Acute kidney injury in cats and dogs: A proportional meta-analysis of case series studies

Incidence of postoperative acute kidney injury in dogs without pre-existing renal disease

Acute kidney injury (AKI) is defined as a sudden reduction in renal function, characterized by a rapid increase in serum creatinine (sCr) ≥ 0.3 mg/dL within 48 h with or without azotemia (sCr ≥ 1.7 mg/dL) and/or oliguria (urinary output <1 mL/kg/h for more than 6 h). Acute kidney injury is associated with increased mortality, prolonged hospitalization, and higher costs in both human and veterinary medicine. This study aimed to determine the incidence of postoperative AKI in dogs without pre-existing renal disease. A total of 170 dogs, admitted for elective surgery (ASA I-II) at a single university center, were included. The sCr levels were measured at the following times: procedure day (before anesthesia), 24 h, 48 h, and 7 days post-surgery (0 h, 24 h, 48 h, and 7d). Potential risk factors for AKI including patient characteristics (age, sex, pathologies, treatments), anesthetic protocol (drugs, type and rate of fluid therapy, procedure duration) and intraoperative complications were analyzed. Postoperative AKI was identified in 5 dogs (2.9, 95% CI: 1.3-6.7%) based on a sCr increase ≥0.3 mg/dL within 48 h post-surgery. A decrease in sCr (Mean: 0.87 SD = 0.2) was observed at 48 h (Mean: 0.84 SD = 0.24) (p < 0.001), returning to baseline by day 7 (Mean:0.89 SD = 0.22) (p = 0.127). Only a relationship between surgery duration and the probability of developing postoperative AKI was found (p = 0.037). Further studies are warranted to identify risk factors for AKI in dogs undergoing GA and improve its prevention optimizing postoperative management and prognosis.

Outcome in Critically Ill Dogs and Dogs With Acute Kidney Injury Based on Neutrophil Gelatinase-Associated Lipocalin and Tissue Inhibitor of Metalloproteinase-2

BACKGROUND

Neutrophil gelatinase-associated lipocalin (NGAL) and tissue inhibitor of metalloproteinase-2 (TIMP-2) have potential as early biomarkers for acute kidney injury (AKI) in dogs.

OBJECTIVES

Assess whether NGAL and TIMP-2 at admission (T0) and 24 h later (T1) identify survival in critically ill (CI) and AKI dogs, development of hospital-acquired AKI in CI dogs, and development of chronic kidney disease (CKD) in AKI dogs after 3 months.

ANIMALS

Sixty-two client-owned dogs: 10 healthy, 24 with AKI, and 28 CI.

METHODS

Prospective study with blood and urine samples collected at T0, T1, and up to 1 week in CI dogs, 1 month in healthy dogs, and 3 months in AKI dogs. Serum and urinary NGAL (sNGAL; uNGAL) and urinary TIMP-2 (uTIMP-2) were measured using validated ELISA kits.

RESULTS

Dogs with AKI that did not survive had significantly higher uNGAL concentrations and u/sNGAL ratios at T0 compared with survivors (p = 0.05, n = 23; and p = 0.03, n = 21, respectively). In CI dogs, sNGAL was significantly higher in non-survivors at T0 and T1 compared with survivors (p = 0.02, n = 26; and p = 0.003, n = 26, respectively). At T0, normalized urinary tissue inhibitor of metalloproteinase-2 (unormTIMP-2) was significantly higher in non-survivor CI dogs compared with survivors (p = 0.04, n = 25). No significant differences were found for the other variables.

CONCLUSIONS AND CLINICAL RELEVANCE

In AKI dogs, uNGAL and u/sNGAL at T0, and in CI dogs, sNGAL at T0 and T1 and unormTIMP-2 at T0, were potential predictors of survival.

Apoptosis Inhibitor of Macrophage (CD5-Like Antigen) in Healthy Dogs and Dogs With Acute Kidney Injury

BACKGROUND

Apoptosis inhibitor of macrophage (AIM) is a fundamental mediator of recovery from acute kidney injury (AKI) in mice, but its role in AKI in dogs is unknown.

HYPOTHESIS/OBJECTIVES

To detect and quantify AIM in serum and urine from both healthy dogs and dogs with AKI, and to determine if AIM is higher in dogs with AKI compared to healthy controls.

ANIMALS

Eight dogs with International Renal Interest Society (IRIS) Grade II-V AKI and 10 healthy adult dogs.

METHODS

Retrospective case-control study. Liquid chromatography-mass spectrometry (LC-MS) based targeted proteomics was used to quantify AIM. AIM peak areas were compared between the AKI and healthy cohorts and correlated with selected markers of renal function.

RESULTS

AIM was able to be quantified in the urine of 5/8 dogs with AKI and 1/10 healthy dogs. AIM was quantified in the serum of all dogs, and there was no difference in peak area between the two groups (AKI: median, 67 840 (range, 9797-98 725); control: median, 79 072 (range, 46 400-160 330); p = 0.274). In dogs with AKI, AIM was not correlated with serum creatinine, blood urea nitrogen, phosphorus, or potassium concentrations, urine specific gravity, or IRIS AKI grade.

CONCLUSIONS AND CLINICAL IMPORTANCE

AIM was predominantly detected in the urine of dogs with AKI and not in the urine of healthy dogs.

Parathyroid Hormone Concentration in Dogs Affected by Acute Kidney Injury Compared with Healthy and Chronic Kidney Disease

Information about parathyroid hormone (PTH) status in the course of AKI is lacking. In contrast, renal secondary hyperparathyroidism (RSHPT) is a well-known consequence of canine chronic kidney disease (CKD). This study aimed to investigate PTH status in dogs affected by AKI, comparing PTH concentrations between healthy dogs, dogs affected by AKI and dogs affected by CKD. Three groups of dogs (35 affected by AKI, 35 affected by CKD and 41 healthy) were retrospectively included. PTH concentrations were significantly higher in both the AKI and CKD groups (p < 0.0001) compared to healthy ones but without significant differences between the AKI and CKD groups. In the AKI group, increased PTH was detected in 88.6% of dogs. Moreover, in AKI dogs, PTH increases with AKI grading and is correlated with serum creatinine (p < 0.0001; r = 0.67) and phosphate concentrations (p < 0.0001; r = 0.74). PTH in AKI dogs was not correlated with total calcium (tCa), while it was negatively correlated with ionized calcium (iCa) (p < 0.0037; r = -0.53). Higher PTH concentrations also occurred in canine AKI, as reported in canine CKD and human AKI, presumably as a rapid response to ionized hypocalcemia and hyperphosphatemia, frequently reported in our patients. PTH seems not to be a useful tool in distinguishing AKI and CKD.

