 suffer from chronic kidney, or renal, disease. Long-haired cats and certain breeds may be more vulnerable, as they often have congenitally malformed kidneys. But kidney failure can be caused at any age by bacterial infection, injury, tumors, viral infection, or a protein buildup called amyloidosis. Chronic renal failure (CRF) is a leading cause of death in older cats; I lost my first cat to it when he was about age 11, and my 23-year-old little Vixen has been on a renal diet for years. What causes this, and what can you do about it? Let's explore.

Understanding Kidney Function
Most of us know that kidneys filter waste material from our bodies, but they do much more than that. Kidneys actually impact five bodily functions:

• Waste filtering
• Regulation of electrolytes
• Production of red blood cells
• Controlling blood pressure
• Producing urine

The kidneys are located on either side, not far below the backbone about midway down the cat's spine. They're, well naturally, kidney-shaped.

Inside the capsule of each kidney and organized into layers called the renal cortex and renal medulla are around 200,000 nephrons, which are tiny structures that act like filters. As kidneys become damaged, kidney cells are replaced with scar tissue. Once this happens, it is impossible for new kidney cells to be created. The kidneys react by producing a larger volume of urine with a lower concentration of toxins. A cat in this stage is said to have "compensated renal failure". Next, the kidneys begin producing less erythropoietin, a hormone that stimulates the bone marrow to produce red blood cells and hemoglobin, so anemia will set in.

In advanced kidney disease, the organs become small, hard and lumpy, their amount of functioning tissue greatly diminished. The symptoms described above will worsen. Only you will know when your cat's quality of life has become so low that it's time for euthanasia. For me, this came when he peed on me twice in the night, both times with no odor in the urine because no toxins were being removed. The next morning, his "third eyelid" began showing on the inner corners of his eyes. It seemed to me like he may have been in the early stages of dying anyway, and that made the decision a little less painful...but it was still excruciating to lose him.

What to Look For
If your cat's kidneys aren't functioning up to par, you'll notice several signs. Unfortunately, since cats are so good at masking illness, symptoms may not appear until about 70% of kidney function has already been lost. Kidney failure may further be masked by hyperthyroidism, which is common in older cats. Look for these telltale signs, although not all cats will exhibit all symptoms:

• Increased thirst - is kitty drinking a lot more water than usual? You may also notice him licking his lips more.
  
• Increased urination - all that water has to go somewhere!
• Loss of appetite - because toxins are building up in the cat's body, it makes him feel sick to eat.
• Vomiting - you may see vomit unrelated to hairballs, shortly after the cat eats. It may appear clear and foamy or contain large amounts of food.
  
• Weight loss - this stands to reason, if the cat's not eating as much or keeping food down.
• Poor coat quality - don't dismiss this as merely a sign of aging. Loss of potassium in all that extra urine can make the coat appear dull.
  
• Lethargy - yes, cats sleep a lot, but a cat with renal failure will be even more listless. She may even seem depressed, showing little interest in playing or interacting with you.
  
• Weakness and balance problems - obviously, if your body is filled with toxins, you're losing all your potassium, you're anemic, your muscles are wasting away, and you can't keep your food down, you're going to be weak and wobbly!
• Breath and body odor - as toxins build up in the cat's body, you may notice an odor. Since cats don't have a body odor like dogs do, if you can smell your cat, there's an underlying problem. Fishy breath from bad teeth may start to smell more like ammonia, as well.
• Mouth sores - ulcers inside the mouth or on the chin may erupt.
  
• Pain - your cat may seem sore when you try to touch her middle back area, or sit in a hunched-up crouching position that looks like she's in pain.
• Heightened sensitivity to sound - kitty may be more easily startled or seek out quieter places to rest.
• Changes in litter box behavior - aside from the more frequent urination, some cats get diarrhea, while others get constipated. Some even start eating cat litter!
  
• Blindness - in rare cases, some cats will suddenly go blind from kidney failure. This can be caused by detached retinas resulting from high blood pressure.
  

Any one of these by itself may not be unusual, but if you see two or more, it's time to visit the vet. End-stage symptoms could include convulsions, lowered body temperature, and coma. It goes without saying that catching renal failure early can make all the difference.

Some cats have a higher predisposition to renal failure than others. These include the Maine Coon, Abyssinian, Siamese, Russian Blue, Burmese, and Balinese breeds. Older cats are also more prone to it, while the cat's diet and environmental factors can also play a factor.

