A retrospective study of acute kidney injury in cats and development of a novel clinical scoring system for predicting outcome for cats managed by hemodialysis

Evaluation of serum galectin-3 concentrations in healthy cats and in cats with ureteral obstruction

OBJECTIVES

Serum galectin-3 (sGal-3) is a protein present in renal tubules and increases in experimental rodent models of acute kidney injury. The aim of this study was to compare sGal-3 concentrations in healthy cats and cats with ureteral obstruction (UO).

METHODS

This was a retrospective study. Banked serum was used for sGal-3 evaluations in 15 healthy control cats and 22 cats with UO. For the control cats, creatinine and symmetric dimethylarginine were within reference intervals and ultrasound showed minimal to no kidney changes. A feline-specific sGal-3 ELISA was used to determine sGal-3 concentrations. Samples were analyzed in duplicate, and results were included if the coefficient of variation between samples was <20%. Shapiro-Wilk testing was used to evaluate for normality and parametric statistics were performed. P <0.05 was considered significant.

RESULTS

Mean (±SD) sGal-3 was lower in healthy cats (274.3 ± 146.5 pg/ml) than in cats with UO (707.7 ± 223.3 pg/ml; P <0.0001). There was no difference in sGal-3 concentrations between cats with unilateral or bilateral UO (P = 0.24) and no correlation between sGal-3 and creatinine, body weight or age. With a cutoff of 500 pg/ml, sGal-3 had a sensitivity of 86% (95% confidence interval [CI] 0.67-0.95) and specificity of 100% (95% CI 0.79-1.00) for differentiating cats with UO from healthy cats.

CONCLUSIONS AND RELEVANCE

An early diagnosis of UO is critical, given its associated morbidity and mortality. Given the differences in sGal-3 concentrations in healthy cats and those with UO in this study, sGal-3 shows potential for an early UO diagnosis; however, further research is needed.

Urinary Cystatin B as a marker of acute kidney injury in cats

Diagnosing acute kidney injury (AKI) might be challenging due to lack of sensitive early markers. The objective of this study was to evaluate the diagnostic and prognostic utility of the urinary biomarker Cystatin B (uCysB) in cats with AKI. Seventy-six client-owned cats were included. Urine samples of healthy cats and cats with various urinary tract disease including urethral obstruction (UO), chronic kidney disease (CKD) and AKI, were collected. uCysB concentration was measured using a research sandwich format ELISA at IDEXX Laboratories, Inc. uCysB was different among groups (P <0.001). uCysB was higher in the AKI (P <0.001) and CKD (P =0.006) groups compared with controls [1052 ng/mL (range, 7-3858) and 112 ng/mL (range, 14-1370) vs. 22 ng/mL (range, 11-154), respectively]. Cats with AKI had higher uCysB compared with cats with CKD (P =0.001) or UO (P =0.004). Receiver operator characteristic curve (ROC) analysis of uCysB as an AKI predictor vs. controls had an area under the curve (AUC) of 0.92 (95 % CI, 0.84-1.0). An 84 ng/mL cutoff point corresponded to sensitivity and specificity of 90 % and 92 %, respectively. uCysB concentration was higher in AKI non-survivors compared with survivors (1572 ng/mL, range, 140-3858 vs. 584 ng/mL, range, 7-2803 respectively; P =0.004). ROC analysis of uCysB as an AKI outcome predictor had an AUC of 0.84 (95 % CI, 0.56-1.0), with an optimal cut-off point of 469 ng/mL, corresponding to sensitivity and specificity of 100 % and 75 % respectively. In conclusion, uCysB is a useful diagnostic and prognostic marker of AKI in cats.

International renal interest society best practice consensus guidelines for intermittent hemodialysis in dogs and cats

Intermittent hemodialysis (IHD) is an advanced adjunctive standard of care for severe acute kidney injury (AKI) and other indications. Most animals with AKI are managed medically, however, when the disease is severe, medical management may not control the consequences of the disease, and animals with a potential for renal recovery may die from the consequences of uremia before recovery has occurred. Extracorporeal therapies aid the management of AKI by expanding the window of opportunity for recovery of sufficient kidney function to become dialysis independent. Intermittent hemodialysis (IHD) was introduced into veterinary medicine over 50 years ago, however, updated guidelines for the delivery of IHD have not been published for several decades. To that end, the International Renal Interest Society (IRIS) constituted a Working Group to establish best practice guidelines for the safe and effective delivery of IHD to animals with indications for dialytic intervention. The IRIS Working Group generated 60 consensus statements and supporting rational for a spectrum of prescription and management categories required for delivery of IHD on designated intermittent dialysis platforms (i.e., AKI, chronic hemodialysis and intoxications). A formal consensus method was used to validate the recommendations by a blinded jury of 12 veterinarians considered experts in extracorporeal therapies and actively performing IHD. Each vote provided a level of agreement for each recommendation proposed by the Working Group. To achieve a consensus, a minimum of 75% of the voting participants had to "strongly agree" or "agree" with the recommendation.

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.

The utility of clinicopathological findings and point-of-care ultrasound in increasing the index of suspicion of ureteral obstruction in azotaemic cats presenting to the emergency room

OBJECTIVES

Ureteral obstruction is a common post-renal cause of azotaemia in cats. The objective of this study was to describe clinicopathological and point-of-care ultrasound findings in azotaemic cats that may increase the index of suspicion of ureteral obstruction.

MATERIALS AND METHODS

A retrospective case-control study was conducted of azotaemic cats presenting to the emergency room of a referral teaching hospital. Cats were included if they were azotaemic and had point-of-care ultrasound and formal ultrasound performed. Cats were grouped into obstructed and non-obstructed groups based on formal specialist ultrasound and pyelography. Point-of-care ultrasound findings were described, including renal size and symmetry, renal pelvis dilation, perinephric fluid, and visualisation of the proximal ureter or calculi. Univariate analysis was performed to identify historical, biochemical and point-of-care ultrasound findings associated with ureteral obstruction before multivariate analysis.

