Systemic inflammatory biomarkers linked to PKD1 mutation and renal morphometrics in cats with polycystic kidney...

Feline polycystic kidney disease (PKD) is the most common inherited renal disorder in cats and is primarily associated with a nonsense mutation in the PKD1 gene. Although ultrasonography and genetic testing are well-established diagnostic tools, little is known about systemic inflammatory changes during the subclinical stages of feline PKD. This study aimed to evaluate the association between inflammatory biomarkers, PKD1 mutation status, and renal morphometric changes in cats with polycystic kidney disease.

This retrospective, single-center observational study included 28 client-owned cats evaluated by renal ultrasonography and PKD1 genotyping. Based on imaging findings and genetic status, cats were classified into three groups: healthy controls without renal cysts or PKD1 mutation, cats with renal cysts and wild-type PKD1, and cats with renal cysts carrying a heterozygous PKD1 mutation. Hematological inflammatory indices, including neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), and platelet-to-lymphocyte ratio (PLR), were calculated from routine blood profiles. Conventional renal biomarkers (creatinine, blood urea nitrogen, and symmetric dimethylarginine) and ultrasonographic renal morphometric parameters were also assessed. Correlations between inflammatory markers, renal measurements, biochemical indices, and genotype were analyzed using Pearson's correlation.

All cats were clinically stable and non-azotemic at the time of evaluation. Conventional renal biomarkers did not differ significantly among groups. However, cats with renal cysts showed stronger associations between inflammatory indices and renal morphometric parameters compared with healthy controls. These correlations were most pronounced in cats harboring a heterozygous PKD1 mutation, where NLR and MLR were positively associated with kidney size and renal biochemical markers despite values remaining within reference ranges. Scottish Fold cats showed a high prevalence of PKD1 heterozygosity. Overall, systemic inflammatory indices demonstrated closer relationships with renal structure and function than traditional renal biomarkers during early disease stages.

Systemic inflammatory activation is detectable in cats with PKD before the onset of azotemia, particularly in those carrying PKD1 mutations. Simple hematological inflammatory ratios may serve as accessible adjunct tools alongside ultrasonography and genetic testing for the early detection and monitoring of feline PKD. Further longitudinal studies are warranted to validate their prognostic utility.