NUTRITION
Renal diets are restricted in protein, phosphorus and
sodium and supplemented with potassium, omega-3
fatty acids, B vitamins and fat content, and are alkalinising. It is unknown which alterations are responsible
for survival benefits, although studies in experimental
models support phosphate restriction and essential
fatty acid (EFA) supplementation as potential mechanisms.2
cats did not show a slow progressive increase in creatinine over the 24 months of the study, but rather
developed acute uraemic crises (6/45 cats). All 6 affected cats were in the maintenance diet group rather
than the renal diet group. Only 3 cats survived the
uraemic episode and the increased creatinine levels
were sustained after the crisis.3
Of all the CKD treatments used to date, dietary modification has the most positive long-term effect on outcome.2 Additionally, a randomised, controlled, clinical
trial (RCCT) compared feeding maintenance diets
with renal diets in spontaneous CKD stages 2 and 3.
Cats fed the renal diet developed fewer uraemic episodes (0% versus 23%) and none died from renal disease. 2 See Figure 1 for IRIS staging overview.
There is no evidence supporting dietary modification
in stage 1 CKD, although, in the authors’ experience,
introducing a dietary change in a clinically well cat improves diet acceptance.2 Over 90% of cats with CKD
accepted renal diets when a very gradual transition
was used. Attempting changes in sick, hospitalised,
anxious patients can result in food aversion. Dietary
modification should not be attempted until patients
are well and discharged from hospital. There will always be some cats defiant of diet change.
Criteria for the timing of initiation of dietary modification have been empirical. It is generally accepted that
uraemic patients will benefit from protein and phosphate restriction.3 Results of a study by Ross (2006),
where 45 cats were divided into 2 grouped and fed either maintenance diet, or a renal diet, show that there
is a benefit to dietary modification in the management
of stage 2-3 CKD.3 The study also found that affected
Although home-prepared renal diets are attractive to
some owners, dietary assessment identified numerous nutritional inadequacies.2 Therefore, in cats refusing renal diets, use of senior diets with phosphate
binding agents (PBAs) if hyperphosphataemia is present, while not ideal, may be better than provision of
maintenance diets alone.2
Staging
IRIS
stage
sCreat
(μmol/l)
sCreat
(mg/dl)
1
<140
<1.6
2
140–
250
1.6–2.8
3
251–
440
2.9–5
4
>440
>5
Substage: UPC
<0.2
Non-proteinuric
0.2–0.4
Borderline
proteinuric
Re-evaluate
within 2
months
Substage: SBP
>0.4
Proteinuric
Repeat within
2 weeks
(except if
UPC >2)
Substage
SBP
Risk of
(mmHg) TOD
0
0 <150
1
150–159 Low
2*
160–179
Moderate
3**
180
High
Minimal
The CKD stage is based on serum creatinine concentration, assessed on at least two occasions, and further substaging
is based on proteinuria, assessed by UPC and blood pressure measurement. Only stable patients can be staged and
blood should be drawn after a 12 hour fast, where access to drinking water is allowed
Figure 1: IRIS Staging Overview.
References available on www.vet360.vetlink.co.za
Issue 01 | FEBRUARY 2016 | 19
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