As a pet owner, at one point or another you have likely heard of “chronic kidney disease”, also referred to as “renal insufficiency”. Renal insufficiency is the most common disease affecting the kidneys of dogs and cats, and unfortunately, is also a common cause of illness and death in pets.
The kidneys are responsible for numerous functions, such as filtering blood, regulating blood pressure, maintaining pH and excreting waste in the urine. Renal insufficiency is irreversible damage to the kidneys, resulting in a gradual loss of kidney function. It most often occurs in older pets, however it can affect animals of any age. A 70% or greater loss in kidney function is typically required before pets start to exhibit any symptoms of the disease. This is because of the kidney’s incredible ability to compensate for any functional tissue loss or damage.
Common signs of renal insufficiency include increased thirst and urination, diarrhea, vomiting, lack of appetite and reduced energy. The initial damage or injury to the kidneys leading to chronic disease is often unknown, as the underlying cause is usually no longer present by the time the disease is diagnosed. However, potential causes include infection, trauma, decreased blood flow to the kidneys, and exposure to toxins.
What happens after your pet has been diagnosed with chronic kidney disease? Unfortunately, the disease is irreversible and there is no cure. However, the good news is that it can be well-managed through diet and medication. Nutritional therapy is considered a key component in managing dogs and cats with chronic kidney disease. Numerous studies have shown an improvement in the quality of life and an increased life span in pets being fed a diet formulated to manage renal disease. The goals of nutritional intervention are to meet the animal’s energy and nutrient requirements, while mitigating clinical symptoms and slowing progression of the disease.
Diets suitable for pets with renal insufficiency are available commercially or a homemade diet formulated by a qualified veterinary nutritionist may be used. Compared to adult maintenance recipes, diets formulated for the management of renal disease typically contain less protein and phosphorus, whilst having an increased level of omega-3 fatty acids.
When protein is consumed in excess of the body’s requirements, it is broken down into nitrogen-containing compounds and filtered out as waste in the urine. Many of the clinical signs of later stage renal insufficiency, such as vomiting and lack of appetite, result from a build-up of these end products. Feeding a diet that is restricted in protein allows the kidneys to work less and prevents an accumulation of these waste products. Similarly, high quality protein ingredients that provide all essential amino acids in the amounts pets require is recommended to help reduce the quantity of waste that the kidneys must eliminate.
However, it is important that pets receive the protein and calories that their body requires. In the early stages of renal insufficiency, a higher protein diet may be recommended, particularly for cats, to prevent muscle loss and malnutrition. If the intake of calories or protein is not high enough, protein in the body will be broken down and will produce nitrogenous waste products. As a result, an important goal of nutritional therapy and managing chronic kidney disease is to provide the right balance of protein and calories depending on the pet’s severity of disease and their symptoms.
When the kidneys become damaged, their ability to filter excess minerals into the urine decreases. This results in a higher level of phosphorus in the blood, which may lead to the formation of crystals in the kidneys, causing further damage and progression of the disease. Additional consequences arising from an increased phosphorus concentration in the blood include bone loss and vitamin D deficiency.
Diets suitable for renal insufficiency are generally formulated with a lower level of phosphorus to help slow disease progression, improve disease management and increase lifespan. Since foods high in protein are often significant sources of phosphorus, restricting protein and choosing low phosphorus ingredients is generally recommended in diets used to treat late stage renal insufficiency.
As previously mentioned, it is important to provide the cat or dog with enough calories, whilst providing a restricted level of protein. As such, fat is added to diets for kidney disease to provide pets with a concentrated source of energy and make the food more appealing. Often omega-3 fatty acids, such as those found in flaxseed, salmon oil and algae extract, are preferred due to their anti-inflammatory benefits and potential to slow disease progression.
Last but not least, it is important to regularly consult with a veterinarian about the right diet for your pet if they have been diagnosed with renal insufficiency. Since the disease can change and progress with time, frequent re-checks are important. Once a diet has been selected, it is vital that you regularly monitor your pet to make sure they are getting optimal nutrition and symptom management.
Thank you to Alexandra Rankovic, Graduate Student at the University of Guelph, for her contributions to writing this article.
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