Kidney disease is, unfortunately, the number one cause of death in older cats and dogs. Kidney disease is common and treatment options are limited.
Every cell in the body has to take in nourishment to live and function, and like every other organism on the planet , has to excrete waste products. Most of these cellular waste products are excreted into the extracullar fluid and are then absorbed by the capillary beds into the veins. The blood in the veins is directed back to the heart, then the lungs, back to the heart freshly oxygenated, and then to the rest of the body with a large percentage going through the kidneys which act like a super sophisticated filter that removes toxins, medications, urea, creatinine, and other cellular waste products from the blood. This is critical to life.
But the kidney does much more than just filter, recycle, and excrete metabolic waste products.
Kidneys also regulate how much fluid is retained in the body by keeping sodium, potassium, and other chemical salts in balance.
The kidneys detect oxygen deprivation and produce hormones that signal the bone marrow to produce more red blood cells (erythropoietin) and angiotensin that regulate blood pressure. Kidneys don't function well if the blood pressure isn't in a healthy range.
A lot of the waste products from cellular metabolism are either acidic or alkaline (basic) in nature. And our diets are sometimes excessively acidic or alkaline. All these acids and bases need to be kept in balance or illness and cellular death occurs. The kidneys play a major role in acid-base regulation.
But so much can go wrong.
The causes of kidney disease include:
Infection: bacteria anywhere in the body is eventually expelled from the body from either the bowels, the mouth, or through the kidneys. So, the kidneys are exposed to a lot of bacteria, and the kidney tubules are very delicate,small, and susceptible... and the result of an infection is inflammation and scarring rendering the tubules useless. At least with bacterial infections we have a chance to cure with antibiotics.
Poisons & Toxins: Antifreeze is the most common toxin we associate with kidney disease in veterinary medicine, but there are those that argue that cleaning chemicals and pesticides and lawn fertilizer all end up on paws that then get licked and ingested; all of which ends up harming ... to some degree ... the liver and/or kidney. There are those who suspect food preservatives and dyes and artificial coloring agents and so forth as possible culprits. Maybe they're right.
Endo Toxins: Perhaps the most common source of damaging toxins to the kidneys, though, comes from our own bodies: Everytime our immune system does battle with germs and pollens and whenever we have poor digestion or become dehydrated or our cells become poorly oxygenated, there are aldehydes, ketones, lactic acid, oxidative free radicals, and the waste products of inflammation produced that have to be eliminated. All of these are potentially damaging to the kidneys. All that old advice about keeping active, keeping fit, and drinking lots of fluids really is critical to good health.
Cancer: In my experience, cancer of the actual kidneys is pretty rare. But on the other hand, cancer elsewhere in the body is common in older cats and dogs and anything like cancer that affects the immune system and circulatory system is likely to adversely affect the kidneys too.
Auto Immune Disease: The professors tell us that the most common cause of kidney failure is that the kidney tubules fill up with amyloid, which is a type of scar tissue rendering the kidney non-functional. And the reason the tubules fill up with amyloid is because the body's immune system doesn't recognize the kidney tissue as healthy and vibrant but rather as damaged. So just like a flesh wound, the immune system starts up the biological machinery to "repair" the damaged tissue by filling it up with scar tissue. You only need about 25% of your kidney to be healthy to function normally ... which is why you can safely donate a kidney to your sister if need be ... but at some point the kidney doesn't have enough functional tubules left to keep up with all the waste products and urea that need to be eliminated, so they build up to toxic levels in the blood stream making the patient very sick, weak, and nauseated.
Of course, the amyloid-auto immune attack on the kidney is probably triggered because of cell damage caused by the other stuff on this list: toxins, poor circulation, infections, and so forth.
Poor Circulation: This is another big factor in kidney health. Like the brain, the kidneys are very sensitive to changes in blood pressure, blood flow, and oxygen saturation. That's why heart disease and kidney disease so often go together. Any disease that affects circulation or the red blood cells such as diabetes, spleen cancers, bone marrow diseases, vascular diseases, and anemia's all can be brutal to the kidneys. Patients often die of kidney disease before they succumb to the underlying disease. Note: one of the extra duties of the kidneys is producing a hormone or chemical called erythropoietin that's needed to stimulate the bone marrow into producing more red blood cells. So you can see; it can become a vicious cycle: the diseased kidney doesn't do it's job of producing the hormone needed to start up red blood cell production ... which leads to anemia ... which makes the kidney even sicker.
Wear & Tear & Oxidation: This is a non-scientific category: just getting old. The kidney is a type of filter and chemical pump and just like any such mechanical device can wear out, get clogged up with crud, and rust. Cells oxidize and deteriorate. Tissues become unable to survive all the assaults of toxins, chemicals, and waste products like they could when they were younger. Maybe it's in the genetic code; tissues stop regenerating well after a certain life span.
Stones, Mechanical Damage, and poor Out Flow: We don't really know why kidney stones form in some patients and not in others, but we do know that diet is a factor. Regardless, sometimes kidney disease is caused by the mechanical irritation and inflammation caused by having stones rolling around in the kidney. But the big problem is more likely caused by the build up in pressure whenever there's an obstruction anywhere down stream of the kidneys preventing the out flow of urine. This can be caused by stones clogging up the cortex of the kidneys, the ureters (tubes carrying urine from the kidneys to the bladder) or infection, inflammation, or stones in the bladder or urethra. Note: this is why we like to test for kidney damage when your pet has a lower urinary tract problem. The system is CONNECTED or INTER RELATED. The foot bone is connected to the ankle bone ...
