cat-pet-animal-domestic-1048272161 North Bend Rd Ste C
Hebron, KY41048
(859) 431-2287
Lauren Dell, DVM

If we have just diagnosed your cat with Chronic Renal Failure (CRF), we have just given you some scary news mixed with a dizzying array of numbers and statistics. This worksheet is designed to help you understand the tests we will perform, the treatments we offer now and long-term, and what to watch for and expect down the road.

The kidney is a complex body part that plays several roles: removing wastes, balancing salts and minerals, and regulating blood pressure and red blood cell production. The word “renal” refers to kidney. Like us, cats have 2 kidneys. Each one is made up of thousands of units called nephrons that work individually to filter the blood. As a pet ages, nephrons wear out. Further damage can be done by infections, toxins, kidney stones, or illness. As nephrons wear out, the kidney becomes less efficient. Many pets don’t act sick until there is only 20 % of the original kidney function. The most common signs of CRF are increased thirst and urination. Imagine a leaky toilet that uses more and more water to get the job done. As kidney disease advances, we usually see loss of appetite, weight loss, and vomiting.

The Tests

Urinalysis- Testing a urine sample gives valuable information about the kidney. As function declines, the sample becomes more dilute. The Urine Specific Gravity is measured from 1.000 to 1.045 and while most young cats produce a sample at 1.045 or stronger, the cat in CRF will usually give a sample of 1.010- 1.020. We also look for infection, protein, casts (like scabs from the kidney), or crystals. These findings may indicate a treatable disease. Pets in CRF may not show the typical straining and frequent urination of an infection, so we repeat urine samples every 6 months or if they are ill.

Blood tests:

SDMA: This groundbreaking test is available exclusively through our lab and detects declining kidney function with as little as 40% kidney loss. Early detection allows us to intervene much sooner and preserve the remaining kidney function.

Azotemia vs. uremia: The Blood Urea Nitrogen (BUN) and Creatinine are waste products from the metabolism of protein. These values climb as renal failure worsens. Dehydration also makes them rise. The BUN also increases with bleeding in the digestive tract. Uremia is a condition in which the high BUN and Creatinine are making the pet feel sick.

Ca and Phosphorous: the balance of the bone-building minerals is regulated by the kidney and can rise in CRF, causing nausea and weak bones. Special diets usually control this problem, but antacids or other medication may be needed.

Potassium: this critical salt is lost in CRF and low potassium in turn causes further kidney damage, so it is added to renal diets. It can be also be increased with oral supplements and added to intravenous and SQ fluids. Patients with low potassium have muscle weakness.

Blood pressure: many patients with CRF develop high blood pressure, which further damages the kidneys.

Ultrasound +/- biopsies: Some patients may have signs or lab results that suggest an active, progressive disease rather than the simple wear and tear of old age. In these cases, we may suggest ultrasound examination and possibly biopsy to diagnosis the condition.

Staging Kidney Disease

IRIS (International Renal Interest Society) staging allows us to target which treatments are indicated for your cat.

Stage 1: These cats look and act normal and the majority of their tests look normal, but they have increased SDMA, more dilute urine, and may have protein in the urine or abnormal size and shape to the kidney. We screen these patients for other treatable problems like infection and high blood pressure and avoid medications that may damage the kidneys. Labs are typically rechecked every 6 months.
Stage 2: These cats may show mild changes in thirst and urination, some weight loss, and mild changes on lab results. At this stage we start feeding renal diets.
Stage 3: These cats have more severe lab changes and show more weight loss, nausea, and loss of appetite. In addition to renal diets, some of these cats receive routine fluid treatments. See SQ fluids below. Labs are checked every 3 months.
Stage 4: These cats have advanced kidney disease and may have more severe complications such as anemia and gastrointestinal ulcers.


 Gastroprotection and antinausea: CRF patients are prone to stomach and small intestinal ulcers and may have nausea due to high phosphorus or uremia. Medication that decreases stomach acid such as famotidine (Pepcid) and omeprazole (Prevacid) can help. Some phosphate-binders also help, for example, Maalox.