RESULTS

One hundred twenty-two azotaemic cats met the inclusion criteria. Seventy-four cats were included in the obstructed azotaemic group and 48 cats in the non-obstructed azotaemic groups. Point-of-care ultrasound abnormalities were detected in 60 of 74 (81.1%) obstructed cats and 18 of 48 (37.5%) non-obstructed cats. Renal pelvis dilation (odds ratio 38.8; 95% confidence interval 2.9 to 515), hyporexia (odds ratio 5.9; 95% confidence interval 1.15 to 30.13), hypercalcaemia (odds ratio 16.6; 95% confidence interval 1.2 to 223.0) and hypokalaemia (odds ratio 21.7; 1.33 to 354.62) were more likely to be associated with ureteral obstruction than non-obstructive disease.

CLINICAL SIGNIFICANCE

Point-of-care ultrasound abnormalities are documented frequently in azotaemic cats with ureteral obstruction. Cats with renal pelvis dilation were 39 times more likely to have ureteral obstruction than non-obstructive acute kidney injury.

Do post-surgical multiresistant urinary infections occur in horses? Case of unilateral pyelonephritis caused by extended-spectrum beta-lactamase-producing bacteria as a complication of cystotomy

Pyelonephritis is a serious condition that is rarely described in horses. In contrast, urinary tract infections are common in humans and small animals, and multi-drug-resistant urinary infections are an emerging threat. In this report, we describe a horse with unilateral pyelonephritis caused by extended-spectrum beta-lactamase-producing bacteria belonging to the Enterobacter cloacae complex. [Correction added on 9 August 2023, after first online publication: The preceding sentence was corrected.] An 11-year-old Swedish warmblood gelding was diagnosed with a cystolith and a cystotomy through an open left para-inguinal approach was performed. Seven days after surgery the horse presented with pyrexia, dullness and colic. Diagnostic testing and renal transabdominal ultrasonography confirmed the presence of a right-sided pyelonephritis. Culture and antimicrobial susceptibility testing revealed a pure growth of extended-spectrum beta-lactamases-producing E. cloacae complex bacteria with resistance against beta-lactams, aminoglycoside and trimethoprim-sulphonamide classes. Treatment included prolonged oral antimicrobials according to susceptibility testing results (enrofloxacin), judicious use of non-steroidal anti-inflammatory drugs, fluid therapy and gastric ulcer prophylaxis. The horse recovered successfully and is currently in good health (follow-up of 5 years). Once the infection resolved, unilateral renal scarring occurred. Multidrug-resistant upper-urinary infections occur in horses and should be considered in a post-surgical patient that develops fever. Early diagnosis, urine bacterial culturing and antimicrobial susceptibility testing were crucial in this case to successful management.

Case report: Resolution of oligo-anuric acute kidney injury with furosemide administration in a cat following lily toxicity

Objective

To describe the successful outcome of a case of oligo-anuric acute kidney injury in a cat secondary to lily ingestion.

Case summary

A 12-week-old intact male domestic short-hair cat weighing 1.64 kg (3.6 lb) presented with a 12-h duration of vomiting and lethargy after exposure to lilies of the genera Lilium species 24 h prior to presentation. Severe azotemia (Creatinine 5.8 mg/dL, BUN > 100 mg/dL) and hyperkalemia (9.36 mmol/L) were noted on the day of presentation. Treatment of hyperkalemia was instituted with calcium gluconate, lactated ringers solution, dextrose, regular short-acting insulin, albuterol, and sodium bicarbonate, Oliguria to anuria was highly suspected based on a lack of urine production 21 h after hospitalization with intravenous fluid administration and a static bladder size. The cat was administered 4 mg/kg of furosemide, and urinated at 6 h following administration and continued to produce over 6 ml/kg/h of urine in the next 24 h. Two days following furosemide administration, the cat's hyperkalemia and azotemia resolved. The cat was discharged after 4 days of hospitalization, and a recheck revealed no persistent azotemia or hyperkalemia.

Unique information

Anuric acute kidney injury secondary to lily toxicity is associated with a poor prognosis, and the only treatment modality previously described is hemodialysis. The cat in this report was successfully managed with medical intervention and furosemide administration, with complete resolution of the acute kidney injury.

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 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.

Machine-learning algorithm as a prognostic tool in non-obstructive acute-on-chronic kidney disease in the cat

OBJECTIVES

The aim of this study was to develop an algorithm capable of predicting short- and medium-term survival in cases of intrinsic acute-on-chronic kidney disease (ACKD) in cats.

METHODS

The medical record database was searched to identify cats hospitalised for acute clinical signs and azotaemia of at least 48 h duration and diagnosed to have underlying chronic kidney disease based on ultrasonographic renal abnormalities or previously documented azotaemia. Cases with postrenal azotaemia, exposure to nephrotoxicants, feline infectious peritonitis or neoplasia were excluded. Clinical variables were combined in a clinical severity score (CSS). Clinicopathological and ultrasonographic variables were also collected. The following variables were tested as inputs in a machine learning system: age, body weight (BW), CSS, identification of small kidneys or nephroliths by ultrasonography, serum creatinine at 48 h (Crea48), spontaneous feeding at 48 h (SpF48) and aetiology. Outputs were outcomes at 7, 30, 90 and 180 days. The machine-learning system was trained to develop decision tree algorithms capable of predicting outputs from inputs. Finally, the diagnostic performance of the algorithms was calculated.

RESULTS

Crea48 was the best predictor of survival at 7 days (threshold 1043 µmol/l, sensitivity 0.96, specificity 0.53), 30 days (threshold 566 µmol/l, sensitivity 0.70, specificity 0.89) and 90 days (threshold 566 µmol/l, sensitivity 0.76, specificity 0.80), with fewer cats still alive when their Crea48 was above these thresholds. A short decision tree, including age and Crea48, predicted the 180-day outcome best. When Crea48 was excluded from the analysis, the generated decision trees included CSS, age, BW, SpF48 and identification of small kidneys with an overall diagnostic performance similar to that using Crea48.

