Page 753 - Small Animal Clinical Nutrition 5th Edition

Chronic Kidney Disease 781

nephritis and glomerulosclerosis apparently are common and
Table 37-9. Key nutritional factors for dogs and cats with
VetBooks.ir It is possible that CKD occurs as a consequence of life-pre- chronic kidney disease.*
occur with increased frequency in aging dogs.
Factors
serving adaptive mechanisms that accompany the aging process
Water Dietary recommendations
Parenteral fluid therapy if dehydration,
(Lawler et al,2006).A study of postmortem data collected from
blood volume contraction or renal
1979 to 2001 revealed that of 676 cats living in a research hypoperfusion is clinically significant
colony, cats that died from kidney disease most often had renal Offer water free choice at all times
Recommend moist foods
histologic changes (i.e., progressive tubular deletion and per-
Protein 14 to 20% in foods for dogs
itubular interstitial fibrosis); however, their mean lifespan was 28 to 35% in foods for cats
longer than cats that died from other causes (Lawler et al, Phosphorus 0.2 to 0.5% in foods for dogs
0.3 to 0.6% in foods for cats
2006). In addition, among cats that died from causes other than
Sodium ≤0.3% in foods for dogs
kidney disease, those with renal histologic changes had a longer ≤0.4% in foods for cats
mean lifespan compared with cats that had no changes in their Chloride 1.5 x sodium levels in foods for dogs
1.5 x sodium levels in foods for cats
kidneys. It was hypothesized that these renal changes may rep-
Potassium 0.4 to 0.8% in foods for dogs
resent an intrinsic mechanism that is protective until the point 0.7 to 1.2% in foods for cats
of failure. Regardless of the initiating cause, CKD often is char- If patient becomes hyperkalemic, switch
to a lower potassium food
acterized by irreversible loss of renal functional mass. After a
Omega-3 fatty acids 0.4 to 2.5% in foods for dogs and cats
critical amount of kidney damage occurs, CKD tends to be a Omega-6:omega-3 fatty acid ratio of 1:1
progressive condition that often terminates with uremia-asso- to 7:1
Antioxidants
ciated death.
Vitamin E ≥400 IU vitamin E/kg of food for dogs
≥500 IU vitamin E/kg of food for cats
Key Nutritional Factors Vitamin C ≥100 mg vitamin C/kg of food for dogs
100 to 200 mg vitamin C/kg of food for
The goals of managing patients with CKD are to: 1) control
cats
clinical signs of uremia, 2) minimize disturbances associated *All values expressed on a dry matter basis, unless otherwise
with fluid, electrolyte and acid-base balance, 3) support ade- indicated.
quate nutrition and 4) modify progression of CKD (Polzin et
al, 2005). Nutritional management plays a role in all of these
goals and is indicated to address the etiopathogenic mecha- fat, omega-3 fatty acids and buffering capacity. Feline renal
nisms that occur in CKD (Table 37-8). In addition, the use of foods contain increased potassium to help prevent hypokal-
an appropriately formulated commercial veterinary therapeutic emia. In addition to key nutritional factors, it is important to
renal food is the only treatment that has been shown in ran- consider available evidence supporting effectiveness of specific
domized, controlled clinical studies to prolong survival time veterinary therapeutic renal foods and other treatments for
and improve quality of life in dogs and cats with CKD (Polzin CKD (Table 37-10). Finally, individual patient needs and
et al, 2009; Roudebush et al, 2009; Jacob et al, 2002, 2004; Ross responses and owner preferences must be considered to design
et al, 2006). Therefore, nutritional intervention should be con- an optimal therapeutic regimen.
sidered a critical component of managing patients with CKD.
When designing a therapeutic regimen for dogs and cats Water
with CKD, it is helpful to consider a food’s key nutritional fac- Kidney disease causes a progressive decline in urine concentrat-
tors. Recommended ranges of these key nutritional factors were ing ability, and maximal urine osmolality approaches that of
determined by considering nutrient levels in foods evaluated in plasma (300 mOsm/kg) (i.e., isosthenuria). As CKD progress-
dogs and cats with naturally occurring CKD and experimental- es; these changes may be observed in patients with stage 1
ly induced kidney disease (Table 37-9). Although numerous CKD. If total solute excretion remains normal, but the maximal
studies have been published about dogs and cats regarding the achievable urine osmolality decreases, obligatory water loss
benefits of various combinations of these factors, little work has occurs to eliminate the osmolar load.This obligatory water loss
been done to isolate effects of individual nutrients (Adams et al, may lead to development of polyuria. Compensatory polydip-
1993; Barber et al, 1999; Bovee, 1991; Brown et al, 1991, 1998, sia occurs to maintain fluid balance. Dehydration, volume
2000; Burkholder, 2000; Burkholder et al, 2004; Elliott et al, depletion, renal hypoperfusion and dietary salt (sodium) intake
2000; Finco et al, 1985, 1992, 1992a, 1998; Jacob et al, 2002; stimulate urine concentration. Concentrating urine solutes rep-
McCarthy et al, 2001; Polzin et al, 1982, 1983, 1983a, 1984, resents “osmotic work” for the kidneys and represents a burden
1991, 1991a, 2000; Robertson et al, 1986; Ross et al, 1982, for diseased kidneys. Reducing the amount of solutes to be con-
2006; Valli et al, 1991). Commercially available veterinary ther- centrated by decreasing dietary protein and sodium intake or by
apeutic foods for dogs and cats with CKD are usually designed providing more water for the excretion of the same amount of
with these key nutritional factors in mind. Compared with typ- solutes independently reduces the amount of osmotic work.
ical maintenance pet foods, appropriately formulated veterinary Patients with CKD should have unlimited access to fresh water
therapeutic foods for dogs and cats with CKD generally con- for free-choice consumption. If readily consumed by the pa-
tain less protein, phosphorus and sodium and have increased tient, moist foods are preferred because their consumption gen-