CRF: Not The End!
While chronic renal failure is a progressive disease that's always terminal, your cat can live for years beyond initial diagnosis. It will require good management on your part, and kitty won't necessarily like all the treatments. But quality of life will still be pretty good until the very end, so it's worth the effort.

The earlier the diagnosis with CRF, the better the prognosis. If your cat's over about age 7, it's a good idea to have your vet run a series of annual kidney function tests on him or her. One blood test will check the Blood Urea Nitrogen (BUN); normal readings should be 60-80 mg/dl. When it's double that, kidney damage is evident. A second will check for an elevated level of creatinine, while a urinalysis checks the urine's specific gravity (USpG). A USpG reading below 1.030 could indicate that at least 2/3 of the kidney tissue is damaged. Your vet may also want to measure the blood levels of elements like potassium, phosphorus and calcium, as well as the counts of red and white blood cells to determine how far any disease may have progressed.

Once diagnosed, treatments vary depending on the causes of the CRF and how far it has progressed. Water intake should be encouraged with additional bowls, pet fountains, or adding extra water to the cat's food. There are drugs to help with the anemia symptom by stimulating bone marrow production, while phosphate binders can help prevent further kidney damage. Some say that restricting the amount of protein in the cat's diet, mainly for the phosphorus in it, is important, but others disagree and say a higher-protein diet is best. Your vet will likely put kitty on a diet of prescription cat food, often referred to as a "renal diet". Some cats do well on this, while others refuse to eat it; if yours won't, it's much more important to feed him something that will help maintain weight and good body condition. Weight loss is the enemy, and high moisture content is more important than protein content. Potassium supplements may also be necessary and both Omega-3 fatty acids and antioxidants have proven helpful. Supplements of vitamins B and C should be given daily. Some cats will show an improved appetite when given anti-emetics to combat their nausea. Others may need drugs to lower their blood pressure, as hypertension can be a result of poor kidney function.

In more advanced progression, you may also need to give your cat subcutaneous fluids daily to prevent dehydration. It's impossible for the cat to drink enough water to meet the demands of her compromised kidneys. Fluids will help flush toxins from her system and make her feel much better. The fluids are administered by pinching up a section of skin and inserting a needle into it, then keeping the cat still while saline solution drips from an IV bag for about five minutes. Afterward, she'll feel "sloshy" underneath the chest, as the fluids will gather there and be absorbed by her body as needed.

While none of these treatments will prevent eventual kidney failure, they can help your cat continue to live comfortably for months or even years beyond initial diagnosis. Consistency and vigilance are critical.

Worth a Pound of Cure
Obviously, preventing kidney failure in your cat is the preferable route. Several steps can be taken to promote kidney function, or avoid doing damage to the kidneys. They include:

• Keep kitty's teeth clean - bacteria and toxins from gingivitis damage not only the kidneys, but other major organs of the body, as well. Daily brushing, if your cat will tolerate it, and regular dental scalings at your vet can help avoid this.
  
• Feed plenty of wet food - an all-dry-food diet is contrary to a cat's natural bodily functioning, which is to get most or all of their water from consuming prey. Dry food only provides half the water of canned or homemade wet food and leads to chronic dehydration, even when plenty of water is available. This stresses the kidneys and lower urinary tract by forcing a high degree of urine concentration.
• Avoid toxins - this goes far beyond keeping kitty indoors to limit exposure to lawn chemicals and antifreeze. Many of the products we use in the home can be extremely toxic to cats. These include various types of cleaners, ant traps, rat poison, new rugs (due to the formaldehyde fumes coming off the backings), house plants, flame retardants, and art project fixative sprays.
  
• Forgo annual booster shots for feline distemper - any beyond the first vaccination for feline distemper are unnecessary, and may be linked to immune-mediated inflammation of the kidneys.
• Get annual kidney tests on cats over age 7 - the earlier kidney failure is detected, the longer your cat can maintain a good quality of life.

While there are no guarantees and not every disease is preventable, by keeping your cat safe and healthy you can help ensure many joyous years with a cat who has well functioning kidneys.

Purrs!

Many thanks to the Feline CRF site, All About Cats, and the Feline Advisory Bureau, all listed on OldMaidCatLady.com's links page, along with numerous other omnibus Q-and-A sites, for information contributing to this post.