Diagnostic efficacy of urinary neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 for early detection of acute kidney injury in dogs with leptospirosis or babesiosis

This study evaluates the diagnostic efficacy of urinary biomarkers, Neutrophil Gelatinase-Associated Lipocalin (uNGAL), and Kidney Injury Molecule-1 (uKIM-1), in identifying Acute Kidney Injury (AKI) in dogs affected with leptospirosis or babesiosis. Acute kidney injury was diagnosed based on the increase in serum creatinine levels above 0.3 mg/dL within 48 h and dogs were categorized according to AKI grades based on International Renal Interest Society guidelines. Traditional biomarkers (serum creatinine and blood urea nitrogen) and novel biomarkers like urinary NGAL and urinary KIM-1 levels were measured and compared to concentrations obtained in control dogs. Statistical analysis assessed significant differences (P < 0.01) across AKI grades, specifically noting elevated urinary NGAL and KIM-1 in IRIS grade I AKI (P < 0.001). The study highlights the diagnostic significance of urinary NGAL and KIM-1 as early indicators of renal damage, particularly valuable in non-azotemic AKI cases, offering promising markers for early AKI diagnosis in veterinary clinical settings. These biomarkers demonstrate clinical utility and underscore their potential for improving AKI management in veterinary medicine. Further validation studies involving larger cohorts and diverse etiologies of AKI are needed to confirm the diagnostic accuracy and clinical utility of urinary NGAL and KIM-1 in veterinary practice.

Successful hemodialysis treatment of a Quarter Horse mare with silver maple leaf toxicity and acute kidney injury

An adult American Quarter Horse mare presented for pigmenturia and lethargy of 12 hours' duration and was diagnosed with silver maple leaf toxicity. The mare had intravascular hemolysis and azotemia. The mare was treated with a transfusion of whole blood, fluids administered IV, antibiotics, oxygen insufflation, and supportive care. The azotemia persisted despite conventional medical management and hemodialysis was elected. After 2 intermittent hemodialysis treatments over 3 days, the azotemia almost resolved, clinical signs improved, and the mare was discharged. The blood urea nitrogen, creatinine, and electrolyte concentrations remained normal 6 months later after examination by the referring veterinarian. Hemodialysis treatment can be feasible in horses if equipment and expertise are available and should be considered as a treatment option if indicated.

International Renal Interest Society best practice consensus guidelines for the diagnosis and management of acute kidney injury in cats and dogs

Acute kidney injury (AKI) is defined as an injury to the renal parenchyma, with or without a decrease in kidney function, as reflected by accumulation of uremic toxins or altered urine production (i.e., increased or decreased). AKI might result from any of several factors, including ischemia, inflammation, nephrotoxins, and infectious diseases. AKI can be community- or hospital-acquired. The latter was not previously considered a common cause for AKI in animals; however, recent evidence suggests that the prevalence of hospital-acquired AKI is increasing in veterinary medicine. This is likely due to a combination of increased recognition and awareness of AKI, as well as increased treatment intensity (e.g., ventilation and prolonged hospitalization) in some veterinary patients and increased management of geriatric veterinary patients with multiple comorbidities. Advancements in the management of AKI, including the increased availability of renal replacement therapies, have been made; however, the overall mortality of animals with AKI remains high. Despite the high prevalence of AKI and the high mortality rate, the body of evidence regarding the diagnosis and the management of AKI in veterinary medicine is very limited. Consequently, the International Renal Interest Society (IRIS) constructed a working group to provide guidelines for animals with AKI. Recommendations are based on the available literature and the clinical experience of the members of the working group and reflect consensus of opinion. Fifty statements were generated and were voted on in all aspects of AKI and explanatory text can be found either before or after each statement.

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.

Anemia in Dogs with Acute Kidney Injury

Anemia is a well-known complication in CKD dogs, but its frequency in AKI dogs has been poorly investigated. The aim of the present study was to retrospectively evaluate frequency, degree of severity, and regeneration rate of anemia in relation to IRIS grade, etiology, therapy, and outcome. Medical records of dogs (2017-2023) with historical, laboratory, and ultrasound findings consistent with AKI were retrospectively reviewed. According to etiology, AKI was classified as ischemic/inflammatory (IS), infectious (INF), nephrotoxic (NEP), obstructive (OBS), and unknown (UK). AKI dogs were also classified according to therapeutical management (medical vs. hemodialysis), survival to discharge (survivors vs. non-survivors). Anemia was defined as HCT < 37% and classified as mild (HCT 30-37%), moderate (HCT 20-29%), severe (13-19%), or very severe (<13%). Anemia was classified as microcytic (MCV < 61 fL), normocytic (61 and 73 fL), and macrocytic (>73 fL). Anemia was considered hypochromic (MCHC< 32 g/dL), normochromic (32 and 38 g/dL), and hyperchromic (>38 g/dL). Regeneration rate was considered absent (RET ≤ 60,000/μL), mild 61,000-150,000/μL), and moderate (>150,000/μL). A total of 120 AKI dogs were included in the study, and anemia was found in 86/120 dogs (72%). The severity of anemia was mild in 32/86 dogs (37%), moderate in 40/86 dogs (47%), severe in 11/86 dogs (13%), and very severe in 3/86 (3%). Anemia was normochromic in 71/86 dogs (83%), hyperchromic in 12/86 dogs (14%), and hypochromic in 3/86 dogs (3%). Normocytic anemia was present in 56/86 dogs (65%), microcytic anemia in 27/86 dogs (31%), and macrocytic anemia in 3/86 dogs (4%). Non-regenerative anemia was found in 76/86 dogs (88%). The frequency of anemia increased significantly (p < 0.0001) with the progression of IRIS grade, although no significant difference in the severity of anemia was found among the IRIS grades. The frequency of non-regenerative forms of anemia was significantly higher than regenerative forms (p < 0.0001) in all IRIS grades. In our population of AKI dogs, anemia was a very frequent finding, in agreement with current findings in human nephrology.

A Clinical Study on Urinary Clusterin and Cystatin B in Dogs with Spontaneous Acute Kidney Injury

Novel biomarkers are needed in diagnosing reliably acute kidney injury (AKI) in dogs and in predicting morbidity and mortality after AKI. Our hypothesis was that two novel tubular biomarkers, urinary clusterin (uClust) and cystatin B (uCysB), are elevated in dogs with AKI of different etiologies. In a prospective, longitudinal observational study, we collected serum and urine samples from 18 dogs with AKI of different severity and of various etiology and from 10 healthy control dogs. Urinary clusterin and uCysB were compared at inclusion between dogs with AKI and healthy controls and remeasured one and three months later. Dogs with AKI had higher initial levels of uClust (median 3593 ng/mL; interquartile range [IQR]; 1489-10,483) and uCysB (554 ng/mL; 29-821) compared to healthy dogs (70 ng/mL; 70-70 and 15 ng/mL; 15-15; p < 0.001, respectively). Initial uCysB were higher in dogs that died during the one-month follow-up period (n = 10) (731 ng/mL; 517-940), compared to survivors (n = 8) (25 ng/mL; 15-417 (p = 0.009). Based on these results, uClust and especially uCysB are promising biomarkers of AKI. Further, they might reflect the severity of tubular injury, which is known to be central to the pathology of AKI.

