Understanding Your Dog's Kidneys
The kidneys perform several vital functions. They filter waste from the bloodstream, regulate essential minerals like potassium and sodium, conserve water, and produce urine.
What is Chronic Kidney Disease (CKD)?
Many believe that 'chronic kidney failure' means the kidneys stop working entirely and can't produce urine. This isn't true. Chronic renal failure (CRF), or CKD, means the kidneys can't efficiently filter waste from the blood, not that they stop producing urine. Ironically, most dogs with kidney failure produce large amounts of urine, but their bodies can't eliminate toxic wastes effectively.
When Does Chronic Kidney Disease Occur?
Kidney tissue can't regenerate, so at least two-thirds of the kidneys must be dysfunctional before any symptoms appear. Often, this damage has been occurring for months or years before becoming noticeable.
In dogs, CKD is typically associated with ageing. Smaller dogs usually show early signs between ten and fourteen years of age, while larger dogs may develop symptoms as early as seven years of age.
Symptoms of Chronic Kidney Disease
As the kidneys' filtration becomes inefficient, blood flow to the kidneys increases, causing more urine production. To prevent dehydration from this increased fluid loss, dogs drink more water. Early signs include increased water consumption and urination, known as compensated renal failure. Advanced CKD symptoms include loss of appetite, lethargy, vomiting, diarrhoea, bad breath, and sometimes mouth ulcers.
Diagnosing Chronic Kidney Failure
Diagnosis involves two primary tests: a complete urinalysis and a blood chemistry analysis.
Urinalysis: Evaluates kidney function. A low urine specific gravity (USpG) can indicate kidney failure. Increased protein in urine (proteinuria) also signals decreased kidney function.
Blood Biochemistry: Measures levels of waste products like blood urea nitrogen (BUN) and creatinine (CREA) to assess kidney function. Levels of other substances like albumin, globulin, potassium, sodium, phosphorus, and calcium, as well as red and white blood cell counts, help determine the extent of failure and guide treatment.
The SDMA test can detect early kidney failure, often before creatinine levels rise, allowing for earlier treatment.
Determining the Degree of Kidney Failure
Your veterinarian may use the IRIS staging system, which considers serum creatinine levels, protein presence in urine, and blood pressure. This helps tailor treatment and monitor progress.
Treating Chronic Kidney Disease
Treatment depends on blood test results and focuses on addressing specific abnormalities. Early diagnosis and aggressive treatment can allow many dogs to live normal lives for months or years.
Initial Treatment Phase
The first phase involves high doses of intravenous fluids to flush out toxins, known as diuresis. This helps damaged kidney cells function again by creating a healthier environment for healing. Proper nutrition and medication to control nausea, vomiting, and diarrhoea are also important.
Possible Outcomes of Initial Treatment
- Kidneys resume functioning and continue for weeks to years.
- Kidneys resume functioning but fail again shortly after treatment stops.
- Kidney function does not return.
Ongoing Management
After initial treatment, the goal is to maintain kidney function as long as possible through:
- Special Diets: Lower in protein, phosphorus, and not acidified to reduce metabolic toxins and kidney workload.
- Phosphate Binders: Medications to prevent phosphate absorption, lowering blood phosphorus levels.
- Home Fluid Therapy: Maintenance fluids to prevent dehydration and flush toxins.
- Therapy for Proteinuria: Medications to reduce kidney pressure and protein loss.
- Parathyroid Regulation: Medications like calcitriol to manage calcium and phosphorus balance.
- Stimulating Red Blood Cell Production: Synthetic hormones to address anaemia caused by kidney failure.
Prognosis
The outlook varies based on the disease stage at diagnosis, response to initial treatment, and follow-up care. Many dogs respond well, enjoying a good quality of life. Treatment is often straightforward and cost-effective, providing significant rewards for pet owners and their faithful companions.
