Pets will lose about 75% of their renal function before azotemia is noted on the labwork. This is why staging is important to determine how far underlying renal disease has progressed, so that supportive measures and appropriate intervention can take place.
What is Chronic Kidney Disease?
Chronic renal disease is kidney disease that has been going on for months or years (longer term). This is different than acute renal failure which occurs suddenly and more severe (such as with antifreeze or lily toxicity). There are many possible causes of chronic kidney disease including:
- Chronic bacterial infection
- A defect of the kidneys at birth
- Hypertension (high blood pressure)
- Autoimmune disease (such as lupus, glomerulonephritis, or amyloidosis)
- Infectious diseases (such as Lyme or Ehrlichia)
The kidneys contain thousands of nephrons (the functional unit of the kidney). The kidneys help to filter blood waste (from toxins, foods, cells, etc.), conserve water and electrolytes, and regulate calcium and Vitamin D levels. They also produce erythropoietin which helps the body to make new red blood cells.
Pets can have many symptoms, most commonly including decreased appetite, occasional vomiting, weight loss, and increased drinking and urinating.
Labwork often shows anemia of chronic disease (non-regenerative), elevated BUN and creatinine (azotemia), increased phosphorus, dilute urine, proteinuria.
Staging is helpful to determine severity of the renal failure. The International Renal Interest Society (IRIS) provides a helpful algorithm for staging renal failure in pets. IRIS Kidney Disease Algorithm
Tests to help determine the underlying cause of kidney disease include x-rays or ultrasound (to look at kidney structure and look for kidney stones), a renal biopsy in cases that are suspected autoimmune or congenital, urine culture and MIC, blood pressure, and urine protein:creatinine ratio.
Treatments can include diets limited in protein, phosphorus, and ash, phosphorus binders if the phosphorus is high, weekly (or more frequent) subcutaneous fluids for renal support, antacids (such as famotidine), and others. The treatment plan varies per patient and is tailored to each individual based on lab findings, stage of renal disease, underlying complications (such as hypertension), and clinical status.