I digress. Let's get to the main point of this page:
What To Expect From Your Vet If Your Pet Has Kidney Disease:
(Of course, your vet may do things differently)
History: Understand that symptoms range from NONE to almost dead. The classic signs that make us very suspicious of kidney disease, though, are: excessive drinking and urination, weight loss, muscle loss, lack of appetite, loss of mental acuity, and very dilute or water like urine. As routine blood testing of senior pets becomes more common, we're often able to detect the early and mid stages of kidney disease before any overt symptoms appear. Our most typical case, though, is a report from the owner that their older pet isn't eating much and just isn't feeling well.
Exam: As usual, we examine your pet from head to toe. If your pet has kidney disease advanced enough to have symptoms, here's a list of things we'll be looking for:
General poor vitality; this is a subjective finding based on gum color, brightness to the eyes, poor hair coat and grooming, mouth odor, and posture.
Weight and muscle loss. Especially loss of cheek muscles making the cheek bones prominent and loss of muscle mass along the spine. This is because kidney disease involves the loss of protein through the urine.
Signs of disorientation and nervous twitches of the facial muscles.
Mouth or tongue ulcers. Wounds that won't heal.
Signs of anemia and a weak femoral pulse. Dehydration is common too.
And once again, we look for additional problems; one sick organ system often affects another. It's common for kidney patients to also have circulation problems, heart problems, and liver and gastro intestinal disease all at the same time.
Blood Work and Urine tests: The classic blood tests for kidney disease are high BUN, high Creatinine, the ratio between these two, low blood albumin in chronic cases, and high phosphorous counts. High urine albumin, and dilute urine specific gravity are classic urinary findings for kidney disease. All of these tests are fairly inexpensive and routine and are usually done as a diagnostic panel for sick patients.
Radiographs: Radiographs tell us several important pieces of information: Are the kidneys normal in size, shape, consistency, and are there stones or tumors present? By consistency, I'm referring mostly to cysts: one form of kidney disease called cystic nephritis shows up well on radiographs.
Ultra Sound and other forms of imaging: If your veterinarian has MRI, CAT Scan, or Ultra Sound available, they can be used to make a diagnosis that might otherwise be missed.
Biopsy: I've never done a kidney biopsy on a live patient, but some vets are skilled at getting biopsy samples, and if so, then the results would tell us whether the kidneys were cancerous, infected, cystic, filled with amyloid etc.
Hospitalization and Critical Care: A lot of kidney disease patients come into the clinic because they've been sick and not eating for several days or more. They are so sick, in fact, that they need IV Fluids, injectable medications for nausea, oxygen therapy, and supportive care.
Antibiotics: May or may not be used depending on whether or not infection is suspected. Even if there is no evidence of infection, a lot of vets will still recommend antibiotics as a preventive measure. Damaged tissue is very prone to infection and sick and weak patients are prone to secondary pneumonia and other infections.
Steroids: Once again, frequently used by many vets for their benefits (reduced inflammation, control over auto-immune disease, increase water intake and flushing, and appetite stimulant) but controversial because of the potential negative side effects.
Non-steroidal anti-inflammatories and pain medications: Atopica, cox-1 inhibiting pain medications, valium, and other similar medications are often used to make the patient feel better. But we have to be extra cautious because so many medications require a healthy kidney for excretion, and if the kidneys aren't functioning well, then the medication may quickly rise to toxic levels and do more harm than good.
Diet is the most important part of kidney therapy.
Anti-Oxidants, Omega Fatty Acids, and other Supplements:
Durlactin Feline: Durlactin is a wonderful combination of omega fatty acids and anti-inflammatory agents that is very safe and seems to help a lot of sick cats feel better. it's official use is for arthritis pain and inflammation.
Durlactin Canine: Also helpful but lacking the omega fatty acids that aid in micro blood circulation to the kidney.
Azodyl: This formula of naturally-occurring beneficial bacteria metabolize and flush out uremic toxins that have diffused into the bowel. This slows down uremic toxin buildup in the blood and helps prevent further kidney damage.
This product is for both dogs and cats.
Epakitin: This is the first phosphate binder that cats will eat willingly. Getting rid of the build up of phosphates in the blood associated with kidney disease is very helpful. High levels of phosphates in the blood really make you feel terrible. There are several other medications sold at human pharmacies that bind phosphates that are less expensive but they are very bitter tablets and often cause GI upset... very hard to give to cats especially. Epakitin is made from ground up crab shells and is quite palatable to most cats.
Epakitin lowers urea concentrations, but its strength lies in its ability to reduce serum phosphorous levels.
Anti Oxidants: These are sold as neutroceuticals which frightens those of us who believe in "evidence based medicine", but nonetheless, such products may very well help prevent or slow down cell death associated with free radical damage prominent in kidney disease.
Secondary Medications: I'm referring to anything needed to treat with secondary symptoms such as medications used to stimulate appetite, aid in digestion, or suppress nausea.
Dialysis and Kidney Transplantation: Not generally available for pets.
Referral: Not all general practices are set up for aggressive work ups and treatment of terminal patients. Consider referral.
Euthanasia: I mention this to prepare you. Sadly, a large majority of patients in the later stages of kidney disease are so miserable that we encourage compassionate euthanasia. I'm very sorry.