Kidney Failure in Dogs: What Happens In The Dog’s Body When The Kidneys Fail To Function Properly?

Last time, I talked about (and hopefully clarified) some of the confusing terminology associated with diseases affecting the canine kidney.

I touched upon the basics of both acute kidney failure (or acute kidney injury, and chronic kidney failure.

Kidney Failure in Dogs: What Happens In The Dog's Body When The Kidneys Fail To Function Properly? Acute and chronic kidney failure.

Today, I’d like to go over what all this means for the dogs in our lives.

In other words, what happens to the body when the kidneys fail to function properly?

There are some significant differences between acute kidney injury and chronic kidney failure. Let’s look at the typical symptoms of each and why they develop. Note there will be a lot of overlap.  I’ve highlighted the important differences for you.

Acute Kidney Injury

Dogs suffering from acute kidney injury have some combination of the following clinical signs:

  • lethargy
  • depression
  • behavioral changes (they often seem dull and “out of it”)
  • loss of appetite
  • increased thirst
  • bad breath
  • vomiting (possibly containing blood)
  • diarrhea (possibly dark and tarry, indicating the presence of digested blood)
  • ulcers may develop in the mouth or elsewhere in the gastrointestinal tract
  • abdominal pain
  • respiratory difficulties
  • urine production may be normal, increase, decrease, or dog might not urinate at all
  • blindness
  • seizures
  • abnormal bruising

These symptoms result from the changes that occur in the body of a dog suffering from acute kidney injury:

  • Metabolic waste products (e.g., BUN and creatinine) build up within the body
  • Changes in body chemistry occur.  For example, potassium and phosphorus levels rise.
  • Because of the kidneys’ inability to conserve water, urine becomes dilute and the dog becomes dehydrated.  Typically, urine production increases initially, but it may decline or eventually stop altogether as kidney damage worsens.  If urine production stops and fluid therapy continues, dogs may actually become overhydrated.
  • Blood pressure can become abnormally high. This may lead to the retina detaching from the back of the eye and blindness.

Chronic Kidney Failure

With chronic kidney failure, dogs typically suffer from:

  • lethargy
  • depression
  • behavioral changes (they often seem dull and “out of it”)
  • loss of appetite
  • increased thirst
  • weight loss
  • muscle wasting
  • bad breath
  • vomiting (possibly containing blood)
  • diarrhea (possibly dark and tarry, indicating the presence of digested blood)
  • ulcers may develop in the mouth or elsewhere in the gastrointestinal tract
  • respiratory difficulties
  • increased urine production
  • blindness
  • seizures
  • abnormal bruising

When a dog suffers from chronic kidney failure:

  • Metabolic waste products (e.g., BUN and creatinine) build up within the body
  • Changes in body chemistry occur.  For example, phosphorus levels rise and potassium levels decline. 
  • Because of the kidneys’ inability to conserve water, urine becomes dilute and the dog becomes dehydrated.
  • Blood pressure can become abnormally high which may lead to the retina.
  • The kidneys stop producing adequate amounts of erythropoietin. Erythropoietin is a hormone that stimulates red blood cell production. With deficient production, the dog becomes anemic.

The take-home message? 

Inadequate kidney function has an adverse effect on the entire body:

  • eyes
  • circulatory system
  • brain
  • GI tract
  • etc.

This explains the myriad of clinical signs associated with kidney disease. Treating it can be a juggling act.

Related articles:
Kidney Disease: Say What?

Further reading:
Laboratory evaluation of kidney disease

4 Comments
  1. I can see how kidney failure could be difficult to identify right away since it can affect so many different areas. A couple of my (human) friends have had kidney transplants, it is a shame that doesn’t seem to be an option for dogs.

  2. We know a great deal about renal issues – unfortunately – as our heart pup, Mattie succumbed after a 3-year battle. But, he was always happy, and we made sure that he lived the best life possible. Thanks for the great explanation.

  3. Marjorie Dawson

    I know we can’t combat kidney failure but we can do a lot to make sure our dogs and cats are comfortable can’t we? Our Harvey has Probonix probiotics and they help his gut work better (and no runny poop!).

    There is a lot here for dog owners to take on board, and I hope all of them read your post. Thank you.

Share your thoughts