CONCLUSIONS AND RELEVANCE

Crea48 helps predict short- and medium-term survival in cats with ACKD. Secondary variables that helped predict outcomes were age, CSS, BW, SpF48 and identification of small kidneys.

Kidney injury molecule-1 and urinary gamma-glutamyl transferase as biomarkers of acute kidney injury in cats

OBJECTIVES

To evaluate the concentration of kidney injury molecule-1 and activity of urinary gamma-glutamyl transferase in cats with urethral obstruction and healthy cats.

MATERIALS AND METHODS

Blood and urine samples were collected from a group of 15 healthy cats (control group) and a group of 20 cats with urethral obstruction at presentation, and 24 hours and 7 days after unblocking the obstruction. The serum creatinine, urinary creatinine and urinary gamma-glutamyl transferase were measured by spectrophotometry and kidney injury molecule-1 by the sandwich enzyme-linked immunosorbent assay.

RESULTS

On presentation, cats with obstruction had serum creatinine concentration and urinary gamma-glutamyl transferase index higher than healthy cats (mean difference 544 μmol/L, 95% confidence intervals 222 to 865 μmol/L, and 0.0022 U/μmol-uCre, 0.00043 to 0.0039 U/μmol-uCre, respectively), urine creatinine concentration lower (mean difference 25,624 µmol/L, 17,329 to 33,919 µmol/L), and no significant difference in the kidney injury molecule-1/urinary creatinine ratio (mean difference 13 pg/μmol-uCre, -33 to 59 pg/μmol-uCre). In the group of cats with urinary obstruction, over time serum creatinine decreased, urine creatinine increased, urinary gamma-glutamyl transferase index did not change significantly, and kidney injury molecule-1/urinary creatinine ratio increased.

CLINICAL SIGNIFICANCE

Cats with post-renal obstruction and potential intrinsic renal damage had higher urinary gamma-glutamyl transferase index than healthy cats at the time of presentation and showed increase in kidney injury molecule-1/urinary creatinine ratio over time.

Evaluation of and the prognostic factors for cats with big kidney-little kidney syndrome

BACKGROUND

The term big kidney-little kidney syndrome in cats has been used for many years, but the definitions are not consistent and relevant research is limited.

OBJECTIVE

To determine the factors that differ between normal and BKLK cats, as well as to develop models for predicting the 30-day survival of cats with ureteral obstruction (UO).

ANIMALS

Sixteen healthy cats and 64 cats with BKLK.

METHODS

Retrospective study. To define BKLK by reference to data from clinically healthy cats. The demographic and clinicopathological data among groups were statistically analyzed.

RESULTS

Big kidney-little kidney syndrome cats had higher blood urea nitrogen (BUN) (median [interquartile range] 69 [28-162] vs 21 [19-24] mg/dL, P < .001), creatinine (5.6 [1.9-13.3] vs 1.3 [1.05-1.40] mg/dL, P < .001), and white blood cells (10 800 [7700-17 500] vs 6500 [4875-9350] /μL, P < .001) and lower hematocrit (32.8 [27.1-38.4] vs 39.1 [38.1-40.4]%, P < .001), urine specific gravity (1.011 [1.009-1.016] vs 1.049 [1.044-1.057], P < .001) and pH (5.88 [5.49-6.44] vs 6.68 [6.00-7.18], P = .001) compared to the control cats. A lower body temperature (BT; 38.1 [37.9-38.2] vs 38.7 [38.3-39.2]°C, P = .009), higher BUN (189 [150-252] vs 91 [36-170] mg/dL, P = .04), and creatinine (15.4 [13.3-17.4] vs 9.0 [3.1-14.2] mg/dL, P = .03) were found among the UO cats that were not 30-day survivors. A combination of BUN, phosphorus, and BT can predict 30-day survival among UO cats with an area under receiver operating characteristic curve of 0.863. (P = .01).

CONCLUSION

An increase in the length difference between kidneys can indicate UO, but cannot predict outcome for BKLK cats.

Minimal renal pelvis dilation in cats diagnosed with benign ureteral obstruction by antegrade pyelography: a retrospective study of 82 cases (2012-2018)

OBJECTIVES

The aim of the study was to describe renal pelvis (RP) and ureteral ultrasonographic measurements in a population of cats with confirmed benign ureteral obstruction (UO) by antegrade pyelography. The secondary objective was to further describe clinical findings associated with minimally dilated obstructed kidneys in an attempt to better understand its occurrence.

METHODS

Retrospective case series of cats diagnosed with benign UO were confirmed by antegrade pyelography. Medical records were reviewed and signalment, diagnostic imaging results, serum creatinine (SCr) concentration and urine culture results were recorded. Each obstructed kidney was categorized into two groups: group 1 included all RP measurements ⩽4 mm and group 2 included all RP measurements >4 mm.

RESULTS

A total of 82 cats with 114 obstructed ureters met the inclusion criteria. Fifty (61%) cats had a unilateral UO and 32 (39%) had a bilateral UO. Thirty (26%) kidneys were included in group 1 while 84 (74%) were included in group 2. Nine (8%) kidneys had an RP dilation ⩽2 mm. Median RP and ureteral diameters were 6.6 mm (range 1.1-37.0 mm) and 3.2 mm (range 0.0-11.0 mm), respectively. RP size correlated positively with ureteral diameter in the study population (P <0.0001), but not in group 1 when analyzed separately (P = 0.47). UO was secondary to stones in 80 (70%) ureters. Seventeen (21%) cats had a positive urine culture. At admission, 79 (96%) cats were azotemic with a median preoperative SCr concentration of 444 µmol/l (range 108-1326 μmol/l). The mean (95% confidence interval [CI]) preoperative SCr concentration was significantly higher in group 1 (762 µmol/l [498-1165 μmol/l]) than in group 2 (409 µmol/l [333-502 μmol/l]). RP size in the two groups correlated negatively with preoperative SCr concentration (P = 0.0002).

CONCLUSIONS AND RELEVANCE

Feline UO may be associated with minimal RP dilation and the severity of RP and ureteral dilation can be highly variable. Absence of significant RP dilation does not rule out UO in cats.

