Kidney Disease in Dogs: An Overview

Dog Breeds

nce a significant portion of functional kidney tissue has been destroyed, the dog becomes increasingly unable to filter and excrete waste products, causing them to build up to toxic levels in the blood.

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Definition of Kidney Disease

Renal disease is a general term for the dysfunction, impairment or failure of one or both kidneys. The kidneys are responsible for filtering nitrogenous and other waste products from circulation and excreting them in urine. The kidneys also produce a number of essential hormones and help regulate the concentrations of hydrogen, sodium, potassium, phosphate and other substances in bodily fluids. The kidneys are involved calcium metabolism, phosphorus production, blood pressure regulation and circulating red blood cell volume. Once a significant portion of functional kidney tissue has been destroyed, the dog becomes increasingly unable to filter and excrete waste products, causing them to build up to toxic levels in the blood.

Causes of Canine Kidney Disease

Canine kidney disorders can be classified into those that are chronic and those that are acute.

Chronic kidney disorders are caused by long-term insult to the kidneys which, over time, damages their ability to adequately concentrate urine and remove wastes from circulation. As kidney function deteriorates, the dog retains nitrogen, acids, ammonia and other toxic substances in its blood and tissues, causing a condition called uremia. Chronic kidney disease can be caused by trauma, congenital abnormalities (present at birth), chronic urinary tract obstruction, kidney infection (pyelonephritis), kidney stones (uroliths), cysts (polycystic kidney disease), exposure to renal toxins (nephrosis; can be caused by aspirin, butazolidin, ibuprofen and prolonged administration of certain antibiotics), lymphoma, nephritis (inflammation associated with infectious diseases such as hepatitis, ehrlichiosis, leptospirosis, Rocky Mountain spotted fever, systemic lupus erythematosus, chronic pancreatitis and Lyme Disease, among others), advancing age and a number of other disorders.

Acute kidney disease appears abruptly and can be caused by venomous snake or insect bites, complete obstruction of the urinary tract (tumor; urolith/calculi/stones), trauma, shock (insufficient blood flow to the kidneys), rupture of the urethra or bladder, bacterial or viral infection, congestive heart failure (inadequate blood flow to the kidneys), hypoadrenocorticism (Addison’s disease), prolonged anesthesia and exposure to or ingestion of renal poisons (especially antifreeze, heavy metals, raisins, grapes, Easter lilies and rat bait [rodenticide containing cholecalciferol]). If appropriate treatment is provided quickly, it may be possible to prevent permanent kidney damage in dogs with the acute onset of kidney disease.

Prevention of Kidney Disease in Dogs

The best way to prevent chronic kidney disease is to have annual blood and urine tests to assess kidney function and overall health, especially in aging dogs. Owners also can manage the risk of kidney disease by feeding their dogs a high-quality, nutritionally balanced diet and providing free access to fresh water at all times. Antifreeze, human medications, household cleaners, pesticides, rodenticides, fertilizers, batteries and other potential renal toxins should be kept well out of reach of all companion animals.

Special Notes

One of the most troubling aspects of kidney disease is that affected dogs usually do not show clinical signs until their kidneys are severely damaged. Symptoms typically do not appear until roughly 75% of functional kidney tissue has been destroyed. The clinical signs of both acute and chronic kidney disease are largely nonspecific and seem to appear suddenly, even though the disease probably has been progressing for some time. Chronic renal disease cannot be cured, but it may be managed with medication, dietary modification and other supportive therapies.

Preventing Kidney Disease in Dogs