|
Client Library
RENAL DISEASE = KIDNEY FAILURE
| About Renal Failure |
Renal failure is the medical term for a kidney that has
lost it's function to concentrate urine and filter toxins from the blood
into the urine. The degree of renal failure is measured by a number of
clinical & laboratory parameters. For any of these values to be
abnormal, more than 2/3 of the kidney function must be lost.
Values include:
- Specific gravity of urine (concentration)- will be low if
kidney can not concentrate the urine
- BUN (blood urea nitrogen)- blood test- will be greater than 30-
BUN is a blood toxin filtered by kidney
- Creatinine- blood test- will be greater than 2.0 if kidney not
filtering well- another blood test
- Phosphorus- blood test- increased in chronic renal failure
- Urine protein- elevated level of protein compared to urine
concentration- kidney leaks protein from blood
- Urine production- decreases or stops when the kidney is so
damaged, that the kidney literally shuts down.
These are only a few of the most common markers of kidney function.
The veterinarian will use results of other lab tests, radiographs (x-rays),
ultrasound, ultrasound, & possibly kidney biopsy to diagnosis renal failure
and more importantly classify it as acute vs chronic disease. |
| Acute vs
Chronic Disease |
| Acute renal failure
occurs over a short period of time and is usually attributed to a toxin
(antifreeze, some antibiotics,) or underlying medical condition (infection,
cancer, heat stroke, multiple organ failure etc). In acute renal failure,
the kidney shuts down and stops making urine, termed anuric. Without
aggressive emergency therapy, the patient will die due to electrolyte
imbalances (high potassium) causing the heart to fail. Acute renal failure
can happen in any aged animal.
Chronic renal failure occurs as a
progressive disorder which develops over time as more than 2/3 percent of
the kidney is damaged and ceases to function. Chronic renal patients
are usually older pets who slowly waste away with no
obvious sickness other than vague signs such as loosing weight, decreased
appetite, increased drinking and urinating, and occasional vomiting. At some
point however, the animal is no longer able to compensate for the kidney’s lack
of function, and the pet acutely decompensates- throwing the animal into
clinical renal failure. The patient appears to become very sick
in a short time though the damage has really been accumulating for a long
period- many times over years. A common feature of chronic renal
failure is a non-regenerative anemia. |
| Symptoms- Acute renal failure |
|
|
| Symptoms- Chronic renal failure |
- PU/PD (urinates lots, drinks lots)
- Chronic weight loss- becomes very thin- skin over bones
- Chronic anorexia
- Lethargy/weakness
- Chronic vomiting
- Ulcers in mouth
- Pale mucus membranes (gums)- from chronic anemia
- Possible swollen belly from low blood protein (ascites)
|
| Diagnosis |
| In both acute and chronic renal failure, the
diagnosis is based on urinalysis and blood work. With either
type of renal failure, the blood work will show increased levels of
BUN, creatinine,
potassium, phosphorus, and calcium- all substances that the kidney
eliminates in the blood. When kidney function deteriorates, these
substances build up in the blood. Additionally, the urine is always
checked for the specific gravity which equals the concentration of the
urine. In both types of renal failure, the urine will be very dilute as the kidney looses the ability to concentrate causing the production
of large amounts of dilute urine. In pets suffering acute renal failure,
the kidney can shut downs and makes little or no urine. Both radiographs
and ultrasound show changes in the kidney shape, size, and architecture.
Chronic renal failure- Owners frequently report that their pets have
become completely anorexic, have been vomiting, or suffer chronic
constipation. On physical exam, pets with chronic renal failure are often
very thin (can be emaciated), weak, dehydrated, and have a rough dry hair
coat. The kidneys are small, asymmetric, and feel bumpy. Pets are usually
anemic (low red blood cells) with chronic renal failure and have severe oral
ulcers from the high levels of BUN & creatinine.
Acute renal failure patients are usually younger animals who have
suddenly become very sick in a short period of time. Often very sick with a
primary renal toxin such as antifreeze, or is suffering another serious
illness such as heat stroke, or Leptospirosis, a lethal bacterial infection.
Pets with acute renal failure can therefore present with a plethora of
clinical signs. Typically the kidneys are smooth and enlarged or normal
sized. |
| Therapy |
- Acute renal failure requires very intensive therapy aimed at
re-establishing urine production, and rebalancing electrolyte imbalance
(especially high potassium) by keeping the blood flow to the kidney high
as well as flushing out the kidney (IV fluid diuresis). Underlying
problems must be treated aggressively with any combination of IV fluids,
antibiotics, diuretics, blood pressure medication, dialysis etc.
Even with intensive 24 hour care, these animals can die if the kidney
function does not return after an acute insult to the organ such as a
toxin.
- Chronic renal failure is treated with aggressive diuresis (IV fluids for several days in hospital) aimed at
flushing out the kidney, restoring the electrolyte balance, and lowering the
BUN and Creatinine levels in the blood. Anemia is treated with Erythropoetin,
a drug that stimulates red blood cell production. Anorexia is treated with
appetite stimulants. All cats should receive ongoing therapy with fluids
given under the skin 1-3 x/week once the major IV diuresis is complete.
|
| Prognosis |
-
Acute renal failure is highly variable- depending on the underlying source
of the kidney insult. Causes
of acute renal failure that carry a grave prognosis
include ethylene glycol (antifreeze) toxicity, heat stroke, septic shock,
long standing urinary blockage.
-
Chronic renal failure- fair to poor if
diagnosed in the early stages and treated with SQ fluids several times a
week as an ongoing maintenance therapy. If diagnosed in the end stages, the
prognosis is poor to grave.
-
Cats do much better than dogs with similar renal
values and can live comfortably with moderately elevated values.
-
Dogs in general do very poorly with even mild
increases in kidney values.
|
|
