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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 dogs 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

  1. Canine and Feline Nephrology and Urology, Osborne, Carl, and Finco, Delmar R., Williams and Wilkins, pubs., 1995.

  2. Association of American Feed Control Officials Incorporated. Official Publication 1997. Atlanta: AAFCO, 1997

  3. "New Insights and Treatments of Kidney Disease, Part I.", Gearhart, Martha A., D.V.M., Dog World, March 1997.

  4. "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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