Updated: Jun 28, 2022
What do my dog's kidneys do? Although they have other functions, the kidneys primarily act to remove waste products from the bloodstream. By doing so they regulate the levels of certain essential minerals such as potassium and sodium, conserve water, and ultimately produce urine.
What is chronic renal failure/chronic kidney disease and what are the clinical signs? This is when - through disease or old age - the kidneys become unable to efficiently filter waste products from the blood. Pets affected by this may begin to produce larger volumes of urine because their bodies attempt to compensate by increasing the blood flow through the kidneys. As more urine is being produced, the animal will therefore usually experience greater thirst and consume more water than usual. These are the early signs of what is termed compensated renal failure. When approximately ⅔ of the kidney tissue is destroyed we see signs of more advanced kidney failure due to the rapid rise of waste products in the bloodstream. These include loss of appetite, depression, vomiting, diarrhoea, mouth ulcers and bad breath.
Which dogs suffer from chronic kidney disease?
Kidney tissue cannot regenerate if destroyed, so the kidneys therefore have a large amount of reserve capacity to perform their various functions. At least ⅔ of the kidneys must be dysfunctional before any clinical signs are seen, meaning that in many cases the destruction has been occurring for months to years (chronic) before failure is evident.
In dogs, chronic kidney disease can occur as a result of ageing and the age of onset is often related to the dog’s size: for most small dogs the early signs of kidney disease occur at around ten to fourteen years of age. However, large dogs have a shorter lifespan and may experience kidney failure as early as seven years of age.
How is chronic kidney failure diagnosed?
Urine and blood tests are both important in diagnosing renal failure. Commonly, increases in blood levels of urea, creatinine and SDMA are used in combination with a dilute urine to confirm kidney dysfunction. Veterinarians determine the degree of kidney failure using the IRIS (International Renal Interest Society) system to decide what ‘stage’ a dog’s renal failure is at. IRIS staging takes blood test results and other symptoms (such as blood pressure or the amount of protein in the urine) into consideration. A dog can be diagnosed with IRIS Stage 1 (least severe) to IRIS Stage 4 (most severe).
How is chronic renal disease treated?
The type of treatment required for chronic kidney disease depends on the underlying cause, results of blood tests, and the symptoms that your pet is showing. In some cases where pets feel very unwell or have high levels of waste products in the body, hospitalisation and fluid therapy/medical treatment will be required.
For dogs that are stable at home, treatment then focuses on providing measures to help manage the disease and slow the ongoing kidney damage.
How can diet help manage renal failure
Correct nutritional management of pets with renal failure is vital: it helps to improve quality of life and slow the progression of the disease.
With early diagnosis and proper dietary management many pets can live normal lives for several years. Veterinary research has shown that adjustments in particular nutrients can increase the ‘lifespan’ of the remaining kidney tissue and help to reduce symptoms like nausea and vomiting.
Phosphorus reduction
Because the kidney filtration system is not working properly, pets with renal disease usually develop high levels of phosphorus in their blood. As well as causing further damage to the kidneys, high phosphorus may also contribute to feelings of nausea. Lowering the phosphorus level in the blood of pets with renal failure appears to have a protective effect on the kidneys, slowing progression of the disease, and may reduce nausea. The level of phosphorus restriction required will depend on your dog’s renal disease stage and blood phosphorus level. Veterinary guidelines recommend a level of between 0.2% and 0.5% Dry Matter.
Most meats and protein sources are higher in phosphorus, whilst most vegetables and simple carbohydrates are lower. This means that recipes designed for renal disease tend to include higher levels of carbohydrates and less meat.
VetChef recipes are formulated to meet clinically recommended phosphorus levels for renal failure. There are lots of VetChef Renal recipes available to Clinical subscribers, and we can help you choose recipes based on recent blood results and your own vet’s recommendation.
Commercially available pet foods designed for renal failure also contain limited phosphorus levels. If you are using a combination of the two, the Vetchef dashboard can help you to keep track of your dogs’ average phosphorus intake - your vet will need this information to help interpret your next set of blood results.
In later-stage disease, phosphorus levels may remain high despite very low intakes. In these cases, it’s not uncommon that your vet might recommend the use of a ‘phosphate binder’ in food if the blood phosphorus is not being adequately controlled by the diet. These medications are usually liquids and are made to bind up the phosphorus in the food, thus preventing your dog from absorbing it.
