Dogs,  Cats

Kidney disease in cats and dogs – everything you need to know

One of the questions I get relatively often from my friends is, “My pet was diagnosed with kidney disease, what does it mean?! What should I do?!”. I know it’s scary, especially if your reference point is the acute kidney failure experienced by humans. So first of all, take a deep breath and try not to panic. Easier said than done, I know… but hear me out.

Kidney disease is a reality that many pets, particularly seniors, face. While it’s undoubtedly a serious condition, it’s essential to recognize that it comes in various stages. Sometimes, the path to managing it is as “simple” as making adjustments to your pet’s diet.

Our cherished furry friends are increasingly vulnerable to renal challenges. The culprits may include the natural progression of age, the growing impact of environmental pollution, the shift toward urban living, and, regrettably, often unscientific feeding habits.


While I am a veterinarian, this article is not intended to replace professional veterinary advice. If you have any medical concerns about your pet, consult your vet immediately. Always seek professional assistance if you are unsure of your pet’s health.


cat and dog cuddling
Photo by Snapwire

Risks and prevalence of kidney diseases in cats and dogs

At the clinic, we mostly see renal problems in dogs over 8 years old. Appropriate nutrition is therefore important, especially when caring for an older dog.

There is also a breed predisposition (with Labrador Retriever and German Shepherd at the top) and gender predisposition (males are more susceptible than females). If you want to know more here are 2 studies you can read – Epidemiological observations on canine renal disorders and Incidence of chronic kidney disease in dogs.

Chronic kidney disease (CKD) also affects an estimated 1% to 3% of all cats. As with dogs, the prevalence also increases with age.

As many as 30% to 50% of cats older than 15 years of age have CKD. So again, it’s something you need to think about when taking care of a senior cat.

So if you have an older dog or cat, you should know a few things about kidneys and kidney disease. Sadly, there’s a high chance that you’ll have a renal patient at home at some point 😕

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What do kidneys do and why are they so important

Just like humans, cats and dogs have 2 kidneys. Each kidney is made of thousands of microscopic nephrons, which work as small filtration units.


As is often the case, there is good news and bad news. Unfortunately, the downside is that you simply can’t live without them.

On a brighter note, the upside is that kidneys possess a remarkable compensatory ability. Healthy kidney tissue has the capacity to offset a significant amount of damage. This is why, despite the necessity for two kidneys, living with only one is feasible and manageable.

Kidneys have many vital functions, such as:

  • filtering blood and excreting metabolic “waste” via urine
  • producing hormones that help regulate blood pressure and red blood cell production
  • regulating the blood concentration of some essential nutrients including calcium, phosphorus, potassium, sodium, chloride, and magnesium

As you can see, if something suddenly goes wrong, it can be a big problem… 🙁

kidney disease in cats and dogs

Kidney disease, also known as renal disease, refers to the impairment of kidney function, affecting the organ’s ability to filter waste and maintain the body’s balance of fluids and electrolytes.

In both cats and dogs, this condition can manifest in various forms. The management and prognosis depend heavily on the severity of the disease.

As you probably know, kidney disease progresses through stages, each presenting distinct challenges and considerations:

  • Stage 1 (Early): Mild kidney damage with very few noticeable symptoms. The kidneys can still compensate for the loss of function. The prognosis is generally positive with lifestyle adjustments and monitoring.
  • Stage 2 (Mild to moderate): Gradual decline in kidney function; symptoms become more apparent. While kidney disease is not curable, management strategies can significantly slow progression.
  • Stage 3 (Moderate): Significant loss of function; clinical signs intensify. Your pet needs intensive management, focusing on symptom relief and slowing further decline.
  • Stage 4 (Severe): Critical decrease in kidney function, demanding immediate attention. Kidney failure, also called end-stage renal disease (ESRD), is the last stage of chronic kidney disease when kidneys function at less than 15% of normal.

Early detection is pivotal in managing kidney disease effectively. The sooner we know about it, the better the prognosis.

Acute and Chronic renal failure in cats and dogs

Unfortunately, kidney diseases are relatively common. We can roughly divide them into acute and chronic.

Acute renal failure is the sudden loss of function that requires rapid medical intervention. It can be caused by several factors, such as poison ingestion, trauma, or illness. It’s an acute life-threatening condition that needs rapid medical intervention.

In the veterinary clinic, we see mainly chronic kidney disease with gradual loss of function. It’s a chronic progressive disease. This means that the process cannot be reversed, we can only slow it down (or stop it in some cases, if we are lucky).

There are several factors that can trigger chronic kidney disease. It can be a hereditary or an inborn problem or it can be triggered by inflammation or infection.

Renal insufficiency is another term for the poor function of the kidneys.

