Abstract
Chronic kidney disease is one of the most common disorders in dogs and cats. Plasma urea nitrogen (P-UN) and creatinine (P-Cre) concentrations are not sufficiently sensitive for the early diagnosis of renal dysfunction. Although urine and plasma clearance methods allow earlier detection of reductions in the GFR, it is difficult to estimate mildly reduced GFR from the values obtained by these methods, as they are also affected by physiological factors, such as body weight (BW) and age. The present study is a retrospective survey designed to assess the factors that affect markers of kidney function and to revaluate the clinically utility of these markers including P-UN, P-Cre, and GFR determined by plasma iohexol clearance (PCio) in dogs and cats. P-UN, P-Cre, and PCio values in dogs, and P-Cre and PCio in cats were significantly correlated with BW (P<0.001). PCio in smaller dogs (≤15.0 kg) was significantly and inversely correlated with age. In smaller dogs, the increase of P-UN alone might warrant a suspicion of decreased GFR, but in contrast, P-Cre may be inefficient for detecting renal dysfunction or determining the severity of CKD compared with that in larger dogs (≥15.1 kg). P-Cre in larger dogs correlated better with PCio than that in smaller dogs, suggesting that P-Cre in larger dogs was a more sensitive marker of reduced GFR.