Retrospective evaluation of 22 dogs with leptospirosis treated with extracorporeal renal replacement therapies (2018-2021)

BACKGROUND

Outcomes of dogs with acute kidney injury secondary to leptospirosis (AKI-L) treated using renal replacement therapies (RRT) are poorly characterized.

HYPOTHESIS/OBJECTIVES

Describe survival to discharge, short (≤30 days) and long-term (≥6 months) outcomes of AKI-L dogs receiving RRT and determine if there is a significant difference in maximum blood urea nitrogen (maxBUN), maximum creatinine (maxCr), maximum bilirubin (maxBili) and the number of body systems affected between survivors and non-survivors.

ANIMALS

Twenty-two client-owned dogs with AKI-L receiving RRT.

METHODS

Retrospective medical record review of dogs with AKI-L that received RRT between 2018 and 2021.

RESULTS

Sixteen of 22 (73%) dogs survived to discharge. Of the survivors, 13 (81%) were alive >30 days from discharge and 12 (75%) were alive at 6 months from discharge. Factors significantly higher in non-survivors included number of body systems affected (survivors: 1 (19%), 2 (50%), 3 (25%) and 4 (6%) vs non-survivors: 3 (33.3%), and 4 (66.7%); P = .01) and median maxBili (survivors: 1.9 mg/dL; range, 0.1-41.6 vs non-survivors: 21.0 mg/dL; range, 12.3-38.9; P = .02). There was no significant difference in median maxBUN (survivors: 153.0 mg/dL; range, 67-257 vs non-survivors: 185.5 mg/dL; range, 102-218; P = .44) and median maxCr (survivors: 9.8 mg/dL; range, 6.2-15.9 vs non-survivors: 9.8 mg/dL; range, 8.4-13.5; P = .69) between survivors and non-survivors.

CONCLUSIONS AND CLINICAL IMPORTANCE

Regardless of azotemia severity, dogs with AKI-L receiving RRT have a good survival rate to discharge. The number of body systems affected and hyperbilirubinemia might be associated with worse outcomes.

Nephrology in Veterinary Medicine

Veterinary nephrology is a specialized field of veterinary medicine providing a high level of care for animals with all types of kidney disease. Veterinarians complete extensive training to become board-certified in veterinary nephrology-urology. Companion animal nephrology is the most advanced field; however, all species are afflicted by a variety of renal disorders. Most naturally occurring animal kidney diseases have similar disorders found in people; where veterinary research is lacking, clinical management is often modified from standard of care in people. Veterinarians have become adept at scaling down procedures to safely perform them on dogs and cats weighing only a few kilograms. Advanced diagnostics (renal biopsy, cystoscopy, fluoroscopic studies, etc. ) and therapeutics (renal replacement therapy, interventional endourology, etc. ) are commonly performed within the practice of veterinary nephrology-urology. Collaboration between veterinary and human nephrologists may advance both disciplines and improve care for people and animals alike.

Accuracy of Crit-Line® monitors in predicting hematocrit and change in blood volume of dogs during hemodialysis

BACKGROUND

Ultrafiltration (UF) is an extracorporeal technique for treating fluid overload and is monitored with noninvasive blood volume monitors.

HYPOTHESIS/OBJECTIVES

The primary objective was to determine the accuracy of Crit-Line® III and IV noninvasive blood volume monitors to estimate canine packed cell volume (PCV) and changes in blood volume during UF. A secondary aim was to determine accuracy of targeted ultrafiltration rates (UFR) compared to calculated delivered UFR.

METHODS

An ex vivo study with a single Phoenix® X36 platform and canine packed red blood cells (pRBC) was performed. Through dilution and UF, clinically applicable PCV values were obtained and compared to Crit-Line® hematocrit (Hct). Blood volume was constantly measured and compared to targeted UFR. Systematic and proportional bias were calculated using a Bayes method.

RESULTS

Crit-Line® III and IV reported Hct was significantly lower than PCV (n = 140, median 26%, range, 8%-50%) when PCV was >25% and >30%, respectively. Crit-Line® III and IV calculated change in blood volume (ΔBV%) was significantly different from measured blood volume changes at ΔBV% ±20% and >-20%, respectively. Comparing targeted and delivered UFR (mL/h), less than targeted UFR was removed at UFR100 through UFR400 and UFR0 adding volume.

CONCLUSIONS AND CLINICAL IMPORTANCE

Crit-Line® III and IV monitors provide accurate estimates of canine PCV and UF volume change within specific ranges and are useful in monitoring canine UF and hemodialysis. Veterinary hemodialysis services should evaluate individual machines for UFR inaccuracies, which can meaningfully affect small animals.

The Nephroprotective Effect of Cornelian Cherry (Cornus mas L.) and Rowanberry (Sorbus aucuparia L.) in Gentamicin-Induced Nephrotoxicity on Wistar Rats with Emphasis on the Evaluation of Novel Renal Biomarkers and the Antioxidant Capacity in Correlation with Nitro-Oxidative Stress

In spite of its well-known nephrotoxicity, gentamicin is nonetheless routinely used in humans and animals. However, no adjuvant treatments have been implemented to mitigate this harmful effect. Given this concern, medicinal plants represent a significant reservoir of natural antioxidants that could potentially reduce the renal oxidative stress induced by gentamicin. Therefore, the main objective of this research was to investigate the nephroprotective properties of Cornus mas and Sorbus aucuparia fruits in an experimental model of nephrotoxicity. The 3-week study was performed on male Wistar rats, which were randomly divided into six experimental groups, being subcutaneously treated with 50 mg/kg gentamicin and orally given Cornus mas and Sorbus aucuparia extracts, in doses of 40 mg/kg and 10 mg/kg, respectively. Antioxidant therapy significantly improved the nitro-oxidative stress parameters as well as the specific renal biomarkers KIM-1 and iNAG, demonstrating a considerable renal tubular protective impact. These outcomes were reinforced by biochemical and histopathological enhancements. Nevertheless, neither of the tested extracts succeeded in substantially diminishing BUN levels. Additionally, CysC did not significantly decline following extracts treatment, suggesting that the remedies did not effectively protect renal glomeruli against gentamicin stress. Future studies are required in order to determine the underlying mechanisms of these berries.

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.

Hemostatic and thromboelastographic parameters in dogs with renal azotemia

Background and Aim

Humans and dogs with azotemia can develop coagulation disorders. Therefore, this study aimed to evaluate the coagulation profiles and thromboelastographic parameters in dogs with acute kidney injury (AKI) and chronic kidney disease (CKD).

Materials and Methods

In this prospective study, 31 client-owned dogs with renal azotemia (creatinine >220 μmol/L) were enrolled. Clinical signs of hemostatic disorders, complete blood count, coagulation profile, D-dimers, thromboelastography, and 28-day survival data were obtained and analyzed using the t-test, Mann-Whitney U test, and Chi-square test. Statistical significance was set at p < 0.05.

