# Preliminary study investigating the role of estimated glomerular filtration rate, proteinuria and hypertension to inform on chronic kidney disease after acute kidney injury

## TL;DR

This study examines how kidney function in dogs recovers after acute kidney injury and finds that some non-azotaemic dogs still have kidney dysfunction months later.

## Contribution

The study introduces estimated glomerular filtration rate as a potential tool to detect ongoing kidney dysfunction in non-azotaemic dogs post-acute kidney injury.

## Key findings

- Persistent azotaemia is rare in dogs surviving beyond 3 months after acute kidney injury.
- Estimated glomerular filtration rate identifies kidney dysfunction in non-azotaemic dogs.
- Most dogs were classified as early-stage chronic kidney disease based on International Renal Interest Society guidelines.

## Abstract

To assess chronic kidney disease in dogs after azotaemic acute kidney injury utilising serum creatinine, symmetric dimethylarginine and estimated glomerular filtration rate.

Client‐owned dogs hospitalised for azotaemic acute kidney injury (T0) were evaluated at discharge (T1), 3 months (T2) and 12 (T3) months with serum creatinine and symmetric dimethylarginine measured. In non‐azotaemic dogs (serum creatinine <145 μmol/L) at T1 and T2, glomerular filtration rate was estimated by iohexol clearance. Acute kidney injury grade and chronic kidney disease stage were determined according to International Renal Interest Society guidelines. Non‐azotaemic dogs were considered to have kidney dysfunction if glomerular filtration rate was reduced ≥20% below the mean of the body weight category.

Fifteen dogs with azotaemic acute kidney injury were recruited. At T0 peak, acute kidney injury grade was III (n = 4), IV (n = 8) and V (n = 3). At T1, 10/15 dogs remained azotaemic. At T2, 3/15 dogs remained azotaemic; this persisted in 2/3 dogs at T3. One dog was euthanised prior to T3 due to progression of azotaemia (stage 4). Based on glomerular filtration rate assessment, 4/12 and 5/12 non‐azotaemic dogs had evidence of kidney dysfunction at T2 and T3, respectively. Ten out of 15 dogs were classified as International Renal Interest Society chronic kidney disease stage 1 and 4/15 dogs were stage 2 and 1/15 dog that did not survive to T3 was stage 4.

Persistent azotaemia occurs infrequently in dogs surviving beyond 3 months after acute kidney injury. Estimated glomerular filtration rate may identify continued kidney dysfunction in non‐azotaemic dogs.