As I said before, kidneys have a huge compensation capacity. It is possible to live with only one kidney. However, on the other hand, animals with early stages of chronic kidney disease do not show any signs that there is a problem. There are no symptoms, nothing to alert you that something is wrong.

Symptoms of renal disease in cats and dogs

Due to the kidneys’ inherent ability to compensate for the loss of function, observable clinical symptoms only emerge when a considerable amount of kidney tissue is damaged and their function is impaired.

Only when there is a significant decrease in function (usually more than 70%) can we see some of the following symptoms:

Signs of kidney disease in dogs and cats:

  • Excessive thirst – this can be a good indicator that there is something wrong with the kidneys
  • Nausea, vomiting, diarrhea
  • Lack of appetite, and weight loss
  • Increased frequency and amount of urination
  • Lethargy, the animal doesn’t want to play… the owners often say that their pet seems sad

As you can see, these symptoms are pretty general, and you can’t really tell what’s going on without further diagnostic tests.

a picture of kidneys

Diagnosis of kidney disease in cats and dogs

For diagnosis, you need at least blood and urine analysis. Your vet may also recommend further specific tests such as x-rays, ultrasound, biopsies, or measuring arterial blood pressure.

Standard blood tests can detect chronic kidney disease when 75% of nephron function is lost, meaning that most kidney tissue is already irreversibly damaged. At this point, there is a very rapid onset of severe symptoms which might suggest a bout of acute kidney disease when, in fact, this is simply the next stage of underlying and undetected chronic kidney disease.

Fortunately, there is a blood test (SDMA test) that can detect kidney damage with only a 25% loss of function. This basically means that it can detect the early stages of the disease when we don’t see any symptoms yet.

Because chronic kidney disease affects mostly older animals, blood analysis should be included in the geriatric assessment. I would strongly recommend the SDMA test as well for early diagnosis.

Treatment of kidney disease in cats and dogs

The therapy depends on the individual patient. It can range from a special renal diet to medication or even hospitalization in an acute phase. In any case, it is a serious disease, so please follow your vet’s instructions.

Chronic kidney disease cannot be cured. The damage to the kidney tissue is irreversible. However, with the right therapy plan, we can slow the progression, improve the quality of life of your pet, and prolong life expectancy.

A pivotal aspect of managing kidney disease in pets involves implementing a tailored diet. A kidney-friendly diet aims to alleviate the burden on compromised kidneys, supporting overall health.

A diet that supports kidney function should have:

  • Low phosphorus levels: Minimizing phosphorus intake is essential, as impaired kidneys struggle to excrete excess phosphorus. Your pet will need a specialized veterinary diet with reduced phosphorus levels.
  • High-quality proteins: Opting for high-quality, easily digestible protein sources ensures that essential nutrients are provided without overtaxing the kidneys.
  • Omega-3 fatty acids: Most veterinary diets Include omega-3 fatty acids to support renal function and help manage inflammation.

And I know you’ll ask, so yes, in case of chronic renal disease, your pet will need to stay on this specialized diet for the rest of his life.

Despite the seriousness of the illness sometimes all you need to do is change the food to a renal diet. Appropriate nutrition is the cornerstone of treatment for chronic kidney disease.

Renal diets are veterinary diets developed specifically for patients with kidney problems. They have adapted levels of phosphorus and high-quality proteins, help maintain fluid and electrolyte levels, and help prevent metabolic acidosis. 

Treatment options depend on the severity of the case. Each patient is different and the therapy aims to slow down the disease progression and alleviate the symptoms.

Your pet will need several medications and adjustments. I’m not going into details here, as each case is different and needs a unique therapy plan.

Some pets need to be hospitalized, some only need a dietary change, and some need daily medications and supplements.

But even the best therapy plan will fail without your full cooperation. Please follow your vet’s recommendations and let him know if you observe any new signs or changes in your pet’s behavior.

Your pet needs to be closely monitored. We might need to adjust their therapy plan from time to time. Regular veterinary check-ups are absolutely necessary when dealing with this disease.

Discovering that your furry companion is grappling with kidney disease can be an emotional journey. Talk to your vet whenever you need to. He’ll be there for you, believe me.

If you follow your vet’s recommendation you can still have many years together with your pet, the key is early diagnosis 🙂

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What to read next:

🐶 For dog parents:

😻 For cat lovers:

References:

  1. Brown SA. Linking treatment to staging in chronic kidney disease. In August JR (ed): Consultations in Feline Internal Medicine. St. Louis: Elsevier Saunders, 2010, pp 475-482.
  2. . Polzin DJ, Osborne CA, Adams LG, Lulich JP. Medical management of feline chronic renal failure. In Kirk RW, Bonagura JD (eds): Kirk’s Current Veterinary Therapy XI. Philadelphia: Saunders, 1992, pp 848-853.

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