Canine Kidney Disease, Acute and Chronic

In previous Caring for Pets entries, we’ve covered what the kidneys do, what causes kidney disease, and how dogs with kidney disease feel. Now, let’s consider the two major classifications of kidney disease, acute and chronic, because they are vastly different and require different approaches.

The difference between acute and chronic kidney disease
When kidney disease hits a pet with sudden, severe illness, it’s called acute kidney disease or acute renal failure (ARF). When kidney disease sneaks up slowly, destroying kidney function bit by bit and causing a progressive illness, it’s called chronic kidney disease or chronic renal failure (CRF).

Major differences between ARF and CRF include
• Severity and affect on longevity
• Urine production
• Instigating factors

Difference in ARF and CRF Severity and Longevity
Dogs with acute kidney disease can die within a few hours. In contrast, a pet with chronic disease may live for months or years. A pet with acute disease requires hospitalization with intensive emergency care, and the best indication of how the pet will do is how well it responds to treatment. A pet with chronic disease is managed at home with clinic visits every 3-4 months.

Many dogs with chronic disease have such a gradual progression of symptoms that the family is unaware the pet is ill until the pet is brought in for its annual physical exam with blood and urine tests.

Dogs can have both ARF and CRF if slowly progressive disease destroys so much of the functioning cells that failure of the entire organ occurs.

Difference in ARF and CRF Urine Production
With acute renal failure, no urine is produced (anuria) and no wastes are cleared from the body so that urea builds up within the blood (uremia). In contrast, dogs with chronic renal failure produce an excessive amount of urine and clear some waste products. The more urine a dog with CRF produces, the more it needs to drink; this combination of increased drinking and urination is called polyuria (PU) and polydipsia (PD) or PUPD.

Although dogs with PUPD and are able to clear some waste products, over time this clearance decreases and uremia develops. The dog’s brain and other organs will tolerate slow increases in uremia much better than they will tolerate sudden increases. Thus, when blood tests show uremia, we are better able to predict how the pet will do if we know the rate at which the uremia developed.

Difference in ARF and CRF Instigating Factors
Acute renal failure can be brought on by medications (lasix, NSAIDs like Rimadyl, Meloxicam & Etogesic, cepholosporins, aminoglycosides), toxins, heat stroke, shock, transfusion reaction, infection such as leptospira bacteria, and blockage in the renal system by stones or tumors.

Chronic disease can be brought on by long-term infection or medication use, genetic malformation and malfunction, cancer, and aging.

Canine kidney disease is not the end of the world; many dogs can live months or years with minimal illness if we handle their illness wisely. The more we understand about kidney disease, the easier it is for us to manage it. In previous Caring for Pets entries, we’ve covered what the kidneys do, what causes kidney disease, and how dogs with kidney disease feel. In upcoming discussions, we’ll cover signs and symptoms that a dog has renal failure, tests and treatment.