Association of Veterinary Hematology and Transfusion Medicine (AVHTM) Transfusion Reaction Small Animal Consensus Statement (TRACS) Part 2: Prevention and monitoring

OBJECTIVE

To systematically review available evidence to develop guidelines for the prevention of transfusion reactions and monitoring of transfusion administration in dogs and cats.

DESIGN

Evidence evaluation of the literature (identified through Medline searches through Pubmed and Google Scholar searches) was carried out for identified transfusion reaction types in dogs and cats. Evidence was evaluated using PICO (Population, Intervention, Comparison, Outcome) questions generated for each reaction type. Evidence was categorized by level of evidence (LOE) and quality (Good, Fair, or Poor). Guidelines for prevention and monitoring were generated based on the synthesis of the evidence. Consensus on the final recommendations and a proposed transfusion administration monitoring form was achieved through Delphi-style surveys. Draft recommendations and the monitoring form were made available through veterinary specialty listservs and comments were incorporated.

RESULTS

Twenty-nine guidelines and a transfusion administration monitoring form were formulated from the evidence review with a high degree of consensus CONCLUSIONS: This systematic evidence evaluation process yielded recommended prevention and monitoring guidelines and a proposed transfusion administration form. However, significant knowledge gaps were identified, demonstrating the need for additional research in veterinary transfusion medicine.

Acute on chronic kidney disease in cats: Etiology, clinical and clinicopathologic findings, prognostic markers, and outcome

Background

Chronic kidney disease (CKD) and acute decompensation of CKD (ACKD) are common in cats.

Objectives

To characterize the etiology, clinical and clinicopathologic findings, and the short‐ and long‐term prognosis of feline ACKD.

Animals

One hundred cats with ACKD.

Methods

Retrospective study, search of medical records for cats with ACKD.

Results

Common clinical signs included anorexia (85%), lethargy (60%), weight loss (39%), and vomiting (27%). Suspected etiologies included ureteral obstruction (11%), renal ischemia (9%), pyelonephritis (8%), others (6%), or unknown (66%). Hospitalization duration was longer in survivors versus nonsurvivors (median = 7 days, range = 2‐26 versus median = 3 days, range = 2‐20, respectively, P < .001). The survival rate to discharge was 58%. Age, serum creatinine, urea, and phosphorous concentrations were higher and venous blood pH was lower in nonsurvivors. However, only serum phosphorus remained associated with the short‐term outcome in the multivariable model (P = .02; 95% confidence interval = 1.03‐1.39). Survivors had a median survival time of 66 days after discharge. Serum creatinine concentrations at presentation as well as at discharge were associated with long‐term survival (P < .002 for both).

Conclusions

The short‐term prognosis of ACKD is comparable to acute kidney injury, while the long‐term prognosis is guarded.

Renal expression and urinary excretion of liver-type fatty acid-binding protein in cats with renal disease

Background

Liver‐type fatty acid‐binding protein (L‐FABP) is a biomarker for early detection of renal disease in humans. Liver‐type fatty acid‐binding protein is cytotoxic oxidation products secreted from proximal tubules under ischemia and oxidative stress.

Objective

To examine renal expression and quantify urinary excretion of L‐FABP in catswith renal disease.

Animals

One hundred and thirty‐four client‐owned cats including 34 cats with serum creatinine (sCre) values >1.6 mg/dL and 10 other cats that died in clinics.

Methods

Tissue expressions of L‐FABP were examined by reverse transcription polymerase chain reaction and Western blotting. Urinary L‐FABP (uL‐FABP) and serum L‐FABP (sL‐FABP) levels were determined by enzyme‐linked immunosorbent assay. Anti‐liver‐type fatty acid‐binding protein antibody immunostained renal sections.

Results

Feline kidneys express L‐FABP. Strong L‐FABP signals were observed in the lumens of proximal tubular cells in 5 cats with high uL‐FABP excretion, but not in 5 cats with low uL‐FABP excretion. In 9 normal cats, uL‐FABP index was <1.2 μg/g urinary creatinine (uCre). High uL‐FABP indexes (>10.0 μg/g uCre) were detected in 7 of 100 cats with low sCre (<1.6 mg/dL) and 18 of 44 cats with high sCre (>1.6 mg/dL). There was a weak correlation between L‐FABP index and sCre, serum symmetric dimethylarginine (SDMA), or blood urea nitrogen (BUN), and these correlation coefficients were increased by analyzing only data of cats with sCre >1.6 mg/dL. There was a weak correlation between u L‐FABP index and sL‐FABP in all tested cats, but not in cats with high sCre.

Conclusions and Clinical Importance

This study demonstrates correlations between L‐FABP and current renal biomarkers for chronic kidney disease in cats, such as sCre and SDMA. Liver‐type fatty acid‐binding protein may be a potential biomarker to predict early pathophysiological events in feline kidneys.

A specific immunoassay for detection of feline kidney injury molecule 1

OBJECTIVES

The aim of this study was to design and carry out a preliminary evaluation of a urine point-of-care test for kidney injury molecule 1 (KIM-1) in healthy and diseased cats.

METHODS

Part of the feline KIM-1 gene was amplified, ligated into a plasmid with a signal peptide and monomeric human IgGFc, and transfected into a mammalian cell line. Supernatant was purified and tested for the fusion protein by gel electrophoresis and Western blot. Mice were immunized three times with purified proteins, and hybridomas were generated from splenocytes. Antibodies were tested by ELISA for detection of recombinant KIM-1 and naturally occurring KIM-1 in disease-state urine. Next, a lateral flow assay (LFA) with capture and detection antibodies was constructed, and tested with 34 urine samples from healthy and diseased cats. Antibodies were also tested for reactivity with formalin-fixed paraffin-embedded kidney tissue.

RESULTS

Three antibodies were assessed. Antibodies detected between 0.4 and 60 ng/ml feline KIM-1 fusion protein in the LFA. Urine samples from healthy cats yielded faint bands in the LFA corresponding to optical density (OD) values of 4.8-8.8. Samples from cats with suspected or confirmed acute kidney injury (AKI) had OD values ranging from 1.6-20.5. Urine KIM-1 varied over multiple days in cats with sepsis or urethral obstruction despite normalizing serum creatinine concentration. In tissue sections, KIM-1 antibodies labeled tubular cells with morphological features of injury.

