Top 5 nutrients in managing renal disease
Nutrition plays a crucial role in managing renal disease in canine and feline patients. Available therapeutic diets formulated specifically for the management of renal disease may not be the best choice for every patient at every stage. When choosing the most appropriate diet, it is important to treat each patient as an individual, and to make recommendations based on the specific case. Here are the top five nutritional considerations for renal disease patients:
1) Protein
Protein is one of the most important aspects of renal disease nutritional management. As the nephrons lose their ability to filter protein molecules, more protein can become lost in the urine. Protein levels are also related to controlling clinical signs of uremia (e.g., nausea, vomiting). It is important to provide pets with adequate protein levels until it is necessary to reduce it, normally in IRIS stages 3-4. The idea is to provide optimal amounts of protein to prevent the body from breaking down its own tissue for energy. Patients require appropriate levels of high quality, highly digestible protein to maintain muscle mass. Protein levels may also affect the palatability of the diet, so it is important to ensure patients are eating at their energy requirement to prevent muscle loss. Depending on the stage of renal disease, protein level recommendations can vary, and the requirements for dogs can range between 11-17% protein calories and 20-29% protein calories for cats.
2) Phosphorus
With reduced filtration ability, hyperphosphatemia can occur and is damaging to the remaining functional nephrons, causing progression of disease. Ideally, the phosphorus level needs to be normalized either through diet or supplementation with a phosphate binder. It is very important to feed a lower phosphorus diet based on clinical signs and evidence from laboratory work. It can even be considered in the earlier stages as a method to slow progression. Protein and phosphorus are related; as you reduce protein levels you will reduce the phosphorus levels. Even when a therapeutic renal diet is not yet warranted, other diets like joint support or senior diets, if lower in phosphorus, may be beneficial to these patients. When looking on an energy basis, try to stay within these ranges: 0.2 to 1.07 g/Mcal in foods for dogs and 0.43 to 1.4 g/Mcal in foods for cats.
3) Water
Renal disease puts the patient in a polydipsic and polyuric state, so maintaining hydration can become a challenge. To increase their water intake you can consider feeding a diet that is 70-85% moisture (e.g. pouches, cans, trays, etc.), increasing the availability of water bowls, feeding more frequently (dogs and cats will often drink after eating), and by providing a variety of sources of water that are pleasing to them (fountains, wider bowls, taps, etc.). If their hydration cannot be maintained through voluntary oral intake of water then subcutaneous fluid administration may be needed. This procedure can easily be shown to clients so they can do it at home and this is generally well tolerated by dogs and cats.
4) Potassium
Hypokalemia is more commonly seen than hyperkalemia, especially in feline patients, and it is important to monitor. Hypokalemia can be caused by vomiting, inappetance, polyuria, and metabolic acidosis, leading to weakness and inappetance. If a pet requires supplementation, then find a palatable product and continue to monitor. Selecting a diet with 0.72 to 2.46 g/Mcal potassium for dogs and 1.47 to 3.37 g/Mcal in foods for cats is a great starting point.
5) Energy
Each client should receive a calculated daily calorie requirement and feeding recommendation for their pet. You can use the equation 70 x BW(body weight in kilograms)^0.75 to figure out their resting energy requirement as a starting point, and increase as needed for that individual. It is crucial for patients to maintain their ideal body condition, as inadequate energy intake will cause endogenous protein breakdown, which worsens the disease and can increase their clinical signs.
Other nutrients of importance are sodium and long-chain omega-3 fatty acids. Since hypertension is common in renal disease, diets with a moderately lowered sodium content are recommended as they may help reduce complications with treatment. Long-chain omega-3 fatty acids like EPA and DHA can increase glomerular filtration rate, reduce proteinuria, and decrease inflammation. The best source of long-chain omega-3 fatty acids is coldwater fish oils.
Summary
A patient diagnosed with any stage of renal disease should have a full nutritional assessment done, which includes a diet history, body and muscle condition score, and current body weight. With the guidance of the veterinarian, technicians can help clients find the most appropriate diet and diet form (dry, canned, homemade) for each patient. There are a number of other beneficial nutrients to consider, but if you start with the above then you are on the right path to making the best recommendations for your patients. With regular follow-up calls and in clinic progress exams, appetite, body condition and body weight can be monitored and interventions made as needed. This may include changing the dietary formula, form, or addition of medications or supplements. If the pet has a poor appetite, the client has difficulty giving medications, or the patient is not tolerating subcutaneous fluid administration, then placement of a feeding tube may be warranted. An esophagostomy or gastrostomy tube can be highly effective in maintaining a good quality of life for renal disease patients. This way all fluids, medications, and appropriate diets can be given with minimal stress to the patient. The treatment of renal disease requires a multi-modal approach with nutrition being front and centre. It is ideal to base all recommendations on the individual case, keeping both the client and the patient in mind.
Kelly Gredner is one of 14 members of the Academy of Veterinary Nutrition Technicians (AVNT), a NAVTA approved and AVMA recognized body that certifies Veterinary Technician Specialists (VTS). She is an independent consultant for Balance IT®, helping veterinary clinics further integrate nutrition into clinical practice, along with working in a small animal hospital. Kelly lives in Toronto, Ontario and is a self proclaimed cat lady.CVT