If your dog has kidney disease, a VetChef Clinical plan will provide Prescription Homemade recipes and supplements, plus expert support from our team of clinical nutritionists.
Other dietary adjustments in renal failure:
B Vitamins Pets with renal disease often drink and urinate more than usual. B vitamins are water soluble and this increased water loss can often mean that they are ‘washed out’ more quickly than usual. The VetChef recipes and Supplement (K951) are designed to provide higher B vitamin levels, preventing complications associated with B vitamin deficiency such as poor appetite and some types of anaemia. Protein alterations In order to reduce phosphorus intake for pets with renal disease it is common to reduce the dietary protein levels. The level of protein restriction may also become more crucial in later-stage disease. Many of the waste products that can build up in the blood of dogs with renal failure are derived from protein-rich foods. This means that reducing protein plays a role in reducing feelings of nausea, especially in pets with IRIS Stage 3 or 4 disease.
It is important to strike the right balance with protein restriction. Pets with later-stage disease and nausea may benefit from lowered protein levels (20% DM or less), but those with early-stage disease, or those that are still very active/not eating enough may still need protein levels that are a little higher to prevent muscle wastage.
Omega 3 There is a raft of evidence that increasing the levels of specific types of omega 3 fatty acids (EPA and DHA) can have anti-inflammatory effects on the tiny filters in the kidney (the glomeruli). EPA and DHA levels are high in fish oils and formulations from VetChef include increased levels of these fatty acids.
Antioxidants All chemical reactions in the body produce reactive ‘waste’ particles called ‘free radicals’ that have the potential to damage nearby cells. In normal pets these are neutralized by internal antioxidants, but in pets where levels of inflammation are higher, the number of free radicals are increased and can exceed the body’s ability to neutralise them all.
Increasing antioxidants can help to combat this by neutralizing as many free radicals as possible before they cause further damage to the kidney. These antioxidants include vitamins E and C as well as plant-based antioxidants like betacarotene or lycopene from fruit and vegetables.
Sodium Restriction The failure to correctly filter out sodium means that pets with renal failure have a tendency to retain sodium/salt. This can contribute to high blood pressure, which in turn causes further damage to the kidney tissue.
The sodium level in recipes for pets with renal disease should be less than 0.3% by dry matter. If your pet has been on normal dog food (of any kind including tins/kibble/raw or cooked) until recently, it’s important to introduce a low sodium diet gradually (over a few weeks) so that their body can adjust to the change.
It’s also important to remember that ‘low salt’ is not the same as ‘NO salt’. Salt (sodium and chloride) are vital for normal body function. You will notice that some of our recipes do include table salt - this is because the low-meat nature of the recipes need a little salt to be added to meet your dogs’ minimum requirements. Please do not remove this: our recipes are accurately calculated to make sure the overall salt level remains low.
Water! We must never underestimate the importance of water. Pets with renal disease cannot conserve water as well as normal dogs. This means they are more vulnerable to dehydration if they become unwell for any other reason, or sometimes even if the weather is hot. Dehydration causes headaches and nausea so ensuring your pet takes plenty of water on board is vital. Wherever possible, feeding wet foods (like tins or home-cooked meals) is helpful - or add plenty of water if you are using dry commercial prescription diets.
Medical management of renal failure
Your vet may discuss some different types of medication with you. These are aimed at improving some of the clinical signs:
Blood pressure management The kidneys play a role in the management of blood pressure, so pets with later-stage renal disease often have high blood pressure. It’s important to control this to prevent damaging the remaining kidney nephrons.
Drugs to reduce protein in the urine (proteinuria) Dogs with protein in their urine may need to take Angiotensin Converting Enzyme Inhibitor (ACE inhibitors) to lessen the degree of proteinuria.
Drugs to help correct anaemia The kidneys are responsible for stimulating the production of new red blood cells. This means some dogs develop anaemia in later stages. Replacing the enzyme usually produced by the kidneys (Erythropoeitin) can stimulate your dog to produce more red blood cells.
How long will my dog live?
There are a lot of factors that will determine prognosis. Your vet will be able to discuss this in more detail with you. For some pets the deterioration may be rapid but many dogs with chronic renal disease will live for a few years if they are diagnosed early and managed carefully.
If your dog has kidney disease, a VetChef Clinical plan will provide Prescription Homemade recipes and supplements, plus expert support from our team of clinical nutritionists. Get started with a FREE consultation with our Nutritional Advisors today.