CONCLUSIONS AND RELEVANCE

A practical patient-side assay for detection of KIM-1 in feline urine has been developed. Preliminary results show marked though transient increases in cats with sepsis and urethral obstruction-associated AKI, and expression in injured tubules. Although initial data indicating that the LFA is sensitive and specific for KIM-1 in cats with AKI are promising, values associated with different types of injury, urine collection, urine storage and specific gravity need to be investigated.

Contrast enhancement ultrasound of renal perfusion in dogs with acute kidney injury

OBJECTIVE

To evaluate the efficacy of contrast-enhanced ultrasound to assess changes in renal perfusion in dogs with acute kidney injury.

MATERIALS AND METHODS

The left kidney of each dog in two groups was examined using contrast-enhanced ultrasound: Group A consisted of 16 healthy dogs and Group B consisted of 12 dogs with acute kidney injury.

RESULTS

All dogs in Group A showed the same sequence of wash-in and wash-out. In Group B the distribution of contrast media showed a similar cortical phase to healthy dogs, but a faster time to maximal medullary enhancement. Group B showed increased medullary peak intensity and medullary area under the curve compared to Group A. Both qualitative and quantitative analyses showed vascular changes especially in the medulla, with more rapid medullary vascularisation and increased medullary perfusion. These results were interpreted as medullary congestion in dogs with acute kidney injury.

CLINICAL SIGNIFICANCE

Contrast-enhanced ultrasound represents an easy to perform, safe, and non-invasive method to detect changes in renal perfusion in dogs with acute kidney injury.

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.

Comparison of ultrasonographic findings in cats with and without azotaemia

Objectives The objective of this study was to identify the renal ultrasonographic (US) findings most strongly associated with azotaemia in cats. Methods US findings in 238 cats with (serum creatinine >180 μmol/l) and 270 cats without azotaemia were compared in a retrospective case-control study. Cats with pre-renal azotaemia or urethral obstruction were excluded. Data extracted from the medical records included age, body weight and body condition score (BCS). Quantitative and subjective US findings were extracted from archived ultrasound images and contemporaneous reports. Results In non-azotaemic cats, mean ± SD renal length was 40.1 ± 5.5 mm. Male cats had larger kidneys than female cats (mean difference 5.2 mm; P = 0.001) and, on average, the right kidney was slightly larger than the left (mean difference 1.6 mm; P = 0.01). Azotaemic cats had significantly lower mean body weight and BCS, and greater mean age and renal pelvic diameter. Renal pelvic diameter was negatively correlated with urine specific gravity (ρ -0.44, P <0.001). Compared with non-azotaemic cats, there was no difference in mean renal length of azotaemic cats because the numbers with enlarged kidneys and small kidneys were similar. Radiologists' subjective assessments of renal size differed markedly between azotaemic and non-azotaemic cats, with azotaemic cats more likely to be recorded falsely as having abnormally small or enlarged kidneys. US findings significantly associated with azotaemia were perinephric fluid (odds ratio [OR] 26.4, 95% confidence interval [CI] 3.4-207.7), small kidneys (OR 8.4, 95% CI 4.0-17.4), hyperechoic renal cortex (OR 4.1, 95% CI 2.2-7.6), loss of corticomedullary differentiation (OR 4.1, 95% CI 1.8-9.6), renal calculi (OR 2.7, 95% CI 1.4-4.9), enlarged kidneys (OR 2.5, 95% CI 1.2-5.5) and dilated renal pelvis (OR 1.6, 95% CI 1.3-1.9). Conclusions and relevance Perinephric fluid was the US finding most strongly associated with azotaemia in this study and may merit more emphasis than it has received to date. Bias in radiologists' subjective assessments of renal size suggests that other subjective findings will also be biased.

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

INTRODUCTION

Risk of mortality in the setting of acute kidney injury (AKI) in cats and dogs remains unclear.

OBJECTIVES

To evaluate the incidence of mortality in cats and dogs with AKI based on etiology (i.e. infectious versus non-infectious; receiving dialysis versus conservative treatment).

MATERIALS AND METHODS

Ovid Medline, EMBASE, and LILACS were searched up to July 2016. Articles were deemed eligible if they were case series studies evaluating the incidence of all-cause mortality in cats and dogs with AKI, regardless of etiology or the nature of treatment.

RESULTS

Eighteen case series involving 1,201animalsproved eligible. The pooled proportions for overall mortality were: cats53.1% [95% CI 0.475, 0.586; I2 = 11,9%, p = 0.3352]; dogs 45.0% [95% CI 0.33, 0.58; I2 = 91.5%, P < 0.0001]. A non-significant increase in overall mortality risk was found among dialysed animals relative to those managed with conservative treatment, independent of animal type and the etiology of their AKI. The pooled proportions for overall mortality according to etiology, regardless of treatment type, were: AKI due infectious etiology for cats and dogs, 19.2% [95% CI 0.134, 0.258; I2 = 37.7%, P = 0.0982]; AKI due non-infectious etiology for cats and dogs, 59.9% [95% CI 0.532, 0.663; I2 = 51.0%, P = 0.0211].

CONCLUSION

Our findings suggest higher rates of overall mortality in cats and dogs with AKI due to non-infectious etiologies relative to infectious etiologies, and showed non-significant differences in terms of higher rates associated with dialysis compared to conservative management. Further investigations regarding optimal time to initiate dialysis and the development of clinical models to prognosticate the course of disease and guide optimal treatment initiation for less severe cases of AKI in cats and dogs is warranted.

