Chronic Renal Failure in Dogs and Cats

http://www.vetmed.wsu.edu/ClientED/anatomy/dog_ug.asp#Kidney


Chronic renal failure (CRF) in dogs and cats is the deterioration of renal function to the point where the kidney is no longer able to perform its primary functions. The kidney’s primary functions are to filter metabolic wastes from the bloodstream and excrete them into the urine; perform hemostatic functions such as control red blood cell production, blood pressure; and to perform endocrine functions such as in the degradation of hormones. Additionally, the kidney plays a primary role in the synthesizing of active vitamin D.

Chronic renal failure is a process that occurs over a period of time, longer than a month, and is primarily due to the presence of renal disease. Renal disease often goes undetected in most patients for extended periods of time. Renal disease is usually not discovered until the damage to the kidneys has caused irreversible renal failure to occur.

The causes of chronic renal failure can be due to many factors. Renal failure caused by injury is not as common as congenital and hereditary conditions. However, other metabolic factors that can cause kidney disease other than these are much more commonly found.

Dogs and cats are susceptible to a great variety of poisons that can cause renal failure. Additionally, diseases such as leptospirosis, cancer, amyloidosis, pyelonephritis, glomerulonephritis, immune-complex disorders, ischemia, hypercalcemia and many others are the more common causes of chronic renal failure in pets today.

Dental disease is a primary factor in kidney disease. The bacterium that develops from advanced dental disease enters the blood stream. These bacteria can settle in multiple organs and damage the kidneys, heart, and liver of dogs and cats.

Age also plays a role in kidney failure. As the pet ages so do the organs that function within the body. Large clusters of proteins are harder for the kidney to process at an older age. These proteins can contribute to renal damage. This is one important reason why special diets are recommended for the senior pet.

The most common clinical presentation of the dog and cat with CRF is dehydration, anorexia and weight loss; but many other symptoms can be exhibited such as diarrhea or constipation and anemia. Neurological impairment is seen clinically in the advanced cases of CRF. It must be noted that these symptoms can be indicative of other disease processes; thus requiring laboratory testing and other diagnostic procedures as the primary methods of the clinical evaluation of CRF.

The progression of CRF is a sequence of events involving the key component of the kidney anatomy. The kidney is most easily described as a primary filtering mechanism of the body. The primary functioning component of the kidney is the nephron. In fact, the number of nephrons that are present in the kidney usually determines kidney size.

The nephron itself is made of several components. The main components of the nephron are the renal corpuscle, proximal tubule, loop of Henle, distal tubule and collecting duct. Each one of these components has additional individual structures within them. When the nephron is damaged it ceases to perform its filtering functions. This leaves the remaining functioning nephrons to carry the burden of filtering the blood that is flowing through the kidney.

After a period of time the disease may continue to damage other nephrons. If it is a congenital or hereditary condition, more than likely the normal nephrons were forced to work under a heavier than normal work load due to the lack of normal kidney cells. This heavy work load can cause additional damage to the kidneys. It must be noted that many animals that have a hereditary or congenital kidney disease usually do not live past one year of age.

More and more nephrons are destroyed as the kidney disease progresses. This destruction of nephrons usually results in the reduction in kidney size also. Even if the kidney disease has been treated sometimes the destruction of the nephrons will continue unchecked. Most clinical signs of CRF usually do not develop until after 70% of the normal kidney function is destroyed. This is why routine laboratory screening tests are vital to the health and well-being of the pet.




The process of chronic renal failure in the dog and cat can be quite complicated, involves many physiological processes, and can be caused by multiple conditions and diseases. While CRF can be managed successfully for a period of time it will eventually result in the death of the patient. However, it must be noted that cats are more responsive to extended periods of CRF management than dogs. The veterinarian in charge of the pet’s care will be able to develop the treatment plan that would be the most beneficial for each individual.

Pet owners can have their dogs and cats teeth cleaned on an annual basis which will help prevent many cases of chronic renal failure. This is probably the single most important thing that a pet owner can do to help prevent kidney disease. Regular bi-annual health checks with a veterinarian that includes laboratory blood testing and urinalysis are additional preventative measures that pet owners can take to help prevent chronic renal failure. At the very least, diagnostic tools will provide early diagnosis that can assist the veterinarian in the management of CRF. Additionally, feeding dogs and cats with a good quality food for the proper stages of its life is an important factor in disease prevention.

With the advances in veterinary medicine, more information on chronic renal failure is being discovered, resulting in the availability of more and better treatments. Kidney transplant procedures in the feline and canine patient are becoming more successful every year. While this method of treatment was first developed successfully in the cat, researchers are now getting favorable results in the canine patient. Currently, there is not a cure for chronic renal disease.