Kidney Disorders in Dalmatians
Urinary System: The Kidneys - Basics
Study Group on Kidney & Liver Disorders
Health & Research Committee
Dalmatian Club of America
This page by Former Director James E. Seltzer, Ph.D.
This site is intended to be
informative only. If your dog is suffering from a health problem, diagnosis and treatment should be based upon consultation
with your veterinarian.
Organization of the Urinary System
Among the body's principal organs, two hard-working kidneys control the balance
of water, acids/bases, and electrolytes. In addition, they detect, filter, remove and finally pass on for excretion toxic wastes from
the body. The kidneys also help regulate blood pressure, help regulate the calcium and phosphorus metabolism, and produce a hormone that
stimulates red-blood-cell production called erythropoiten. The kidneys are bean-shaped structures a few inches long in an adult Dalmatian
and somewhat narrower in width than in length. In adult dogs, normal kidney weight may vary from one-half to one percent of body weight
about a half pound in a Dalmatian. Yet from 10 to 20% of the total blood flow from the heart passes through these relatively small organs.
For an average adult Dalmatian they will process almost 200 gallons of blood each day, of which all is recycled except for a small fraction
that is converted to urine. From the kidneys, urine passes through small muscular tubes called ureters which empty into the bladder. The
bladder is a balloon-like structure bound with muscle. It is a storage site for urine until it can be eliminated from the body. When the
bladder empties, urine flows down the urethra to exit from the body.
When Things go Wrong
Kidney
disease is any destructive process within the kidney. Kidney disease is not
limited to any particular age or breed, but is one of the most common
medical problems of older dogs and is a leading cause of death. Depending
on the study, kidney failure is the second or the third leading cause
of death in dogs after heart disease and/or cancer. Furthermore,
autopsies done on older dogs reveal abnormalities in as many as 85% of all
kidneys examined in dogs over the age of five. Kidney disease may
have many different causes, including inherited defects, infections
and toxic substances. Frequently, the cause cannot be determined,
but with careful examination and testing, the severity of the disease
can be evaluated and a treatment protocol can be established.
The
kidneys have great reserve capacity, but if kidney disease destroys the kidney's
ability to perform properly, waste materials accumulate in the blood
and signs of actual kidney failure are likely to appear. Signs associated
with kidney failure are:
-
Increased thirst (Polydipsia)
-
Increased urine volume (Polyuria)
-
Weight loss
-
Weakness and exercise intolerance
-
Tendency to bleed or bruise easily
-
Dehydration (To test for this, gently pull the skin away from your dog’s
middle. If the skin does not immediately spring back, the dog
may be dehydrated.)
-
Stiff-legged gait and arched back (a sign of painful kidneys)
-
Little or no urine production
-
Loss of appetite
-
Poor hair coat
-
Depression
-
Vomiting and (less commonly) diarrhea
These signs may appear suddenly (acute renal failure) or develop slowly over
time (chronic renal failure), and they may be produced by diseases other than kidney disease.
Usually signs of decreased kidney function are not evident until more than two thirds to three fourths of
the total kidney function has been lost. The majority of adult dogs have suffered some kidney damage, and kidney damage is usually
progressive. Existing damage to the kidney cannot be repaired but surviving elements can compensate to take up the increased workload,
and medical and dietary therapy can help to slow progression of the disease. An early diagnosis is therefore important to be able to start
treatment at an early stage, sometimes even before clinical signs become apparent. Any measure that helps prevent the disease, delays the
age of occurrence, and slows the progression of this disease will help a dog live longer.
Diagnosis of Kidney Disorders
There are a number of lab tests (commonly, urinalysis and blood tests, less commonly, ultrasound and kidney
biopsies) that indicate whether the kidneys are functioning properly. When kidneys are working properly, they produce urine that is
typically more concentrated than the blood plasma. A dog should be able to concentrate urine above the specific gravity of 1.020.
If several urine samples taken during the day all fail to have a urine concentration greater than 1.020, that would be a sign that the
kidneys are not working properly.
Blood Tests
Blood tests should be performed as a part of the dog's veterinary examination. Creatinine (CREAT) is a
waste by-product of muscle breakdown and repair, and its production is nearly constant. Rising level of (blood) serum creatinine revealed
by periodic blood tests is a strong indicator of progressive kidney disease. Two other compounds frequently monitored are blood urea
nitrogen (BUN) and phosphorus (PHOS), but these are less reliable since they can be affected by diet.
Blood tests for minerals such as calcium, sodium, and potassium may also be abnormal in kidney failure, and
severe imbalances of any of these minerals create weakness and abnormal heart rhythms. However, this generally occurs only after BUN,
CREAT, and PHOS are elevated several times above the normal ranges. Each diagnostic laboratory will determine normal ranges for these
measurements, and those employed by your veterinarian may differ from those tabulated below. However, BUN concentrations above 75 mg/dl
are a strong indication that the kidneys are not doing their job. CREAT values above 2.5 mg/dl are not likely to occur for any reason other
than an inability of the kidneys to filter the creatinine from the bloodstream. Rising PHOS levels above 7.0 mg/dl are associated with
kidney damage. Falling total protein levels can occur with kidney failure, and anemia is not uncommon if the kidneys start to fail
completely.
