What is kidney disease or kidney failure?
The role of the kidneys is to eliminate toxins from the body by filtering any unwanted substances in the blood. These toxins are often waste products from normal cellular functions that are necessary for the body's daily metabolic processes. Kidney disease or failure in dogs is divided into two types: chronic renal failure (CRF) and acute renal failure (ARF), while any kidney condition that leads to the loss of protein through the urine - such as protein-losing nephropathy (PLN) or a condition that deviates from normal kidney function - can be characterized by the general term nephropathy.
Acute Renal Failure (ARF) is characterized by a sudden suppression of the functional capacity of the kidney and can affect both young and old dogs. The most common causes leading to ARF are multiple and usually involve toxic substances or are the result of emergency situations (e.g. extensive bleeding, burns, poisoning and/or ascending microbial infections, etc.). ARF is a serious and potentially reversible condition that requires immediate medical attention.
Chronic Renal Failure (CRF) is an irreversible loss of kidney function and can begin months or years before symptoms appear. It can occur at all ages but mainly affects older dogs, sometimes as a result of gradual, natural deterioration of the kidneys and sometimes as a result of progressively worsening kidney damage from systemic diseases (e.g. Leishmaniasis, diabetes mellitus, etc.), while it is often accompanied by simultaneous protein loss (PPL).
Nutrition and kidney disease in dogs
In the case of ARF ( Acute Renal Failure) the nutritional approach often aims to address anorexia often exacerbated by coexisting diseases of the intestine, stomach or pancreas. To avoid extensive weight loss during the initial stage of treatment, easily digestible, palatable and low-calorie diets are recommended. For example, a high-quality diet, highly digestible and limited in fat, can help accelerate gastric emptying and reduce nausea. At a later stage, high-calorie diets may prove useful to more quickly cover the caloric needs of the animal under treatment. Recommendations regarding the ideal protein content vary although scientific studies are slowly accumulating against protein restriction in later stages of treatment. The only reason to moderate protein in animals with kidney disease is the coexisting proteinuria for which a significant reduction in protein in the meal (25 - 50%) must be taken to avoid further kidney damage. However, it is important to re-evaluate the nutritional plan of animals with ARF ( Acute Renal Failure) frequently taking into account possible electrolyte disturbances and acid-base balance disorders, combining it with specific medication.
In the case of CKD ( Chronic Renal Insufficiency) the nutritional plan differs from dog to dog and depends on the stage of kidney disease - IRIS system (1 to 4), the presence of coexisting diseases (e.g. pancreatitis) but also the nutritional specificities in the composition of the meal. Indicatively, the most important control parameters in meals for animals with kidney disease are described below:
Proteins: One of the most common challenges we face in CKD ( Chronic Kidney Disease) is the reduced or selective appetite, severe loss of muscle mass and the dog's malaise, which not infrequently leads pet owners to search for alternative, more palatable types of food. According to a recent 2020 study Nutritional and laboratory parameters affect the survival of dogs with chronic kidney disease , there is a direct correlation between the nutritional status of a kidney-affected dog and its life expectancy. Specifically, dogs with increased body weight and muscle coverage had increased survival rates compared to other dogs that showed cachexia and body weight loss. In patients with chronic renal failure, without concomitant severe proteinuria, further protein deprivation in the diet is increasingly controversial, while moderating their concentration is preferred, choosing proteins of high biological value to maintain their body weight.
Phosphorus: The accumulation of phosphorus (P) in the body is one of the most common causes of clinical deterioration of the disease, therefore, one of the goals of the nutritional approach for patients is to reduce P intake with foods that are low in phosphorus, or with substances that bind phosphorus in the gastrointestinal tract during digestion.
Salt (Sodium Chloride): The role of dietary sodium restriction for dogs with CKD ( Chronic Renal Failure) is controversial mainly due to the absence of clear dietary limits on the use of sodium chloride. In special commercial diets for renally impaired animals, values of 2 - 5 times the minimum recommended salt intake for dogs according to the American Feed Safety and Quality Control Authority AAFCO are often chosen. It is known that increased sodium chloride intake contributes to hypertension, nephrotoxicity and the development of proteinuria. On the contrary, there are several studies in dogs and cats that show adverse effects from excessive sodium chloride restriction in the diet of renally impaired dogs, due to the activation of the renin-angiotensin-aldosterone system leading to hypertension, potassium loss through urination and metabolic acidosis.
Calcium: Dogs and cats with CKD ( Chronic Renal Failure) may develop disturbances in calcium homeostasis from parathyroid hormone overactivity in bone. There is a risk of extensive soft tissue calcification when the phosphorus x calcium product exceeds 60 to 70 mg/dL and this condition has been associated with reduced survival in dogs with CKD.
Vitamin D: It is common for dogs with chronic kidney disease to have impaired vitamin D biosynthesis, which is associated with worsening electrolyte disturbances, particularly calcium and phosphorus, and mineral bone disorder (MBD). Adequate dietary vitamin D intake improves calcium homeostasis in dogs by reducing parathyroid hormone overactivity in bone.
Fatty acids: Many pet owners supplement their dogs with kidney disease with various supplements containing omega-3 fatty acids, often in excessive amounts, with the extensive use of these supplements often leading to the intake of unwanted calories. A balanced diet should provide the necessary fatty acids in moderation for the proper functioning of the body. These include omega-3s, especially EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), which have strong anti-inflammatory effects.
In conclusion, regardless of the type of kidney disease that our dog may suffer from, it is important to implement a personalized nutritional plan for its needs each time, in order to ensure its adequate daily nutrition. It is not uncommon for guardians of dogs with kidney disease, to ensure that their dog will eat, to choose to combine a special clinical diet for kidney disease dogs with a complementary palatable and often inappropriate food that acts as an appetite stimulant. The use of petchef's delicious and balanced recipes with its abundance of nutrients, easily digestible proteins of high biological value, vitamins and essential omega-3 fatty acids that make up its recipes, can benefit the chronically ill dog by offering it additional well-being and energy, while strengthening the natural antioxidant processes in its body. In the chronic form of kidney disease, in asymptomatic dogs without proteinuria, who show selective or reduced appetite, we suggest our lowest protein concentration diet (up to 8.7% protein): Chicken with carrot and kale.
Since our recipes are aimed at clinically healthy dogs, we recommend that you combine them with nutritional supplements that enhance kidney function and bind phosphorus in food (e.g. Pronefra, Renalvet, etc.). Taking the above into account, in any case we recommend that you seek the consent of your treating veterinarian before making any decision to feed your kidney-diseased dog with petchef recipes.
Spyrliadis AlexanderAthens Vet -Modern Veterinary Clinics