Results

Seventeen dogs with AKI, 10 with CKD, and four with acute-on-chronic kidney injury (AoC) were enrolled. Ten dogs (AKI, 8/17; CKD, 2/10) had thrombocytopenia. Prothrombin time was prolonged in four dogs with AKI and longer in dogs with AKI than in dogs with CKD (p = 0.004). The activated partial thromboplastin time was prolonged in 23 dogs (AKI, 14/17; CKD, 7/10; AoC, 3/4) and was longer in azotemic dogs than in healthy control dogs (p = 0.003). Thromboelastographic tracings were hypocoagulable in three dogs with AKI and hypercoagulable in 16 dogs (AKI 4/17, CKD 9/10, AoC 3/4). The thromboelastographic values for maximum amplitude (p < 0.001) and global clot strength (p < 0.001) were lower in dogs with AKI than in those with CKD.

Conclusion

Hypercoagulable thromboelastographic tracings were observed in dogs with CKD, whereas coagulation times were prolonged in dogs with AKI. However these findings should be validated by further studies.

Continuous renal replacement therapy is a safe and effective modality for the initial management of dogs with acute kidney injury

OBJECTIVE

To describe the management of dogs with acute kidney injury (AKI) by continuous renal replacement therapy (CRRT), and to investigate the relationship between a prescribed CRRT dose, the hourly urea reduction ratio (URR), and the overall efficacy.

ANIMALS

45 client-owned dogs diagnosed with severe AKI, receiving 48 CRRT treatments at a veterinary teaching hospital.

PROCEDURES

Retrospective study. Search of medical records of dogs with AKI managed by CRRT.

RESULTS

Median serum urea and creatinine at CRRT initiation were 252 mg/dL [Inter quartile range (IQR), 148 mg/dL; range, 64 to 603 mg/dL] and 9.0 mg/dL (IQR, 7 mg/dL; range, 4.3 to 42.2 mg/dL), respectively. Median treatment duration was 21 hours (IQR, 8.8 hours; range, 3 to 32 hours). Systemic heparinization and regional citrate anticoagulation were used in 24 treatments each (50%). The prescribed median CRRT dose for the entire treatment was 1 mL/kg/min (IQR, 0.4 mL/kg/min; range, 0.3 to 2.5 mL/kg/min). The median hourly URR was 4% (IQR, 1%; range, 2% to 12%), overall URR was 76% (IQR, 30%; range, 11% to 92%) and median Kt/V was 2.34 (IQR, 1.9; range, 0.24 to 7.02). The CRRT dose was increased gradually from 0.9 mL/kg/min to 1.4 mL/kg/min (P < .001) and the hourly URR decreased from 6.5% to 5.5% (P = .05). The main complication was clotting of the extra-corporeal circuit, occurring in 6/48 treatments (13%). Twenty-four dogs (53%) survived to discharge.

CLINICAL RELEVANCE

CRRT is safe when the prescription is based on the current veterinary guidelines for gradual urea reduction. Treatment efficacy can be maximized by gradually increasing the dose according to the actual URR.

Urine bacterial culture growth and association with urine sedimentation and clinical findings in cats with acute kidney injury

OBJECTIVES

A urine culture is often pursued in cats with acute kidney injury (AKI) to screen for bacterial growth in the urine, but it can be cost prohibitive. The aim of the study was to determine the ability of a urinalysis and lower urinary tract signs (LUTS) to predict urine culture results in cats with AKI.

METHODS

Ninety-seven cats with AKI were included in this study. This was a retrospective, observational study. Medical records from 2008 to 2018 were reviewed to identify cats with AKI that had a paired urinalysis and urine bacterial culture. The sensitivity, specificity, positive predictive value and negative predictive values of microscopic bacteriuria, pyuria, hematuria and the presence of LUTS for predicting urine culture results was calculated.

RESULTS

Thirty-two percent of cats (n = 31) had a positive urine culture. Of these, 28 (90%) had bacteriuria, 21 (68%) had pyuria, 13 (42%) had hematuria and 10 (32%) had LUTS. Of the 42 cats without hematuria or pyuria, seven had a positive urine culture (17%). Bacteriuria had a high sensitivity (90%) and specificity (92%) for predicting urine culture bacterial growth. The absence of bacteriuria had a high negative predictive value for no bacterial growth (95%). The odds of a positive urine culture were increased with bacteriuria (odds ratio [OR] 114, 95% confidence interval [CI] 29-621; P <0.001), pyuria (OR 21, 95% CI 7-70; P <0.001) and LUTS (OR 5, 95% CI 1.7-16; P = 0.004). Hematuria was not associated with a positive culture (sensitivity 42%, specificity 52%).

CONCLUSIONS AND RELEVANCE

Microscopic bacteriuria and pyuria on urine sediment evaluation and LUTS can be helpful for predicting bacterial culture results in cats with AKI and in settings where submitting a urine culture may not be financially feasible.

Evaluation of presentation, treatment and outcome in hypertensive emergency in dogs and cats: 15 cases (2003-2019)

OBJECTIVES

Hypertensive emergency is well recognised in human medicine, yet there is limited veterinary evidence. This study aimed to determine the presentation, treatment and outcome in dogs and cats with hypertensive emergency.

MATERIALS AND METHODS

A retrospective case series of dogs and cats with hypertensive emergency identified as follows: acute history with non-invasive Doppler systolic blood pressure greater than 180 mmHg and target organ damage including acute onset seizures, altered mentation with or without lateral recumbency or blindness. Data collected included signalment, history, physical examination and clinicopathological findings, systolic blood pressure, antihypertensive treatment and outcome.

RESULTS

Seven dogs and eight cats were included presenting with seizures (n=9), blindness (n=4), altered mentation with (n=2) or without (n=2) lateral recumbency. Median age was 9 years (range 1 to 15) and duration of clinical signs before presentation was 1.5 days (range 1 to 15). Median systolic blood pressure on presentation was 230 mmHg (range 190 to 300). Amlodipine was the most common first-line agent (n=10), followed by hydralazine (n=4) and hypertonic saline (n=1). Aetiology of hypertensive emergency was acute kidney injury (n=9), idiopathic hypertension (n=3), hyperthyroidism (n=1), lymphoma (n=1) and suspected cutaneous and renal glomerular vasculopathy (n=1). Five cats and three dogs survived to discharge with an overall survival of 53.3%.

CLINICAL SIGNIFICANCE

Hypertensive emergencies had various presenting signs in this series. AKI was considered to be the cause of hypertension in the majority of patients. Further evaluation of treatment for hypertensive emergencies is warranted, considering almost half of the cases did not survive to discharge.

Evaluation of symmetric dimethylarginine in cats with acute kidney injury and chronic kidney disease

Background

Serum symmetric dimethylarginine (SDMA) concentrations are considered a biomarker for renal dysfunction in dogs and humans with acute kidney injury (AKI). No studies have assessed SDMA in cats with AKI.

Hypothesis/Objectives

SDMA correctly identifies cats with azotemic AKI.

Animals

Fifteen control cats, 22 with novel AKI, 13 with acute on chronic‐AKI (AoC) and 19 with chronic kidney disease (CKD).

