Acute kidney injury in 18 cats after subcutaneous meloxicam and an update on non-steroidal anti-inflammatory drug usage in feline patients in Australia

Comparison of serum SDMA and creatinine as a biomarker for the detection of meloxicam-induced kidney injury in cats

Introduction

Serum symmetric dimethylarginine (SDMA) and creatinine are commonly used biomarkers of renal function in cats. We hypothesize that the serum analytes creatinine and SDMA are equally effective at detecting impaired renal function caused by meloxicam-induced renal injury in cats. Our primary objective was to compare serum concentrations of SDMA and creatinine in cats before, during, and after induction of renal injury from repeated dosages of meloxicam in the context of a small pilot study.

Methods

This follow-up study results from data collected in a well-controlled study that included 12 healthy female adult purpose-bred cats. Cats in the treatment group received meloxicam 0.3 mg/kg subcutaneously (SC) every 24 h for 31 days. Cats in the control group received saline (0.1 mL SC). Renal injury was defined as the presence of tubular damage, basement membrane damage, and/or interstitial inflammation in histological sections of kidney tissue. Serum creatinine and SDMA concentration were measured every 4 days.

Results

In the control group, no cats developed renal azotemia. In the treatment group, four out of six cats developed elevated serum creatinine and histopathological evidence of renal injury. Three of these cats developed an elevation in serum SDMA. The time to the development of renal azotemia using serum creatinine or SDMA was not significantly different (p > 0.05).

Discussion

In this pilot study, there was no evidence that serum SDMA was superior to serum creatinine at detecting impaired renal function caused by meloxicam-induced renal injury in cats.

Pharmacokinetics and effect on renal function and average daily gain in lambs after castration and tail docking, of firocoxib and meloxicam

AIMS

To evaluate and compare the pharmacokinetics of IM and oral firocoxib, and IM meloxicam, and detect their effect on renal function and average daily gain (ADG) in lambs undergoing tail docking and castration.

METHODS

Seventy-five male Romney lambs, aged 3-6 weeks, were randomised into five treatment groups (n = 15 per group): IM firocoxib (1 mg/kg); oral firocoxib (1 mg/kg); IM meloxicam (1 mg/kg); normal saline (approximately 2 mL, oral); or sham. Following the treatment administration, hot-iron tail docking and rubber ring castration were performed in all groups except the sham group, which did not undergo the procedures, but the animals were handled in the same manner as castrated and tail docked lambs. Blood samples were collected before and 1, 2, 4, 6, 8, 24, 48, 72, 96 and 120 hours after treatment administration, and drug concentrations in plasma were quantified by liquid chromatography and mass spectrometry. Plasma urea and creatinine concentrations were determined at a commercial laboratory. Lamb body weights were recorded before and 2, 4 and 8 weeks after tail docking and castration. The pharmacokinetic analysis was carried out using a non-compartmental approach. Between-group and between-time-point differences were compared using mixed model analyses.

RESULTS

There was no evidence for a difference in plasma elimination half-life between firocoxib given IM (LSM 18.6 (SE 1.4) hours), firocoxib given orally (LSM 18.2 (SE 1.4) hours), and meloxicam given IM (LSM 17. 0 (SE 1.4) hours). Firocoxib (IM) had a significantly greater volume of distribution (LSM 3.7 (SE 0.2) L/kg) than IM meloxicam (LSM 0.2 (SE 0.2) L/kg). Lambs in the meloxicam group had higher (p < 0.05) plasma urea and creatinine concentrations than those in the firocoxib, saline and sham groups. Lambs' ADG was decreased (p < 0.01) compared to the other treatment groups in the 0-2 week period following meloxicam administration.

CONCLUSIONS AND CLINICAL RELEVANCE

Both formulations of firocoxib had a long plasma elimination half-life and large volume of distribution. There was a transient reduction in ADG in the meloxicam group, possibly due to mild renal toxicity. Comparative studies on dose-response effects of firocoxib and meloxicam in lambs following the procedures are required.Abbreviations: ADG: Average daily gain; Cmax: Maximum concentration; COX: Cyclooxygenase; LOD: Limit of detection; NSAID: Non-steroidal anti-inflammatory drugs; CL: Plasma clearance; T1/2el: Plasma elimination half-life; Tmax: Time to achieve Cmax; Vd: Volume of distribution.

Serum amyloid A in cats with renal azotemia

Background and Aim

The concentration of the feline acute-phase protein serum amyloid A (SAA) increases in cats with acute inflammatory diseases. However, it is unclear whether SAA concentration increases in cats with azotemic kidney disease or whether it can aid in differentiating acute kidney injury (AKI) from chronic kidney disease (CKD). Similarly, whether SAA concentration can be used as a prognostic marker is also unclear. Therefore, this study aimed to evaluate the SAA concentrations in cats with azotemic kidney disease and determine whether SAA concentrations can be used to differentiate between AKI, CKD, and "acute on CKD" (AoC). In addition, we evaluated whether SAA concentration could serve as a prognostic parameter. Moreover, we determined the correlations between SAA concentration and temperature; creatinine, urea, and albumin concentrations; leukocyte count; and urine protein/creatinine (UP/C).

Materials and Methods

Forty-eight client-owned azotemic cats (creatinine >250 μmol/L) were included in this prospective study. Cats with pre- and post-renal azotemia were excluded from the study. The causes of azotemia were differentiated into AKI, CKD, and AoC. The SAA concentrations were analyzed through turbidimetric immunoassay at the time of admission. Data were analyzed using the Mann-Whitney U, Kruskal-Wallis, Chi-Square, Fisher's exact, and Spearman correlation tests. p ≤ 0.05 was considered statistically significant.

Results

Serum amyloid A concentration increased in 5/12 cats with AKI, 7/22 cats with CKD, and 9/14 cats with AoC (p = 0.234). The median SAA concentration in cats with AKI, CKD, and AoC whose SAA concentration was ≥5 mg/L was 174 mg/L (10-281 mg/L), 125 mg/L (6-269 mg/L), and 143 mg/L (7-316 mg/L), respectively (p = 0.697), with no significant differences observed between the groups. The median SAA concentration did not differ significantly between survivors (125 mg/L, 10-316 mg/L) and non-survivors (149 mg/L, 6-281 mg/L; p = 0.915) with SAA concentration ≥5 mg/L.

Conclusion

Serum amyloid A concentration increased in 44% of the cats with azotemia. However, it cannot be used to differentiate AKI from CKD or as a prognostic marker. Serum amyloid A concentration was correlated with neutrophil count, albumin concentration, and UP/C, and the presence of comorbidities may influence SAA concentration.