Ultrasonography in the diagnosis and management of cats with ureteral obstruction

Objectives The objective was to identify clinical or ultrasonographic results associated with ureteral obstruction or outcome in cats with azotaemia. Methods This was a retrospective cross-sectional study of cats with azotaemia (serum creatinine >180 μmol/l) that had ultrasonography of the urinary tract, ultrasound images available for review and received treatment for azotaemia. Cats with pre-renal azotaemia or urethral obstruction were excluded. Associations between clinical and ultrasonographic results and the dependent variables 'tentative diagnosis of ureteral obstruction', 'pyelography positive for ureteral obstruction' and 'death in hospital' were tested using binary logistic regression. Results In total, 238 cats satisfied the inclusion criteria. Median age was 7 years (range 2 weeks to 20 years), duration of clinical signs was 7 days (range 1 day to 6.3 years) and serum creatinine was 417 μmol/l (range 184-2100 μmol/l). Tentative diagnosis of ureteral obstruction in 92/238 (39%) cats was significantly associated with unilateral enlarged kidney on palpation, and dilated renal pelvis and calculi within the ureter on ultrasonography. Pyelography was performed in 49/92 (53%) cats (16 bilateral) with a tentative diagnosis of ureteral obstruction, and was positive for obstruction in 46/65 (71%) instances. No significant differences in ultrasonographic signs were found between cats with obstructed and non-obstructed ureters. Receiver-operating characteristic analysis of renal pelvic diameter as a diagnostic test for ureteral obstruction found an area under the curve not significantly different from 0.5. There was good agreement between results of radiography and ultrasonography for presence of urinary calculi (kappa 0.67). Treatment was medical in 171 (72%) cats and surgical (ureteral stent or by-pass device) in 67 (28%). Death in hospital was significantly associated with serum creatinine and presence of peritoneal fluid, but not with clinical diagnosis, ultrasonographic signs or treatment method. Conclusions and relevance Ultrasonography may be used to identify azotaemic cats at greatest risk of ureteral obstruction, but when using pyelography as the reference test ultrasonography appears to be inaccurate for diagnosis of ureteral obstruction.

Effect of tetrastarch (hydroxyethyl starch 130/0.4) on plasma creatinine concentration in cats: a retrospective analysis (2010-2015)

Objectives The objective was to determine survival and changes in creatinine concentrations after administration of 6% tetrastarch (hydroxyethyl starch [HES] 130/0.4) vs crystalloids in critically ill cats. Methods The medical records were reviewed for cats admitted to the intensive care unit with at least two plasma creatinine measurements and initial concentrations not exceeding the upper reference interval. Cats were excluded if they had received HES prior to admission or if they had received fluid therapy for <24 h between initial and subsequent measurements. Changes in creatinine concentrations were evaluated as the percentage change from initial values to the maximum subsequent measurements. Cats receiving only crystalloids were assigned to the crystalloid group; cats receiving only HES or HES and crystalloids were assigned to the HES group. Results Ninety-three cats were included in the study (62 in the crystalloid group, 31 in the HES group). The total median cumulative HES dose was 94 ml/kg (range 26-422 ml/kg) and 24 ml/kg/day (range 16-42 ml/kg/day). No difference was detected between the groups for age, sex, body weight or mortality. The HES group had a significantly longer length of hospitalisation ( P = 0.012), lower albumin concentrations ( P <0.001), higher Acute Patient Physiologic and Laboratory Evaluation scores ( P = 0.037) and higher incidence of systemic inflammatory response syndrome ( P = 0.009) and sepsis ( P = 0.013). There was no significant difference in initial, maximum or maximum change in creatinine concentrations between the groups. Moreover, there was no significant difference in maximum change in creatinine concentrations in the subgroups of cats with systemic inflammatory response syndrome or sepsis. Conclusions and relevance In this population of cats, the administration of HES did not result in a significantly greater increase in creatinine from values measured on admission or higher mortality compared with administration of crystalloids. Further prospective studies are needed to assess both safety and efficacy of HES in cats before recommendations can be made.

Expression of Kidney Injury Molecule-1 in Healthy and Diseased Feline Kidney Tissue

Sensitive markers to detect acute kidney injury (AKI) in cats are lacking. Kidney injury molecule-1 (KIM-1) is a promising marker of acute tubular injury in humans, and sequence and structure of feline KIM-1 have been determined. KIM-1 is shed into urine of cats with natural AKI. The objectives of this study were to characterize temporal and cellular expression of KIM-1 in kidneys from cats without and with experimental and natural AKI using histopathology and immunohistochemistry. Tissue sections from 8 cats without kidney disease, 3 to 4 cats with experimentally induced AKI on each day 1, 3, 6, and 12 after unilateral ischemia/reperfusion, and 9 cats with natural AKI were assessed. In sections from cats without kidney disease, patterns of periodic acid–Schiff and aquaporin-1 staining allowed identification of 3 distinct segments of the proximal tubule. KIM-1 staining was absent in segments 1 (S1) and S2, and faint in S3. Injury of S3 in cats with experimental and natural AKI was characterized by cell loss and necrosis, and remaining intact cells had cytoplasmic blebs and reduced brush borders. In experimental AKI, intensity of KIM-1 expression increased in proportion to the severity of injury and was consistently present in S3 but only transiently in other segments. Vimentin was absent in proximal tubules of healthy cats but expressed in injured S3. These findings indicate that S3 is the proximal tubular segment most susceptible to ischemic injury and that KIM-1 is a sensitive tissue indicator of AKI in cats.

Impact of feline AIM on the susceptibility of cats to renal disease

Renal failure is one of the most important social problems for its incurability and high costs for patients’ health care. Through clarification of the underlying mechanism for the high susceptibility of cats to renal disease, we here demonstrates that the effective dissociation of serum AIM protein from IgM is necessary for the recovery from acute kidney injury (AKI). In cats, the AIM-IgM binding affinity is 1000-fold higher than that in mice, which is caused by the unique positively-charged amino-acid cluster present in feline AIM. Hence, feline AIM does not dissociate from IgM during AKI, abolishing its translocation into urine. This results in inefficient clearance of lumen-obstructing necrotic cell debris at proximal tubules, thereby impairing AKI recovery. Accordingly, mice whose AIM is replaced by feline AIM exhibit higher mortality by AKI than in wild-type mice. Recombinant AIM administration into the mice improves their renal function and survival. As insufficient recovery from AKI predisposes patients to chronic, end-stage renal disease, feline AIM may be involved crucially in the high mortality of cats due to renal disease. Our findings could be the basis of the development of novel AKI therapies targeting AIM-IgM dissociation, and may support renal function in cats and prolong their lives.