Methods

Retrospective study. Cats with azotemia (serum creatinine concentrations >1.7 mg/dL) were defined as having AKI or CKD based on history, clinical signs, clinicopathological findings and diagnostic imaging, and classified using the International Renal Interest Society (IRIS) grading/staging systems. Serum SDMA concentrations were compared between groups with nonparametric methods, and correlations assessed using Spearman's correlation coefficient. Data are presented as median [range].

Results

SDMA concentrations were 11 (8‐21) μg/dL, 36 (9‐170)μg/dL, 33 (22‐75) μg/dL and 25 (12‐69) μg/dL in control, novel AKI, AoC and CKD cats. SDMA concentrations were significantly higher in cats with novel AKI (P < .001), AoC (P < .001) and CKD (P < .01) compared to controls. SDMA concentrations were significantly higher in cats with more advanced AKI (IRIS grade IV‐V) compared to less severe AKI (IRIS grade II). Serum creatinine and SDMA concentrations had a significant correlation in cats with novel AKI (r_s = 0.826, n = 22; P < .001) and a significant correlation when all cats across all 4 groups were considered together (r_s = 0.837, n = 69; P < .001).

Conclusions and Clinical Importance

Serum SDMA concentrations are elevated in cats with established AKI (novel and AoC) and CKD, providing evidence for use of SDMA as a biomarker for AKI in cats.

Cystatin C assay validation using the immunoturbidimetric method to evaluate the renal function of healthy dogs and dogs with acute renal injury

Background and Aim: Acute kidney injury (AKI) is associated with a grave prognosis. A clinical assessment of kidney function can be performed based on the glomerular filtration rate (GFR). Cystatin C (CysC) can indicate the GFR or kidney function and its measurement is currently performed using immunological methods such as nephelometry, immunoturbidimetry, and enzyme-linked immunosorbent assays in human medicine. However, these techniques are not specific for use in veterinary medicine. This study aimed to validate an immunoturbidimetric assay for serum CysC (sCy) in dogs, determine the sCy reference intervals for healthy dogs, evaluate sCy stability in serum samples, and compare sCy with serum creatinine (sCr) in healthy dogs and dogs with AKI. Materials and Methods: Forty-three dogs were divided into a control group (n = 19) and an AKI group (n = 24). An immunoturbidimetric method including commercially available human CysC calibrated with canine CysC was used to evaluate canine serum samples. Results: An average recovery of 97% was observed for canine serum samples. The reference interval for CysC in healthy dogs was 0.57–1.29 mg/L. The sCy concentration in dogs with AKI was significantly higher (2.82 ± 1.46 mg/L) than in healthy dogs (0.93 ± 0.18 mg/L). Statistical analysis confirmed a strong correlation between sCy and sCr (r = 0.94; p < 0.05) in dogs with AKI. Conclusion: The immunoturbidimetric method of evaluating sCy yielded satisfactory results and can be used for canine samples when a species-specific calibrator is used. Furthermore, sCy is a reliable marker of renal dysfunction in dogs. It is best to store samples for sCy evaluation at temperatures between 4°C and 8°C.

Long-term outcome of dogs recovering from acute kidney injury: 132 cases

Background

Information regarding long‐term outcome of dogs recovering from acute kidney injury (AKI) is limited.

Objectives

Determine the long‐term outcome of dogs recovering from AKI and identify predictors for serum creatinine concentration (sCr) normalization and long‐term outcome.

Animals

One hundred thirty‐two dogs with AKI that survived ≥30 days postdischarge.

Methods

Retrospective study. Search of medical records of dogs diagnosed with AKI that survived to discharge. Follow‐up data were retrieved from medical records and by telephone interviews with the owners or primary care veterinarians or both.

Results

Estimated median survival time (MST) was 1322 days (95% confidence interval [CI], 1147‐1626), and 76% of the dogs were alive at last contact. Normalization of sCr was documented in 55% of the dogs at discharge and in additional 20% during the follow‐up period. The proportion of dogs with sCr normalization decreased with increase in AKI grade (P = .02). Long‐term survival was not associated with sCr normalization (P = .63). Etiology was associated with the long‐term outcome (P = .004).

Conclusion and Clinical Importance

Long‐term survival of dogs with AKI is longer than previously described. Normalization of sCr in 99 dogs (75%) occurred, either at discharge or within the follow‐up period. Normalization of sCr was not associated with long‐term survival. Estimated MST of dogs with sCr normalization was not different compared with dogs that developed azotemic chronic kidney disease (CKD), presumably because of slow CKD progression rate. Etiology is an important factor determining sCr normalization and long‐term survival, emphasizing the importance of the reversibility of renal injury rather than its severity.

Acute kidney injury in dogs: Etiology, clinical and clinicopathologic findings, prognostic markers, and outcome

BACKGROUND

Acute kidney injury (AKI) is a common, potentially fatal condition.

OBJECTIVES

To characterize the etiologies, clinical and clinicopathologic findings, hospitalization period, and outcome of dogs with AKI and to identify markers of negative prognosis.

ANIMALS

Two hundred forty-nine client-own dogs diagnosed with AKI and hospitalized at a veterinary teaching hospital.

METHODS

Retrospective study. Search of medical records for dogs with AKI.

RESULTS

Common clinical signs included lethargy (225/249, 90%), anorexia (206/249, 83%), and vomiting (168/249, 68%). Etiologies included ischemic/inflammatory (144/249, 58%), infectious (19/249, 8%), nephrotoxicosis (14/249, 6%), or other (13/249, 5%). Hospital-acquired AKI was diagnosed in 9% (23/249) of the dogs. Median presentation and peak serum creatinine (sCr) concentrations were 4 mg/dL (range, 1.1-37.9) and 4.6 mg/dL (range, 1.1-43.1), respectively. Dogs were classified to AKI grades as follows: Grade I, 6 (2%), Grade II, 38 (15%), Grade III, 89 (36%), Grade IV, 77 (31%), and Grade V, 39 (16%). One hundred and sixty-four (66%) dogs survived. There was a positive association between death and AKI grade (P = .009). The case fatality rate was higher among dogs with anuria compared with dogs without anuria (50% vs 28%, respectively; odds ratio [95% confidence interval]: 2.5 [1.39-4.6]; P = .002). Forty-seven (18.8%) dogs underwent hemodialysis, of which 60% survived.

CONCLUSION AND CLINICAL IMPORTANCE

Two-thirds of dogs with AKI survived. Hospital-acquired AKI was common. The severity of AKI, as reflected by presence of anuria, AKI grade, and other body organs involvement, was associated with the outcome.

Prospective evaluation of novel biomarkers of acute kidney injury in dogs following cardiac surgery under cardiopulmonary bypass

OBJECTIVE

To assess the occurrence of acute kidney injury (AKI) in dogs undergoing cardiac surgery under cardiopulmonary bypass (CPB) and explore associations between traditional and novel serum and urinary biomarkers.

