Page 738 - Small Animal Clinical Nutrition 5th Edition

766 Small Animal Clinical Nutrition

VetBooks.ir Table 37-1. International Renal Interest Society (IRIS) Staging System for Chronic Kidney Disease in Dogs and Cats.
Serum
Substage based on
Serum
Stage
<1.4 mg/dl
Non-azotemic CKD
Proteinuria: NP/BP/P*
1 creatinine (dogs) creatinine (cats) proteinuria and hypertension Comments
<1.6 mg/dl
(<125 µmol/l) (<140 µmol/l) Hypertension: N/L/M/H/nc/c/RND** Clinical signs (other than PU/PD)
usually absent
2 1.4-2.0 mg/dl 1.6-2.8 mg/dl Proteinuria: NP/BP/P* Mild renal azotemia
(125-179 µmol/l) (140-249 µmol/l) Hypertension: N/L/M/H/nc/c/RND** (overlaps with reference range)
Clinical signs (other than PU/PD)
usually mild or absent
3 2.1-5.0 mg/dl 2.9-5.0 mg/dl Proteinuria: NP/BP/P* Moderate renal azotemia
(180-439 µmol/l) (250-439 µmol/l) Hypertension: N/L/M/H/nc/c/RND** Extrarenal clinical signs usually begin
in this stage
4 >5.0 mg/dl >5.0 mg/dl Proteinuria: NP/BP/P* Severe renal azotemia
(>440 µmol/l) (>440 µmol/l) Hypertension: N/L/M/H/nc/c/RND** Many extrarenal clinical signs usually
present
Key: PU/PD = polyuria/polydipsia, UPC = urine protein-creatinine ratio, BP = blood pressure.
*NP = non-proteinuric (UPC <0.2), BP = borderline proteinuric (UPC = 0.2 to 0.4 in cats and 0.2 to 0.5 in dogs), P = proteinuric (UPC >0.4
in cats and >0.5 in dogs).
**N = minimal risk of complications (systolic BP <150 mm Hg), L = low risk of complications (systolic BP 150 to 159 mm Hg),
M = moderate risk of complications (systolic BP 160 to 179 mm Hg), H = high risk of complications (systolic BP >180 mm Hg),
nc = no evidence of hypertensive complications, c = hypertensive complications present, RND = risk not determined (blood pressure
not measured).
Adapted from www.iris-kidney.com.

even in the absence of azotemia, reflects marked renal damage parison, 39 of the 325 died of feline leukemia and 45 died due
and signals the need for nutritional management regardless of to other causes.
the CKD stage.
Relationship Between Age and Kidney Disease
CKD occurs in dogs and cats of all ages, but it is frequently a
CLINICAL IMPORTANCE disease of older pets. In a retrospective study of 70 cats with
CKD, diagnosed from 1973 to 1984, ages ranged from nine
Prevalence of Chronic Kidney Disease months to 22 years (mean, 9.2 ± 5.5 years). Nine cats (12.8%)
CKD is a common cause of morbidity and mortality in dogs were less than three years old, 24 (34.3%) were four to seven
and cats. In a survey of 1,600 pet dogs over five years of age years old and 37 (52.9%) were more than seven years old
examined at a European veterinary college for a variety of rea- (DiBartola et al, 1987). In a study of 175 cats diagnosed with
sons, approximately 20% had abnormally increased markers of CKD in Australia from 2000 to 2003, ages ranged from two to
renal function. It is not known how many of these dogs had 21 years (mean, 13.2 ± 3.7 years). However, the majority (69%)
kidney disease (Leibetseder and Neufeld, 1991). In a cross- were 12 to 18 years old (White et al, 2006). The mean age for
sectional study of 31,484 dogs and 15,226 cats evaluated in cats diagnosed with CKD at the Animal Medical Center in
private practices across the United States in 1995, the preva- New York from 2000 to 2002 was 12.8 ± 4.4 years (Boyd et al,
lence of kidney disease was 2.2% in cats and 0.8% in dogs 2008). Analysis of data from university teaching hospitals con-
(Kirk et al, 2001). During 1990, the diagnosis of CKD in cats tributed to the Veterinary Medical Data Base from 1980 to
of all ages reported to the Veterinary Medical Data Base was 1990 indicated that 37% of cats with CKD were less than 10
16 cases/1,000 cats examined. By 2000, diagnosis of CKD in years old, 31% of cats were between 10 and 15 years old and
cats of all ages was 96 cases/1,000 cats examined (Ross et al, 32% of cats were older than 15 years (Lulich et al, 1992). In a
2006). Increased diagnosis of CKD in cats may be due to their 1995 survey of private practices, the mean ages of dogs and cats
living longer, more of them being screened for CKD and/or with kidney disease were 10.2 and 13.2 years, respectively (Kirk
increased awareness of CKD by veterinarians. CKD appears et al, 2001). Another study in dogs showed a similar relation-
to be a common cause of death in dogs and cats. In a retro- ship between aging and occurrence of CKD. Prevalence of
spective study of dogs, 2% died from chronic nephritis, 2% CKD was reported to be nine cases/1,000 dogs of all ages
from pyelonephritis and 1% from glomerulonephritis (Bron- examined, 12.5 cases/1,000 in dogs between seven and 10 years
son, 1982). Thus, the overall mortality from kidney diseases old, 24 cases/1,000 in dogs between 10 and 15 years old and 57
was 5%. With the exception of cancer, kidney disease was the cases/1,000 in dogs over 15 years old (Polzin et al, 1995).
most common cause of death in this study. In a 1991 survey
by the Morris Animal Foundation of readers of Companion Causes of Kidney Disease
Animal News, respondents indicated that of 325 cats that had Familial Kidney Diseases
died, 94 succumbed to kidney disease (MAF, 1991). By com- Juvenile kidney disease increases suspicion of a familial