Renal disease Flashcards
Clinical signs of renal disease
lethargy, inappetence, vomiting/diarrhea, weight loss, pu/pd, poor hair coat (from not eating well), nocturia (accident in the middle of the night)
Suspect renal proteinuria when the UPC ratio is
> 0.4
Nutritional management goals with renal disease
- prevent anorexia and body weight loss
- maintain an adequate glomerular filtration rate
- limit the production of uremic toxins
- avoid protein malnutrition
- prevent development of secondary hyperparathyroidism (occurs as result of kidney’s inability to excrete P, not Ca:P ratio)
When to initiate nutritional management?
Dogs: stages 3-4
Cats: stages 2-4
- when serum creatinine >2 mg/dL
Key nutritional factor: water
- REHYDRATE!
- encourage water intake: provide water free choice, water flavoring, add water into dry diet, feed canned diet
- provide enteral and if needed parenteral fluids
Key nutritional factor: protein
- it is less cleat in dogs and cats if restriction truly slows progression, but we do know that proteinuria leads to renal tubule injury
- protein restriction = decreased morbidity (decreased: azotemia, uremia, hyperphosphatemia, acidosis)
- avoid excessive protein restriction ( dogs: 12-18%, cats: 27-30%); can lead to protein malnutrition -> loss of muscle mass, hypoalbuminemia, anemia, weight loss (muscle and body fat), dull hair coat
Calories and protein relationship
- caloric deficit leads to negative energy balance which leads to body protein catabolism which produces nitrogenous end products (BUN) which can be just as damaging as high protein diet
- positive energy balance = decreased uremia
- fat has more kcal/g than CHO
Key nutritional factor: Energy
- energy prevents protein catabolism and azotemia
- maximize energy from non-protein sources (fat- 1g = 8.5 kcal, CHO- 1g = 3.5 kcal)
- fat (30-60% energy from fat); palatable, increased food energy density, smaller meal to meet daily cal, minimizes gastric distention
Key nutritional factor: phosphorus
- decreasing it slows progression of renal dz in dogs, prolongs survival rate in dogs, less severe renal lesions in cats
- goal: normalize serum P concentration in hyperphosphatemic patients
1. restricted dietary P intake: dogs- 0.15-0.3% DM, cats- 0.4-0.6% DM)
2. if not accomplished by food alone within 2-4 wks add phosphate binders with food - P restriction- prior onset of hyperphosphatemia
Key nutritional factor: NaCl
- retention: increased extracellular fluid volume, hypertension (b/c of reduced renal function), risk of uremic crisis and death
- deficit: decreased extracellular fluid volume, decreased plasma volume, decreased GFR, azotemia
- so balance is very important
- dogs: 0.1-0.25%, cats: 0.2-0.35%)
Key nutritional factor: Potassium
- hyperkalemia: decrease dietary K to 0.3-0.5% DMB
- hypokalemia (cats): increase dietary K to 0.75-1% DMB, oral supplementation, K gluconate
Acid base balance
- metabolic acidosis: decreased H+ excretion and HCO3- re-absorption; acid from sulfur containing amino acids (Met, Cys); acid from endogenous protein during catabolism (low energy/protein intake)
- results in catabolism of muscle protein, dissolution of bone minerals, renal osteodystrophy
Correcting metabolic acidosis
- restrict dietary protein (animal proteins are acidifying)
- promote positive energy balance
- if unsuccessful within 2-4 wks start alkali therapy: Na bicarbonate, Ca carbonate, potassium citrate (if not elevated already)
Key nutritional factor: omega 3 fatty acid
- fish oils- source of EPA and DHA (not flaxseed oil)
- reduces inflammation (in all organs)
- lowers systemic blood pressure
- preserves renal function, decreases proteinuria
- recommended n-6:n-3 ratio- dogs <7:1
Key nutritional factor: fermentible fiber
- “nitrogen trap”
- fiber is substrate for GI bacteria
- urea is source of nitrogen for gut microbe growth