Hypothermia in Uremic Dogs and Cats

BACKGROUND

The prevalence of uremic hypothermia (UH) and the effects of improving uremia on body temperature have not been determined in veterinary patients.

OBJECTIVES

To determine the prevalence of UH and correlations between uremia and body temperature in patients undergoing intermittent hemodialysis (IHD).

ANIMALS

Uremic dogs (n = 122) and cats (n = 79) treated by IHD at the Bobst Hospital of the Animal Medical Center from 1997 to 2013.

METHODS

Retrospective review of medical records.

RESULTS

The prevalence of hypothermia was 38% in azotemic cats and 20.5% in azotemic dogs. Statistically significant temperature differences were observed between uremic and nonuremic dogs (nonuremic: mean, 100.8°F; range, 91.2-109.5°F; uremic: mean, 99.9°F; range, 95.6-103.8°F; P < .0001) and cats (nonuremic: mean, 100.6°F; range, 94.0-103.8°F; uremic: mean, 99.3°F; range, 92.3-103.4°F; P < .0001). In dog dialysis patients, significant models included (1) timing (pre-dialysis versus post-dialysis) with weight class (small [P < .0001], medium [P = .016], and large breed [P = .033] dogs), (2) timing with serum creatinine concentration (P = .021), and (3) timing with BUN concentration (P < .0001). In cat dialysis patients, there was a significant interaction between timing and weight as a categorical variable (<5 kg and ≥5 kg).

CONCLUSIONS AND CLINICAL IMPORTANCE

Uremic hypothermia appears to be a clinical phenomenon that occurs in cats and dogs. Uremic patients are hypothermic compared to ill nonuremic patients and body temperatures increase when uremia is corrected with IHD in dogs and in cats >5 kg. In cats, UH seems to be a more prevalent phenomenon driven by uremia. Uremic hypothermia does occur in dogs, but body weight is a more important predictor of body temperature.

Kidney Disease and the Nexus of Chronic Kidney Disease and Acute Kidney Injury: The Role of Novel Biomarkers as Early and Accurate Diagnostics

Chronic kidney disease (CKD) and acute kidney injury (AKI) are interconnected and the presence of one is a risk for the other. CKD is an important predictor of AKI after exposure to nephrotoxic drugs or major surgery, whereas persistent or repetitive injury could result in the progression of CKD. This brings new perspectives to the diagnosis and monitoring of kidney diseases highlighting the need for a panel of kidney-specific biomarkers that reflect functional as well as structural damage and recovery, predict potential risk and provide prognosis. This article discusses the kidney-specific biomarkers, symmetric dimethylarginine (SDMA), clusterin, cystatin B, and inosine.

Urinary Neutrophil Gelatinase-associated Lipocalin as a Marker for Identification of Acute Kidney Injury and Recovery in Dogs with Gentamicin-induced Nephrotoxicity

BACKGROUND

Acute kidney injury (AKI) is associated with high mortality rates in dogs, which may be a consequence of late recognition using traditional diagnostic tests. Neutrophil gelatinase-associated lipocalin (NGAL) is a protein-induced during kidney injury that may identify AKI earlier than traditional tests.

OBJECTIVES/HYPOTHESIS

To evaluate urinary NGAL (uNGAL) and uNGAL-to-urinary creatinine ratio (UNCR) as early markers of kidney injury and recovery in an AKI model in dogs. It was hypothesized that these markers would document AKI earlier than serum creatinine concentration.

ANIMALS

Five purpose-bred dogs.

METHODS

Prospective study. Acute kidney injury, defined as a > 50% increase in serum creatinine concentration above baseline, was induced in dogs by gentamicin administration (8-10 mg/kg SC q8h). Blood and urine collected for biochemical analyses and uNGAL and urinary creatinine concentrations, respectively, during AKI induction and recovery.

RESULTS

Acute kidney injury was diagnosed significantly earlier based on a 7-fold increase in UNCR compared to a > 50% increase in serum creatinine concentration (day 8; range, 2-10 mg/dl vs day 16; range, 14-19 mg/dl; P = .009). During recovery, the initial decrease in UNCR preceded the decrease in serum creatinine concentration by a median of 2 days. The uNGAL changes paralleled UNCR changes, but the increase in uNGAL was triphasic; the initial peak occurred earlier than UNCR (median, day 11 versus median, day 19).

CONCLUSIONS AND CLINICAL IMPORTANCE

The UNCR was early marker of gentamicin-induced AKI and its decrease documented onset of renal recovery. Additional studies are needed to validate this marker in dogs with naturally occurring renal injury.

Unilateral Renal Ischemia as a Model of Acute Kidney Injury and Renal Fibrosis in Cats

The objectives of this study were to define the acute and chronic effects of 1-hour unilateral in vivo renal ischemia on renal function and histology in cats. Twenty-one adult purpose-bred research cats were anesthetized, and 1 kidney underwent renal artery and vein occlusion for 1 hour. Serum creatinine and urea concentrations, urine protein:creatinine ratio, urine-specific gravity, glomerular filtration rate, hematocrit, platelet concentration and function, and white blood cell count were measured at baseline and variable time points after ischemia. Renal histopathology was evaluated on days 3, 6, 12, 21, 42, and 70 postischemia; changes in smooth muscle actin and interstitial collagen were examined. Following ischemia, whole animal glomerular filtration rate was significantly reduced (57% of baseline on day 6; P < .05). At the early time points, the ischemic kidneys exhibited severe acute epithelial necrosis accompanied by evidence of regeneration of tubules predominantly within the corticomedullary junction. At later periods, postischemic kidneys had evidence of tubular atrophy and interstitial inflammation with significantly more smooth muscle actin and interstitial collagen staining and interstitial fibrosis when compared with the contralateral control kidneys. This study characterizes the course of ischemic acute kidney injury in cats and demonstrates that ischemic acute kidney injury triggers chronic fibrosis, interstitial inflammation, and tubular atrophy in feline kidneys. These late changes are typical of those observed in cats with naturally occurring chronic kidney disease.

