Chronic kidney disease (CKD)

Kidney disease is a general term to describe several conditions that can affect the kidneys or damage kidney cells. Some types of kidney disease are reversible but chronic kidney disease is a progressive disease that is irreversible. However, pets can sometimes have a good quality of life for many years after being diagnosed with chronic kidney disease.

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Kidney disease is the term used to describe several conditions that can affect the kidneys or damage kidney cells. If kidney disease progresses, it can lead to kidney failure and death. The medical conditions that can be associated with kidney disease include:

• Nephritis (infection of the kidneys, including the spread of systemic diseases, eg leptospirosis, Lyme disease, that can cause kidney damage)
• Nephrotoxicosis (damage to kidney cells associated with a drug or poison, eg antifreeze)
• Polycystic kidney disease (genetic condition in which kidney cells become cysts, losing their ability to function properly)
• Kidney stones
• Heart failure (heart disease can decrease the blood supply to the kidneys, which can damage kidney cells)

The kidneys are responsible for several important functions in the body, eg:

• Eliminating waste products through the urine
• Producing a hormone involved in the production of red blood cells
• Helping to maintain the body’s fluid balance/hydration
• Participating in the breakdown and elimination of many types of drugs
• Helping regulate levels of important electrolytes such as potassium and sodium

Kidney disease reduces the kidneys’ ability to carry out these functions, resulting in illness and (often) further progression of disease.

Chronic kidney disease occurs when the kidneys cannot effectively eliminate waste products, maintain hydration, and help regulate the balance of electrolytes in the blood. However, chronic kidney disease does not mean that the kidneys stop producing urine. In fact, because the kidneys can no longer concentrate urine, increased urine production is often one of the signs associated with this condition. Urine production does not stop completely until chronic kidney disease has progressed to the very end stage (kidney failure). 

Kidney damage can be acute, “acute kidney injury” (occurring over a period of hours or days) or chronic, “chronic kidney disease” (occurring over a period of weeks to months or longer). Acute kidney injury can be reversible in some cases, whereas chronic kidney disease is irreversible. It is important for your veterinarian to distinguish whether your dog has an acute kidney injury or chronic kidney disease when they are first diagnosed, but this is not always straightforward. 

Chronic kidney disease (CKD) can be caused by conditions such as polycystic kidney disease or kidney stones, and an age-related decline in kidney function in senior pets. It tends to be progressive, ie it gets worse over time. Although not reversible, it is often possible to slow the progression of CKD and manage some clinical signs so that your pet is more comfortable.

The clinical signs of CKD often start off as very mild, becoming worse as the disease progresses:

• Vomiting
• Appetite loss
• Increased drinking and urination
• Dehydration
• Lethargy (tiredness)
• Weight loss
• Constipation
• Decreased grooming
• Drooling (due to nausea or ulcers in the mouth).

Your veterinarian will want a medical history of your pet. Your veterinarian may ask about any medications or supplements your pet has received, changes in appetite, drinking, or urination, weight loss, previous illnesses, or any current signs of illness.

Diagnosis of kidney disease may require a combination of several tests, eg:

• CBC and chemistry profile: the CBC (complete blood cell count) shows the numbers of red blood cells (needed to carry oxygen to all the body’s tissues), white blood cells (needed to help fight off infection), and platelets. The kidneys are involved in the production of red blood cells so pets with CKD may have low numbers of these cells. The white blood cell count may also be abnormal if infection is present. The chemistry profile measures the levels of several substances that can change if there is a problem with the kidneys, such as CKD.
• Urinalysis: a urine sample from your pet can provide information about how well the kidneys are working. Urine that is too dilute or contains material that should not be present can indicate that a pet may have kidney disease.
• Radiography (x-rays): X-rays of your pet’s abdomen may show kidney stones or abnormally shaped or sized kidneys.
• Ultrasonography: ultrasound of the abdomen can be used to examine the kidneys. It can detect masses, cysts, or other problems that can contribute to CKD.

CKD is a progressive, irreversible condition. While it cannot be treated or cured, it can be well managed in many cases. Effective management may slow progression of disease and improve the pet’s quality of life.

Hospitalization and intensive care may be required before your pet becomes stable enough to continue recovering at home. Longer term, medications and dietary changes can often effectively manage the condition. Dogs with high levels of protein in their urine will require treatment with medication to reduce urine protein loss and may also require anti-clotting medication. All dogs with CKD are likely to benefit from a protein and phosphate restricted diet and your veterinarian will discuss options for this with you. Your dog may require medication for high blood pressure, electrolyte imbalances or anemia. Your veterinarian may recommend periodic blood testing and urine evaluations to assess your pet’s response to management and determine how quickly the disease is progressing. Your veterinarian will evaluate your pet and discuss the best methods of management with you.