DESIGN

Prospective cohort study conducted between July 2018 and April 2019.

SETTING

University teaching hospital.

ANIMALS

Nineteen dogs undergoing cardiac surgery under CPB with preoperative serum creatinine <140 μmol/L (<1.6 mg/dl).

INTERVENTIONS

Blood and urine samples were obtained at 4 time points: preoperatively following general anesthesia induction, immediately postoperatively, and 2 and 4 days postoperatively (T₁ , T₂ , T₃ , and T₄ ). AKI was defined as an increase in serum creatinine ≥26.4 μmol/L (≥0.3 mg/dl) above baseline within 48 hours. Serum creatinine, C-reactive protein (CRP), symmetric dimethylarginine (SDMA), inosine, beta-aminoisobutyric acid (BAIB), urinary clusterin (uClus), and urinary cystatin B (uCysB) were measured. Data were log-transformed (log₁₀ ) when appropriate and assessed using linear mixed-effects models.

MEASUREMENTS AND MAIN RESULTS

AKI occurred in 3 of 19 dogs (15.8%, 95% confidence interval: 0.047-0.384). Inosine increased at T₂ (adjusted mean ± standard error: 53 ± 5.6) in all dogs, and then gradually decreased. Log₁₀ uCysB increased at T₂ (2.3 ± 0.1) in all dogs and remained high. Log₁₀ CRP and log₁₀ uClus increased significantly at T₃ (1.9 ± 0.1 and 3.6 ± 0.1, respectively) in all dogs and remained increased. There was a significant positive association between serum creatinine and SDMA (P < 0.001, estimate ± standard error: 0.06 ± 0.00), between log₁₀ CRP and log₁₀ uClus (P < 0.001, 0.35 ± 0.08), between SDMA and creatinine as well as between SDMA and BAIB (P < 0.001, 11.1 ± 0.83 and P < 0.001, 1.06 ± 0.22, respectively) for all dogs at all time points.

CONCLUSIONS

Inosine and uCysB concentrations changed in all dogs immediately following a surgery under CPB and may indicate tubular injury. Further studies are required to ascertain the usefulness of those biomarkers in early detection of AKI.

Prospective evaluation of 5 urinary biomarkers as predictors of acute kidney injury in nonazotemic, hospitalized dogs

BACKGROUND

Early recognition of acute kidney injury (AKI) is hindered by current definitions and use of traditional, insensitive markers.

HYPOTHESIS/OBJECTIVES

Urinary (u) activity of γ-glutamyl transpeptidase (GGT) and alkaline phosphatase (ALP), and concentrations of heat-shock protein 70 (HSP70) and interleukins (ILs) -6 and -18, are predictive biomarkers for AKI and survival.

ANIMALS

Nonazotemic, hospitalized dogs (n = 118) and healthy controls (n = 20).

METHODS

A prospective observational study. Nonazotemic dogs at risk of AKI were recruited and their urinary biomarker concentrations were measured at presentation. Serum creatinine (sCr) and symmetric dimethylarginine (sSDMA) were measured daily until discharge/death.

RESULTS

The overall case fatality rate was 18.6%. Fifteen dogs (12.7%) developed AKI, which was associated with death (relative risk, 3.2; 95% confidence interval [CI], 1.57-6.55). All 5 urinary biomarkers were significantly higher in hospitalized dogs compared to controls, with minimal overlap. uHSP70/uCr, uGGT/uCr, and uIL-6/uCr at presentation were higher in dogs which later developed AKI. Areas under the receiver operator characteristic curve (AUROC) (95% CI) for the 3 biomarkers as predictors of AKI were 0.67 (0.51-0.83), 0.68 (0.55-0.81), and 0.78 (0.65-0.91), respectively. When they were categorically classified as elevated/normal, each additional elevated biomarker increased the odds for AKI (OR, 2.83; 95% CI, 1.23-6.52, P = .01). Agreement between sCr and sSDMA was poor (Cohen's kappa = .071). The AUROC of SDMA at presentation for AKI prediction was 0.73 (0.51-0.95).

CONCLUSIONS AND CLINICAL IMPORTANCE

Kidney injury was common, irrespective of subsequent worsening of azotemia or death. The predictive value of individual urinary biomarkers was reduced by moderate sensitivities and specificities. SDMA showed moderate discriminatory utility for AKI prediction, and often displayed discordant results with sCr.

Conducting proportional meta-analysis in different types of systematic reviews: a guide for synthesisers of evidence

BACKGROUND

Single group data present unique challenges for synthesises of evidence. Proportional meta-analysis is becoming an increasingly common technique employed for the synthesis of single group data. Proportional meta-analysis shares many similarities with the conduct and reporting of comparative, or pairwise, meta-analysis. While robust and comprehensive methods exist detailing how researchers can conduct a meta-analysis that compares two (or more) groups against a common intervention, there is a scarcity of methodological guidance available to assist synthesisers of evidence in the conduct, interpretation, and importance of proportional meta-analysis in systematic reviews.

MAIN BODY

This paper presents an overview targeted to synthesisers of evidence and systematic review authors that details the methods, importance, and interpretation of a proportional meta-analysis. We provide worked examples of how proportional meta-analyses have been conducted in research syntheses previously and consider the methods, statistical considerations, and presentation of this technique.

CONCLUSION

This overview is designed to serve as practical guidance for synthesisers of evidence in the conduct of proportional meta-analyses.

Improved Cardiovascular Tolerance to Hemorrhage after Oral Resveratrol Pretreatment in Dogs

Resveratrol has been shown to preserve organ function and improve survival in hemorrhagic shock rat models. This study investigated whether seven days of oral resveratrol could improve hemodynamic response to hemorrhage and confer benefits on risk of acute kidney injury (AKI) without inducing coagulopathy in a canine model. Twelve greyhound dogs were randomly allocated to receive oral resveratrol (1000 mg/day) or placebo for seven days prior to inducing hemorrhage until a targeted mean blood pressure of ≤40 mmHg was achieved. AKI biomarkers and coagulation parameters were measured before, immediately following, and two hours after hemorrhage. Dogs were euthanized, and renal tissues were examined at the end of the experiment. All investigators were blinded to the treatment allocation. A linear mixed model was used to assess effect of resveratrol on AKI biomarkers and coagulation parameters while adjusting for volume of blood loss. A significant larger volume of blood loss was required to achieve the hypotension target in the resveratrol group compared to placebo group (median 64 vs. 55 mL/kg respectively, p = 0.041). Although histological evidence of AKI was evident in all dogs, the renal tubular injury scores were not significantly different between the two groups, neither were the AKI biomarkers. Baseline (pre-hemorrhage) maximum clot firmness on the Rotational Thromboelastometry (ROTEM^®) was stronger in the resveratrol group than the placebo group (median 54 vs. 43 mm respectively, p = 0.009). In summary, seven days of oral resveratrol did not appear to induce increased bleeding risk and could improve greyhound dogs’ blood pressure tolerance to severe hemorrhage. Renal protective effect of resveratrol was, however, not observed.

