What is Chronic Kidney Disease (CKD) in dogs?

Old boxer lying on a couchWhat is Chronic Kidney Disease (CKD) in dogs?

Chronic Kidney Disease (CKD) is a progressive and irreversible condition that affects the kidneys, essential organs responsible for filtering waste products and excess fluids from the bloodstream. This disease develops gradually over time, leading to a decline in kidney function and compromising the organ's ability to maintain proper electrolyte balance, regulate blood pressure, and excrete waste efficiently. 

There are many types (and causes) of kidney disease, so we always recommend speaking with your veterinarian if you suspect your dog may be at risk. While CKD can be a scary diagnosis, there are treatment plans available and your dog may be able to resume a healthy and comfortable life for years to come. In this blog post, we will explore some of the most common causes of CKD, early signs and symptoms, and potential dietary interventions to manage the disease. 

Types of Chronic Kidney Disease

There are two main types of CKD, and they are defined by the affected part of the kidney. The more common form of chronic kidney disease impacts the tubules, which is the part of the kidney that play a key role in urine formation and the elimination of waste from the bloodstream through urine. The second type is caused by a damaged glomerulus, acting as a filter for the tubules. The glomerulus is supposed to strain out waste products and pass them to the tubules to be eliminated as urine, while retaining essential substances (like protein).

Diagram of a dog's kidney

Diagram source

Causes of Chronic Kidney Disease

Common causes of CKD in dogs include aging, genetic predispositions in certain breeds, infections, exposure to toxic substances, and underlying health conditions like autoimmune disorders. The cumulative impact of these factors contributes to structural and functional changes within the kidneys, leading to their diminished capacity.

  • Aging: As dogs grow older, their kidneys undergo natural wear and tear, making them more susceptible to kidney diseases.
  • Genetics: Certain breeds are predisposed to kidney issues, emphasizing the importance of breed-specific health monitoring. Breeds like Bull Terriers, German Shepherds, and Cocker Spaniels are known to be more susceptible.
  • Infections: Bacterial or viral infections can lead to inflammation and damage to the kidneys, contributing to the development of CKD. 
  • Dental Hygeine: Dental disease can lead to chronic inflammation, which can release harmful bacteria from the mounth to the bloodstream. A dog’s kidneys can be overloaded by these toxins and can lead to kidney damage or disease over time.
  • Toxic Substances: Ingestion of toxic substances such as antifreeze or certain medications can harm the kidneys over time.
  • Other Health Conditions: Conditions like high blood pressure or autoimmune diseases can indirectly impact kidney function.

Symptoms of Chronic Kidney Disease

The progression of CKD is typically categorized into stages, ranging from mild to severe. In the early stages, dogs may compensate for the declining kidney function, displaying no apparent symptoms. However, as the disease advances, observable signs of kidney dysfunction become more evident.

  • Increased thirst and urination: Dogs with CKD often drink more water and urinate more frequently.
  • Weight loss: Unexplained weight loss may be a sign of reduced appetite and nutrient absorption.
  • Lethargy: Decreased energy levels and overall lethargy can be indicative of kidney dysfunction
  • Vomiting & diarrhea: Gastrointestinal issues may arise as the kidneys struggle to regulate fluid and electrolyte balance.

Diagnosing Chronic Kidney Disease

Early detection and intervention are crucial for managing CKD in dogs. Veterinarians may conduct blood tests, urine analyses, and imaging studies to diagnose and assess the severity of the condition. Once diagnosed, treatment strategies may include dietary modifications, medications to address symptoms and slow the progression of the disease, and supportive care to manage complications. Regular vet visits are important to stay on top of bloodwork and possible symptoms of early CKD. 

Nutritional Strategies for Managing CKD

Proper nutrition plays a vital role in managing CKD in dogs. Here are some dietary considerations:

Therapeutic Diets for CKD

Diets for dogs with CKD are often low in protein to reduce the burden on the kidneys. These diets typically also restrict phosphorus, potassium, and sodium/salt to reduce the burden on a dog’s kidney function. For example, one of the more popular therapeutic diets available commercially is Hill’s “k/d” line (also called “Kidney Care”), which is often available as a prescription diet.

Plant-Based Diets

Nephrologists (doctors that specialize in kidneys) typically recommend that humans with kidney disease or at a higher risk of developing kidney disease eat more plant-rich diets. Research in humans suggests that 1) people who eat a more plant-rich diet are less likely to develop CKD and that 2) people with CKD who eat primarily plant-based diets experienced lower all-cause mortality than those who ate primarily animal protein.

There have not been equivalent epidemiological studies in dogs, but a randomized feeding trial found that dogs that switched to a plant-based diet experienced a significant decrease in creatinine and blood urea nitrogen (BUN) levels compared to the group assigned to a meat-inclusive diet with equivalent protein. Creatinine and BUN are markers of protein metabolism, and elevated levels in blood tests can be markers of kidney dysfunction because the kidneys are either struggling to clear them from the blood or are having to ‘work harder’ to filter more byproducts of protein metabolism. A decrease in blood levels of creatinine and BUN can have many causes (particularly in healthy dogs), and more research is needed to understand if primarily plant-based diets improve renal function in dogs as has been demonstrated in humans. 

Many veterinarians recommend plant-based proteins for dogs with CKD and most vet-prescribed therapeutic kidney diets include primarily plant-based proteins. Plant-based proteins are naturally lower in phosphorus and sodium and are less acidifying (more alkaline) than animal protein, and limiting these nutrients decreases the amount of work kidneys need to do to filter blood. 

Similar to veterinary-prescribed diets, Petaluma’s plant-based formulas are relatively low in total phosphorus (~0.8% DW) and sodium (~0.2% DW). However, both diets are relatively high in protein, as higher protein levels are typically recommended to maintain strength in senior dogs that face a slowing metabolism and lean muscle loss. However, once a dog has been diagnosed with CKD, this elevated protein level may be inappropriate and place an unnecessary burden on already impaired kidney function.

As with any disease management, diet is one component and it's crucial to consult your veterinarian to determine the most appropriate nutritional profile for your dog's specific type of kidney issues. CKD in dogs requires a comprehensive approach that includes early detection, proper veterinary care, and a well-managed diet. By staying informed about the causes, recognizing symptoms, and working closely with your veterinarian, you can enhance your dog's quality of life and provide the necessary support to manage this challenging condition.

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