 IV and SQ fluid dialysis: As a point of clarification, we should note that humans with CRF usually retain water and go to dialysis to have it removed. Cats loose water faster than they can drink and become dehydrated. When pets become too ill to eat and are vomiting, we typically hospitalize them for 3-4 days of IV fluid given at twice the normal rate to flush them out. At home, SQ fluids given every 2-7 days provide a mini-treatment. After a few treatments, it is usually very obvious to the owner when the pet needs another treatment.

A few pointers for SQ fluids:
 Store fluids in a clean place with a fresh needle or clean cap on the end.
 Use fluids for 1 month after opening, then discard bag.
 Use a new needle for each session. Needle can be reused if placing fluids on left and right sides during one session.
 Fluids can be warmed with a heating pad or baby wipe warmer. Do not microwave-the tubing will melt.
 Unfold a paper clip to form an “S” or use a wire hanger to make an easy hook to hang bag on a cabinet door or from a plant hook.
 Tuck your pet’s head under your elbow and hold the rest of the body with your forearm like a football. Alternatively, place your pet in open-topped box that is just big enough, like a shoebox.
 Note how quickly the fluids are absorbed. If they are absorbed within a few minutes, the pet needs a larger volume and/or more frequent treatment. If they are still present 6 hours later, decrease the volume.


 Diet: This is the most important tool for controlling CRF and providing for quality of life. Since your pet is not feeling well, it may take careful introduction and several trials to find the best food. We stock 3 brands of canned and dry foods. Slowly transition from the old diet over 5-10 days. Offer small amounts of warmed canned food frequently and avoid leaving stale canned food near a sick cat. Appetite stimulants can help. As a last resort, we can provide recipes for home cooking. Patients who successfully transition to renal diets typically enjoy 2-3 times survival times with improved strength, weight, energy, and less vomiting. (P.S. Over-the-counter “urinary health diets” are NOT KIDNEY DIETS and are worse than regular cat food for CRF cats.)


 Monitor weight: If you pet’s weight is stable, then treatment is working. If your pet is losing weight, make an appointment. If you wait until the vomiting starts it may be too late.

 Blood pressure medication. Most patients will benefit from benazepril to regulate the blood pressure to the kidney. If your pet has systemic hypertension (high blood pressure) we may add amlodipine.

 Avoid NSAIDs, dehydration, and hypotension: Do not give aspirin, any over-the-counter pain reliever, or anti-inflammatory medication without specific approval of the veterinarian. There are some recent studies suggesting Onsior may be tolerated by kidney patients. Tramadol, Adequan, and glucosamine/ chondroitin are generally safe. Your pet will become dehydrated much more easily than in the past. A few bouts of diarrhea or vomiting can make fluid therapy necessary. Since anesthesia drops blood pressure, your pet will need IV fluids any time they “go under.”

 Appetite stimulants: If we have ruled-out other illness, mirtazapine may help.


 Anemia: Most patients in CRF are somewhat anemic. In advanced cases, the anemia may become severe enough to require treatment. Anemic pets are weak, tired, and have pale gums and eyelids.

 Rechecks: patients in early kidney disease (stage 1 and 2) are scheduled for rechecks and blood work every 6 months. Sicker patients come in every 3 months.


What to expect: The long term prognosis and life-expectancy for a CRF patient can vary from days to years from time of diagnosis. One of the best tools for forecasting your pet’s future is the initial response to treatment. For example, if you pet is not eating and vomiting, we may hospitalize for 3 days of IV fluids, then recheck blood work. Well-controlled renal failure patients enjoy comfortable lives, usually for months or even 2-3 years.

Regardless of the eventual course of your pet’s illness, at some point we are likely to recommend euthanasia. Unfortunately, the final days with end stage renal failure involve suffering that we desire to spare your pet. We are honored by the trust you place in us to care for your pet and it is essential that we communicate honestly about this topic. We will do every thing in our power to make this final visit as smooth and painless as possible.