Typical Blood Chemistry Reference Ranges
Test |
Canine |
BUN, mg/dl |
10-30 |
Calcium, mg/dl |
8.0-12.0 |
Creatinine, mg/dl |
1.0-2.0 |
Glucose, mg/dl |
65-130 |
Phosphorus, mg/dl |
3.0-7.0 |
Potassium, mE/L |
4.0-5.7 |
Protein (total), g/dl |
5.4-7.6 |
Sodium, mEq/L |
140-158 |
From College of Veterinary Medicine, Oregon State University,
Corvallis, Oregon, April, 1999 (Your diagnostic laboratory
may use different measurement units and/or reference ranges)
Urine Tests
A
urinalysis should be done routinely every year on every dog over six years
of age. Urine is the product of the kidneys and will reveal problems
long before blood work reveals any abnormalities. Additionally, any
sick dog should have a urinalysis done. Bacteria, traces of blood,
excessively dilute urine, protein, sugar are abnormalities that may
need further evaluation. Doing a routine urine protein-to-creatinine ratio
in older dogs is extremely important in the successful diagnosis
and management of progressive renal disease in older dogs. Not only
is kidney disease common, but it is easily missed on physical examination,
and even on blood tests in its earliest stages. The urine, however,
holds the key to revealing low-grade, chronic kidney disease. If discovered
early, specific treatment and appropriate dietary management can
prolong the life of an afflicted pet, or, in the case of a hidden
infection, halt the progress of the disease if diagnosed in time.
It is believed that once the kidney is significantly damaged progress of
the disease is inevitable; the working units of the kidney (nephrons)
continue to be lost due to the excessive work demands placed on those
nephrons still functioning.
Normal Findings - Fresh Canine Urine
Component |
Adult Dog |
Color |
Yellow |
Turbidity |
Clear |
Specific Gravity |
Minimum |
1.001 |
Maximum |
1.065+ |
Typical Range |
1.015-1.045 |
pH |
4.5-8.5 |
Glucose |
Negative |
Ketones |
Negative |
Bilirubin |
Trace to 1+* |
Occult Blood |
Negative |
Protein |
Trace* |
Protein-Creatine Ratio |
0-.3** |
RBC (per high-power field) |
0-5 (?) |
WBC (per high-power field) |
0-5 (?) |
Bacteria (per high-power field) |
Negative |
Crystals (per high-power field) |
Variable |
*in highly concentrated urine. **values from .3-1 are questionable,
values above 1 are abnormal.
From Canine and Feline Nephrology and Urology, Osborne, Carl,
et al,
Williams and Wilkins, pubs., 1995, p 202.
Treatment of Kidney Disorders
Once
chronic kidney failure develops it cannot be reversed, but there are measures
that can be taken to slow the progression of the disease and help
the dog live longer. On the other hand, acute kidney disease can
often be stopped, and many dogs recover completely once the underlying
cause is corrected.
Your
veterinarian will determine the proper treatment for your dog which may include
hospitalization, fluid therapy, as well as diet and medication. High
blood pressure, a common complication of chronic kidney failure,
may require periodic monitoring to evaluate progress.
Many
of the toxins building up in the blood are chemicals derived from the diet.
Nutrients in the diet that may contribute to progression of the disease
include protein, phosphorus and sodium. By limiting the intake of
these nutrients, while still providing an excellent quality diet,
it is possible to maintain your dog's nutritional status and reduce
production of toxic products. It also is important to provide enough calories
to prevent the body from breaking down its own tissues as a source
of calories, which only adds more toxic products. By reducing the
amount of waste products, animals often feel better, so they become
more inclined to eat and to be more active.
Water A major thrust of treatment for chronic kidney disease is to make
sure that your dog receives enough water and other fluids. Dogs that
do not receive enough fluids may become dehydrated, which decreases
the amount of blood flowing to the kidney to permit waste products
to be flushed out of the system. Signs of dehydration to watch for
include a dry, "tacky" mouth and loss of skin pliability, which causes
the skin to stick together when pulled away from the body. Access
to fresh water at all times is important. Do Not Restrict Water
for Any Reason, unless your veterinarian specifically requests you
to do so. Some animals drink more water when water bowls are refilled
frequently, and water may be added to the animal's food if it is
eating well.
Special Diets Special diets for patients with chronic kidney disease
are designed to limit the intake of protein, phosphorus and sodium,
while avoiding deficiency of any of these essential nutrients. Signs
of nutrient deficiency in animals fed these special diets include
muscle loss, poor haircoat and listlessness. These signs are not
specific, however, and may be associated with other problems. If you see
any of these develop in your dog, contact your veterinarian to have
them evaluated. You can feed your dog a commercially available veterinary
food, or cook a "kidney friendly" special homemade diet.
