The kidneys are the organs that eliminate waste products from food and normal bodily processes that would otherwise accumulate in the blood and result in toxic build up. The kidneys are made up of tube-like structures (nephrons) and inside each nephron is a sieve (glomerulus). Kidneys are important in not only removing waste products, but also in controlling other important processes: acidity levels, regulation of minerals, red blood cell production and blood pressure (through production of hormones and enzymes).
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Signs and symptoms of chronic renal failure in dogs
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Dogs with chronic renal failure show signs of increased thirst and urination. They often feel nauseous and may vomit due to toxins building up in their system and this results in a loss of appetite and weight loss.
Diagnosis of chronic renal failure
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The veterinarian will take a history and perform a full examination. Bloods will be taken for a full blood count (checking for anaemia) and a biochemical profile (increased creatinine and BUN or blood urea nitrogen are signs of renal failure). A urinalysis may be performed to assess the urine̵7;s specific gravity as the urine becomes less concentrated with renal failure. A bacterial culture may be performed to assess for infection. Further investigations such as x-rays, ultrasound scan and biopsies may be performed to determine the cause of the renal failure.
What are ACE inhibitors?
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ACE inhibitors or angiotensin converting enzyme inhibitors prevent the activation of a protein (prevents activation of angiotensin I to angiotensin II). Preventing the activation of angiotensin I stops contraction of cells around the blood vessels meaning the blood vessels remain relaxed and wider.
ACE inhibitors and renal failure
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ACE inhibitors appear to reduce pressure within the kidneys and this prevents the loss of protein which in turn prevents further damage to the kidneys and has been shown to be beneficial in cats with protein in their urine (References 1,2). However it remains unclear if dogs that do not have protein in their urine (proteinuria) have any beneficial effect. The lowered pressure within the kidney caused by the ACE inhibitors can cause an increase in BUN and creatinine levels and should be monitored after starting treatment.
Other treatments
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Treatments are designed to slow the progression or reduce side effects of renal failure. The mainstay of slowing progression is a specialized renal diet reduced in protein and phosphorous and increasing fluids either through drinking or by sub-cutaneous fluid. Other treatments include: phosphate binders, control of anaemia, acidosis, nausea, blood pressure and maintaining other minerals within normal limits.
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