Chronic Kidney Disease: A Critical Look at Urolithiasis in Cats

This artocle shines a spotlight on Chronic Kidney Disease (CKD), a condition increasingly seen in the feline population. Dr. Christelle Maurey, Senior Lecturer at the Ecole Nationale Vétérinaire d'Alfort, has provided a concise summary of a notable study by Huai-hsun Hsu and colleagues, as published in the Journal of Feline Medicine and Surgery in April 2022. This study explores the frequent occurrence of upper urinary tract lithiasis (UUTL) in conjunction with CKD in cats. Furthermore, we delve into the recommendations of the International Renal Interest Society (IRIS) concerning the diagnosis, monitoring, and management of CKD in dogs and cats.

Expert Summary

The study in focus, titled "Upper Urolithiasis in Cats with Chronic Kidney Disease: Prevalence and Investigation of Serum and Urinary Calcium Concentrations," provides critical insights into the prevalence of UUTL among cats with CKD, presenting data from cats at a university hospital. Notably, the study distinguishes between cats with and without urolithiasis by comparing total and ionised plasma calcium levels and the urinary calcium/creatinine ratio (UCa/Cr).

Study Background

UUTL's association with CKD has been rising over the past two decades. Uroliths, when leading to ureteral obstruction, can exacerbate renal failure. Although several studies have highlighted oxalocalcic urolithiasis as the predominant form in felines, few have extensively investigated the epidemiological or biological factors contributing to its development.

Study Objectives

The primary aims of the study were:

  • To establish the prevalence of HAU lithiasis in a cohort of cats with CKD at a university hospital.
  • To compare biochemical markers such as plasma calcium levels and the UCa/Cr ratio between cats with CKD, with and without urolithiasis.

Methodology

The research involved a thorough review of medical records for cats diagnosed with CKD, focusing on their diet, body weight, and presence of uroliths. Cats with available urine samples were divided into two groups for analysis: those with urinary lithiasis and a control group with CKD of unknown origin. Statistical analyses were employed to compare the data.

Findings

The study found a significant prevalence (73%) of HAU lithiasis among cats with CKD. Pedigree cats and those fed a dry diet were identified as having higher risks of developing urolithiasis. Notably, increased plasma ionised calcium levels and higher UCa:Cr ratios were observed in cats with both CKD and urolithiasis, suggesting these factors as potential contributors to stone formation.

Clinical Implications

The results underscore the potential role of dry food in the development of UUTL in cats. Genetic predispositions also warrant further investigation. The findings recommend monitoring ionised calcium levels as they are significantly higher in cats with urolithiasis, potentially contributing to the formation of calcium oxalate stones.

Literature Review and IRIS Recommendations

The IRIS committee provides detailed guidelines on managing CKD, emphasizing early diagnosis and careful management based on disease staging. These guidelines are crucial for optimizing patient care and are available for consultation on the IRIS website.

In conclusion, this study not only highlights the significant relationship between diet, genetics, and CKD with UUTL but also calls for a deeper understanding of the mechanisms behind crystallogenesis in cats. For more detailed insights and to view references, visit the links provided in our references section.

The development of new tests and the identification of the different stages of chronic kidney disease should enable each animal to be given personalised care depending on its stage of development.

References :

  • International Renal interest Society.  IRIS Kidney - Guidelines - IRIS Staging of CKD (iris-kidney.com) (accessed 14 December 2022)
  • International Renal interest Society.  IRIS Kidney - Guidelines - IRIS Treatment Recommendations (iris-kidney.com) (accessed 14 December 2022)
  • International Renal interest Society.  IRIS Kidney - Education - Early Diagnosis (iris-kidney.com) ( accessed February 20th 2023)
  • IRIS Pocket guide to CKD IRIS_Pocket_Guide_to_CKD_2023 (iris-kidney.com) ( accessed February 20th 2023)
  • Hsu HH, Ueno S, Miyakawa H, Ogawa M, Miyagawa Y, Takemura N. Upper urolithiasis in cats with chronic kidney disease: prevalence and investigation of serum and urinary calcium concentrations. J Feline Med Surg. 2022 Jun;24(6):e70-e75. https://pubmed.ncbi.nlm.nih.gov/35471088/ 
  • Miyakawa H, Hsu HH, Ogawa M, Akabane R, Miyagawa Y, Takemura N. Association between serum fibroblast growth factor-23 concentration and development of hyperphosphatemia in normophosphatemic dogs with chronic kidney disease. J Vet Intern Med. 2021 Sep;35(5):2296-2305. https://pubmed.ncbi.nlm.nih.gov/34418162/ 
  • Miyakawa H, Hsu HH, Ogawa M, Akabane R, Miyagawa Y, Takemura N. Serum fibroblast growth factor-23 concentrations in young and mature adult cats with chronic kidney disease. J Feline Med Surg. 2022 Aug;24(8):815-820. https://pubmed.ncbi.nlm.nih.gov/34431737/