Analytical validation and reference intervals for a commercial multiplex assay to measure five novel biomarkers for acute kidney injury in canine urine

Novel urinary biomarkers are increasingly utilized for the diagnosis of acute kidney injury (AKI) in dogs. Magnetic-bead based immunoassays for the simultaneous measurement of multiple biomarkers represent a potentially efficient and cost effective tool for investigators; however there is limited data to support their reliable use in dogs. Analytical validation of a commercial multiplex assay for the measurement of five AKI biomarkers: clusterin, cystatin C, kidney-injury molecule 1 (KIM-1), monocyte chemoattractant protein 1 and neutrophil gelatinase-associated lipocalin (NGAL) in canine urine was performed. The effect of pre-analytical factors including potential interfering substances and sample storage methods were investigated. Urine from 110 healthy dogs was used to determine reference intervals for each biomarker measured, according to American Society of Veterinary Clinical Pathology guidelines. Additionally, urine from 21 dogs with pyuria was used to evaluate the impact of pyuria on biomarker concentration. The assay performed with acceptable accuracy and precision for the measurement of NGAL only. Clinically relevant urine concentrations of bilirubin, haemoglobin, and synthetic colloid solutions led to interference (mean percentage difference > +/- 15% compared to control) with measurement of all or some of the biomarkers. All biomarkers were stable in urine stored at 20-22 °C for 2 h, 4 °C for 12 h, or -20 °C for 6 months. Reference intervals could not be established for KIM-1 due to unacceptable measurement imprecision (intra- and inter assay coefficient of variation 45% and 20% respectively). Urine NGAL concentration was significantly elevated in pyuria (P < 0.001).

Effects of IV Fluids in Dogs and Cats With Kidney Failure

Intravenous fluid therapy has long been the mainstay of treatment of kidney disease, including acute kidney injury and uremic crisis associated with chronic kidney disease. Careful management of fluid dose is critical, as animals with kidney disease may have marked derangements in their ability to regulate fluid homeostasis and acid-base status. Understanding of the physiology of renal fluid handling is necessary, along with repeated attention to parameters of fluid status, electrolytes, and acid-base balance, to achieve optimal hydration status and avoid further damage or decrease in function from dehydration or overhydration.

Serial serum creatinine, SDMA and urinary acute kidney injury biomarker measurements in dogs envenomated by the European adder (Vipera berus)

Background

Acute kidney injury (AKI) is associated with high morbidity and mortality in dogs, but diagnosis may be impaired due the insensitivity of routine renal function biomarkers to detect earlier or milder forms of injury. Snake envenomation is one of several causes of AKI in dogs and humans. Dogs are commonly envenomated by the European adder (Vipera berus) between April and October each year, but few studies exist examining serial serum creatinine (sCr) and symmetric dimethylarginine (SDMA) measurements and AKI biomarkers in these dogs. Novel urinary biomarkers could improve clinical outcome by allowing earlier diagnosis of and intervention in AKI. The aim of this study was to assess the presence of AKI in dogs envenomated by V. berus at 12, 24 and 36 h after bite, as well as 14 days later, using sCr, SDMA and a panel of urinary AKI biomarkers normalised to urine creatinine (uCr), compared to a group of healthy control dogs.

Results

Thirty-five envenomated dogs and 35 control dogs were included. Serum creatinine did not exceed the upper reference limit at any time point in any dog after envenomation. Serum SDMA did not exceed 0.89 μmol/L in any dog. Compared to controls, urinary albumin/uCr, neutrophil gelatinase-associated lipocalin/uCr and monocyte chemotactic protein-1/uCr were significantly elevated 12 h (P <  0.0001, P <  0.0001, P = 0.01), 24 h (P <  0.001, P <  0.001, P = 0.002) and 36 h (P <  0.001, P <  0.001, P = 0.0008) after bite. Osteopontin/uCr was higher 24 and 36 h after bite (P < 0.0001), kidney injury molecule-1/uCr, interleukin-8/uCr and γ- glutamyl transferase/uCr were significantly higher 36 h after bite (P = 0.003, P = 0.0005, P = 0.001). Urinary cystatin C/uCr was not significantly different to controls at any timepoint. Biomarker/uCr ratios were not significantly different 14 days after envenomation compared to controls.

Conclusion

Urinary biomarker/Cr ratios are indicative of mild transient, non-azotaemic AKI in dogs envenomated by V. berus.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-02851-8.

Extracorporeal Therapies in the Emergency Room and Intensive Care Unit

Extracorporeal treatments create opportunity for removing disease causing solutes within blood. Intoxications, renal failure, and immune-mediated diseases may be managed with these treatments, often providing new hope for patients with severe or refractory disease. Understanding solute pharmacokinetics and the limitations of each type of extracorporeal technique can allow for the selection of the optimal treatment modality.

Immortalized canine adipose-derived mesenchymal stem cells alleviate gentamicin-induced acute kidney injury by inhibiting endoplasmic reticulum stress in mice and dogs

Adipose-derived mesenchymal stem cells have been used to treat acute kidney injury (AKI). The role of endoplasmic reticulum (ER) stress in AKI treatment with canine adipose-derived mesenchymal stem cells (cADSCs) remains unknown. This study intended to investigate the therapeutic effects of cADSCs cultured in different media on AKI in mice and dogs and reveal the role of ER stress in this process. The mice were divided into two branches: a control group and a gentamicin induced group (this group treated with low-serum ADSC or high-serum ADSC or 4-phenylbutyric acid (4-PBA)). The dogs were divided into control, model, and cell-injected groups. To suppress ER stress, mice were simultaneously treated with 4-PBA. The results showed there were improvements in renal function and tissue damage and a corresponding decrease in ER stress in the kidneys of the mice that received cell injection. However, the cells cultured with 2% FBS showed a better growth state and resulted in lower ER stress levels in treated kidneys. In the 4-PBA-treated group, ER stress was suppressed, and there was corresponding kidney injury recovery. Similarly, both kidney damage and ER stress were alleviated after AKI dogs were injected with the cells. Our findings reveal that both allogeneic and xenogeneic cADSCs were effective treatments for AKI by inhibiting ER stress. These results also provide evidence for a new clinical therapy for acute renal disease in pets.

Acute on chronic kidney disease in dogs: Etiology, clinical and clinicopathologic findings, prognostic markers, and survival

BACKGROUND

Chronic kidney disease (CKD) and acute exacerbation of CKD (ACKD) are common in dogs.

OBJECTIVE

To characterize the etiology, clinical and laboratory findings, and short- and long-term prognosis of dogs with ACKD.

ANIMALS

One hundred dogs with ACKD.

METHODS

Medical records of dogs diagnosed with ACKD admitted to a veterinary teaching hospital were retrospectively reviewed.

