by Dr. Dave Hutsebaut
Chronic kidney disease (CKD) is an irreversible, progressive loss of kidney function and is the most common kidney disease of dogs and cats. CKD is more common in older patients but can affect them at any age. There are many causes of CKD including various congenital and acquired diseases. The kidneys are a complex organ system that act as the body’s filter removing waste from the blood, maintaining fluid balance, and producing hormones that produce red blood cells, promoting bone health, and regulating blood pressure. With CKD, the kidneys lose the ability to function adequately leading to a buildup of waste in the blood, excessive water loss, electrolyte imbalances, and decreased hormone production.
CKD is diagnosed using a combination of clinical history, complete blood count, chemistry panel, and urinalysis. Clinical sign may include increased drinking, increased urination, weight loss, decreased appetite, vomiting, lethargy, diarrhea, weakness, and bad breath. A complete kidney workup may include a urine protein creatinine ration, urine culture, blood pressure, diagnostic imaging (abdominal xray and or ultrasound), and kidney cytology or biopsy.
SDMA or Symmetric Dimethylarginine is a byproduct of protein breakdown and is primarily removed from the blood by the kidneys. The use of SDMA in veterinary medicine is still relatively new however studies have shown it to be a more sensitive and early indicator of CKD. SDMA may be elevated before any other kidney function value so it can be useful in diagnosing early kidney disease. The benefit of early detection is early treatment which can slow the progression of the disease. IDEXX Laboratory has developed a blood test to measure SDMA levels which is included on all blood chemistry panels we send out.
The International Renal Interest Society (IRIS) has created a staging system for CKD based on several parameters of the patient assessment which can assist with managing the patient’s treatment plan. These include blood creatinine level, blood SDMA level, urine protein creatinine ratio, and systolic blood pressure. Based on these parameters, the patient can be staged from 1-4. Stages 1-2 are early stages and treatment goals are to slow the progression of CKD and preserve kidney function longer. Stage 3, clinical signs become more common and severe. By stage 4, treatments are aimed at improving or preserving quality of life. In addition to treatments associated with staging guidelines, concurrent diseases must also be treated. When left untreated, CKD can lead to severe weight loss, severe dehydration, high blood pressure, and death. Visit the IRIS site more information about IRIS staging.