Prognosis
Prognosis
for acute renal failure largely depends on the severity of injury to the
kidneys. Short-term survival depends on whether the dog can live through
the worst part of the acute episode. Expert, mainly supportive, medical
care will allow some animals that would otherwise die to survive
the worst of their illness. Long-term prognosis for these dogs is
fair to good for those that survive the critical stage and begin to show
signs of recovery.
No
test can determine how long your dog will live with chronic renal failure.
Some animals tolerate kidney failure amazingly well, while others
with the same degree of kidney failure are very sick. Information
from the physical examination, response to treatments, general history
of well being, and laboratory data should provide the needed information
to provide the best care for your dog.
Prevention
Of
critical importance for a dog of any age is the avoidance of injury to the
kidneys either by physical causes or the ingestion of substances
that are toxic. Urinary tract infections that could possibly lead
to pyelonephritis should be treated by a veterinarian. Diseases such
as leptospirosis can have a severe impact on the kidneys and vaccinations
are available to assist in prevention. Certain medications such as
NSAIDS that are used to alleviate pain and a number of antibiotics
are known to cause kidney damage when used for prolonged periods;
this is especially true in the geriatric dog. Some common household
chemicals can cause acute renal failure; the most notorious of these is
the automobile anti-freeze, ethylene glycol, the ingestion of only
a tablespoon of which can be fatal to a medium size dog.
Problems
with maintaining healthy kidneys and aging are the most difficult to confront.
Should every dog over seven years of age be on a senior diet? Every
dog ages differently, and most dogs do very well on senior diets
because the protein levels are above adult maintenance minimal requirements.
However, many dogs are still leading active, working lives at 11,
12, or older. Service dogs, hunting dogs, and jogging companions may need
22 % protein to maintain condition. Similarly sick dogs, even ones
with kidney disorders, may need extra protein for coat condition,
muscle tone, and the preservation of a healthy immune system. What
older dogs don't need is mineral levels as high as those that are
recommended for growth and reproduction.
It
is generally agreed that protein alone does not cause kidney failure in the
normal dog. But it is likely that many dogs older than five are not
truly normal. Perhaps only 15% of senior dogs retain normal kidney
function. Studies like these are the impetus behind urging people
to feed a "senior" (protein restricted) diet to their dogs.
Classes
of Dog Food
|
All stages of
life – Satisfies AAFCO* standards for puppies, reproduction
and adults; commercial brands in this category typically contain
26-30% protein (AAFCO minimum 22%) and 12-20% fat (AAFCO minimum 8%). |
Adult maintenance
only – Satisfies AAFCO* standards for non-reproducing adults;
commercial brands in this category typically contain 20-25% protein
(AAFCO minimum 18%) and 12-16% fat (AAFCO minimum 5%). |
Senior –
Typically lower in calories, protein and fat, higher in fiber;
commercial brands in this category typically contain 16-20% protein
and 8-12% fat. |
Lite – Typically
lower in fat and calories; commercial brands in this category
typically contain 16-21% protein and 5-10% fat. |
*AAFCO (The Association
of American Feed Control Officials) sets guidelines and definitions
for animal feed, including pet foods. Percentages in DM (dry
measure) basis. |
In the opinion of some veterinarians,
the restriction of phosphorus is of greater value than protein restriction.
Some, but not all, protein sources are also high in phosphorus. Switching
from an "all stages of life" diet to an "adult maintenance only"
may be sufficient for many dogs; an actual "senior" diet may not
be necessary. However, vegetables and starches are very high in phosphorus;
this is why some "lite" formulas are often higher in phosphorus than
are adult maintenance diets. "Lite" formulas should not be considered
the equivalent of senior diets, but, regardless of the diet you choose, be
sure it is a reputable, name-brand product. Generic products have
no reputation to maintain and, consequently, do not always use quality,
fully digestible products.
Finally, the most important thing
you can do nutritionally for your dog is to be sure that your pet
is free of parasites and disease. The finest diet in the world will not
benefit a dog full of heartworms, hookworms, tapeworms, whipworms,
roundworms, or coccidia -- the parasites get all that great nutrition.
Similarly, a sick dog will lose condition even on a premium diet.
Not only should your pet be examined annually and kept on a heartworm
prevention program in those geographic areas where the parasite is common,
but a yearly stool and urine examination is necessary as well, especially
for the "senior" dog.
References
-
Canine and Feline Nephrology and Urology, Osborne, Carl, and Finco, Delmar
R., Williams and Wilkins, pubs., 1995.
-
Association of American Feed Control Officials Incorporated. Official Publication
1997. Atlanta: AAFCO, 1997
-
"New Insights and Treatments of Kidney Disease, Part I.", Gearhart, Martha
A., D.V.M., Dog World, March 1997.
-
"Managing a Renal Crisis," Gearhart, Martha A., D.V.M., Dog World,
vol 82, April 1997, pp 40-44.
K9Kidneys List
K9KIDNEYS
is a list for owners of dogs who are currently suffering from one or more
forms of kidney disorders. Emphasis of the discussions will revolve
around the current available veterinary therapies, and practical
management techniques. You can join this discussion group by subscribing
on-line at:
http://groups.yahoo.com/group/K9KIDNEYS/
Kidney Informational Links
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