RESULTS

The most common clinical signs included anorexia (84%), lethargy (77%), vomiting (55%) and diarrhea (37%). Presumptive etiology included inflammatory causes (30%), pyelonephritis (15%), ischemic causes (7%), other (3%), or unknown (45%). Median hospitalization time was 5 days (range, 2-29 days) and was significantly longer in survivors (6 days; range, 2-29 days) compared with nonsurvivors (4 days; range, 2-20 days; P < .001). Mortality rate was 35%. International Renal Interest Society (IRIS) acute kidney injury (AKI) grade at presentation was associated (P = .009) with short-term survival, but presumptive etiology was not (P = .46). On multivariable analysis; respiratory rate (P = .01), creatine kinase (CK) activity (P = .005) and serum creatinine concentration (SCR; P = .04) at presentation were associated with short-term outcome. Median survival time of dogs discharged was 105 days (95% confidence interval [CI], 25-184), with 35 and 8 dogs surviving up to 6 and 12 months, respectively. Presumptive etiology (P = .16) and SCR (P = .59) at discharge were not predictors of long-term survival.

CONCLUSION AND CLINICAL IMPORTANCE

Short-term outcome of dogs with ACKD is comparable to those with AKI but long-term prognosis is guarded. The IRIS AKI grade at presentation is a prognostic indicator of short-term outcome.

Validation of a commercial magnetic bead-based multiplex assay for 5 novel biomarkers of acute kidney injury in canine serum

Interest is growing in measurement of novel biomarkers for the diagnosis of acute kidney injury. Multiplex assays may provide a rapid and cost-effective way of measurement; however, sparse information is published regarding their use in dogs. We aimed to validate a commercial magnetic bead-based assay for 5 biomarkers: clusterin (Clus), cystatin C (CysC), kidney injury molecule 1 (KIM-1), monocyte chemoattractant protein 1 (MCP-1), and neutrophil gelatinase-associated lipocalin (NGAL). Intra- and inter-assay imprecision, linearity under dilution (LUD), spike recovery (S-R), and hemoglobin interference were evaluated using serum from healthy and diseased dogs. Additionally, the effect of sample type (serum vs. plasma) was investigated. All values for Clus and MCP-1 were outside the assay's measurable range. Intra- and inter-assay precision were acceptable for NGAL (CVs 8.8% and 13.2%, respectively). Regression analysis of LUD and S-R indicated good linearity for CysC and NGAL. Hemolysis did not affect measurement of any biomarker. Measured concentrations of CysC (p = 0.018) and NGAL (p = 0.015) were significantly lower in sodium citrate plasma compared to serum. We conclude that this magnetic bead-based assay is precise and accurate for NGAL measurement in canine serum. Inappropriate standards for MCP-1 and Clus, and poor accuracy for KIM-1 measurement, suggest that this assay cannot reliably quantify those biomarkers in canine blood. Measurements of CysC in canine blood using this assay must be interpreted with caution given inter-assay imprecision.

Urine neutrophil gelatinase-associated lipocalin to diagnose and characterize acute kidney injury in dogs

BACKGROUND

Urine neutrophil gelatinase-associated lipocalin (NGAL) is a promising biomarker of acute kidney injury (AKI) in dogs.

OBJECTIVES

To evaluate the utility of urinary NGAL for characterizing AKI according to volume responsiveness, presence of inflammation and sepsis, and prognosis.

ANIMALS

Dogs with AKI (n = 76) and healthy controls (n = 10).

METHODS

Prospective study. Clinical and clinicopathologic data including absolute urine NGAL concentration (uNGAL) and NGAL normalized to urine creatinine concentration (uNGALC) were measured upon admission. Dogs were graded according to International Renal Interest Society (IRIS) AKI guidelines and compared based on AKI features: volume-responsive (VR-) AKI vs. intrinsic (I-) AKI based on IRIS criteria; VR-AKI and I-AKI based on urine chemistry; inflammatory versus noninflammatory; septic versus nonseptic; and survivors versus nonsurvivors. Nonparametric statistics were calculated, and significance set at P < .05.

RESULTS

Urinary NGAL was significantly higher in dogs with AKI compared to controls, regardless of AKI grade. Urinary NGAL did not differ between dogs with VR-AKI and I-AKI based on IRIS criteria, whereas higher uNGALC was recorded in dogs with I-AKI based on urine chemistry. Urinary NGAL was significantly higher in dogs with inflammatory AKI, whereas no difference with respect to sepsis or outcome was identified.

CONCLUSIONS AND CLINICAL IMPORTANCE

Urinary NGAL is a sensitive marker for AKI in dogs, but its specificity is affected by systemic inflammation. Increased urinary NGAL in both I-AKI and VR-AKI also suggests the presence of tubular damage in transient AKI. Combining urine chemistry data with IRIS criteria could facilitate AKI characterization in dogs.

Acute kidney injury management using intermittent low efficiency haemodiafiltration in a critical care unit: 39 dogs (2012-2015)

BACKGROUND

Veterinary studies describing acute kidney injury (AKI) management using renal replacement therapy (RRT) are limited and have primarily focused on intermittent haemodialysis in North American populations. European data are lacking, although differences in populations, pathogen and toxin exposure and RRT modalities may exist between Europe and North America. The present study reviewed RRT-managed cases from the intensive care unit (ICU) of VetAgro Sup, Lyon, France, for the period 2012-2015. The aims were to describe a 4-h RRT protocol of intermittent low efficiency haemodiafiltration, population characteristics and outcomes in canine AKI cases requiring RRT and to identify prognostic variables. We defined DeltaCreat/h as the difference between the serum creatinine level after RRT treatment N and that before treatment N + 1 divided by the time between treatments (in hours).

RESULTS

Thirty-nine dogs were included, and 67% were males. The median (range) age, weight, hospitalization length and number of RRT treatments were 4.4 (0.25-15) years, 26.6 (6.7-69) kg, 8 (1-23) days and 3 (1-8) treatments, respectively. The main AKI causes were leptospirosis (74.4%) and nephrotoxins (15.4%). Age (4.0 vs 5.4 years; P = 0.04), admission urine output (0.5 mL/kg/h vs 0 mL/kg/h; P = 0.02) and hospitalization length (10 vs 4 days; P < 0.001) differed between survivors and non-survivors. Hospitalization length [odds ratio (OR) = 0.4], number of treatments (OR = 5.1), serum potassium level on day 2 (OR = 1.9), DeltaCreat/h between the first and second treatments (OR = 1.2), and UOP during hospitalization (OR = 0.2) were correlated with outcome. The main causes of death were euthanasia (44%) and haemorrhagic diatheses (33%). The overall survival rate was 54%, with 55% of survivors discharged with a median creatinine < 240 µmol/L.

CONCLUSIONS

This is the first description in the veterinary literature of a 4-h protocol of intermittent low efficiency haemodiafiltration to provide RRT in a veterinary critical care unit. While this protocol appears promising, the clinical application of this protocol requires further investigation. Among parameters associated with survival, UOP and DeltaCreat/h between the first and second RRT treatments may be prognostic indicators. The applicability of these parameters to other populations is unknown, and further international, multicentre prospective studies are warranted to confirm these preliminary observations.