Characterization of kidney injury molecule-1 in cats

BACKGROUND

Kidney disease (KD) is common in older cats and presumed to arise from subclinical kidney injuries throughout life. Sensitive markers for detecting kidney injury are lacking. Kidney injury molecule 1 (KIM-1) is a useful biomarker of kidney injury in humans and rodents.

HYPOTHESIS/OBJECTIVES

Feline KIM-1 is conserved across species, expressed in kidney, and shed into urine of cats with acute kidney injury (AKI). The objectives were to characterize the feline KIM-1 gene and protein, assess available immunoassays for detecting KIM-1 in urine of cats, and identify KIM-1 expression in kidney sections.

ANIMALS

Samples from 36 hospitalized and 7 clinically healthy cats were evaluated. Hospitalized cats were divided into 2 groups based on absence (n = 20) or presence (n = 16) of historical KD.

METHODS

Feline KIM-1 genomic and complementary DNA sequences were amplified, sequenced and analyzed to determine the presence of isoforms, exon-intron organization and similarity with orthologous sequences. Presence in urine was evaluated by immunoassay and expression in kidney by immunohistochemistry.

RESULTS

Three expressed feline KIM-1 transcript variants comprising 894, 810, and 705 bp were identified in renal tissue. KIM-1 immunoassays yielded positive results in urine of cats with conditions associated with AKI, but not chronic KD. Immunohistochemistry of kidney sections identified KIM-1 in proximal tubular cells of cats with positive urine immunoassay results.

CONCLUSIONS AND CLINICAL IMPORTANCE

Kidney injury molecule 1 was expressed in specific segments of the nephron and detected in urine of cats at risk of AKI. Urine KIM-1 immunoassay may be a useful indicator of tubular injury.

Management of acute kidney injury with continuous venovenous haemodiafiltration in a cat

Continuous renal replacement therapy is an emerging technique for the treatment of acute kidney injury (AKI). Data regarding its use in cats are limited. This report describes the use of a novel continuous renal replacement therapy (CRRT) system for the treatment of AKI in a cat. A 1.3-year-old cat developed uraemic signs following the administration of a non-steroidal anti-inflammatory agent for the treatment of a suspect traumatic episode. CRRT was provided with a Prismaflex Gambro machine used in continuous venovenous haemodiafiltration mode, with an AN-69 surface-treated membrane, synthetic colloid priming and heparin anticoagulation. Two treatment cycles were performed, totalling 51 h of CRRT. The treatment was effective in controlling uraemic signs, and no major complications were noted. Owing to financial constraints the owners declined further CRRT treatments, and on day 8 of hospitalisation, owing to the lack of significant clinical improvement, humane euthanasia was performed. The set-up detailed in this report provides a viable option for the initial treatment of cats with AKI.

ASSOCIATIONS BETWEEN ULTRASOUND AND CLINICAL FINDINGS IN 87 CATS WITH URETHRAL OBSTRUCTION

Urethral obstruction is a life-threatening form of feline lower urinary tract disease. Ultrasonographic risk factors for reobstruction have not been previously reported. Purposes of this retrospective cross-sectional study were to describe urinary tract ultrasound findings in cats following acute urethral obstruction and determine whether ultrasound findings were associated with reobstruction. Inclusion criteria were a physical examination and history consistent with urethral obstruction, an abdominal ultrasound including a full evaluation of the urinary system within 24 h of hospitalization, and no cystocentesis prior to ultrasound examination. Medical records for included cats were reviewed and presence of azotemia, hyperkalemia, positive urine culture, and duration of hospitalization were recorded. For medically treated cats with available outcome data, presence of reobstruction was also recorded. Ultrasound images were reviewed and urinary tract characteristics were recorded. A total of 87 cats met inclusion criteria. Common ultrasound findings for the bladder included echogenic urine sediment, bladder wall thickening, pericystic effusion, hyperechoic pericystic fat, and increased urinary echoes; and for the kidneys/ureters included pyelectasia, renomegaly, perirenal effusion, hyperechoic perirenal fat, and ureteral dilation. Six-month postdischarge outcomes were available for 61 medically treated cats and 21 of these cats had reobstruction. No findings were associated with an increased risk of reobstruction. Ultrasonographic perirenal effusion was associated with severe hyperkalemia (P = 0.009, relative risk 5.75, 95% confidence interval [1.54-21.51]). Findings supported the use of ultrasound as an adjunct for treatment planning in cats presented with urethral obstruction but not as a method for predicting risk of reobstruction.

Retrospective study of the perioperative management and complications of ureteral obstruction in 37 cats

OBJECTIVES

To describe perioperative management and complications, risk factors and mortality rates in cats anaesthetized for treatment of ureteral obstruction.

STUDY DESIGN

Retrospective, clinical, cohort study.

ANIMALS

Thirty-seven client-owned cats anaesthetized for ureteral surgery.

METHODS

Records with sufficient data for cats treated between March 2010 and March 2013 were examined for breed, age, gender, history, concurrent diseases, pre- and post-anaesthetic biochemical and haematological parameters, American Society of Anesthesiologists classification, anaesthetic protocol, surgical technique, surgeon, perioperative complications and mortality within 48 hours after extubation. Associations between risk factors and outcome variables were evaluated using univariable analysis. Odds ratios and 95% confidence intervals were calculated for significant parameters. Sensitivity and specificity using receiving operator characteristic curve analysis were calculated for creatinine, potassium level and standard base excess (SBE) to denote survival or non-survival.

RESULTS

Preoperatively, all cats were azotaemic: mean±SD urea was 31.6 ± 26.9 mmol L(-1) and median (range) creatinine was 562 μmol L(-1) (95 μmol L(-1) to off scale). Thirteen cats were hyperkalaemic (K+ 6.5 mmol L(-1)). Anaesthesia-related complications included bradycardia (n=8, 21.6%), hypotension (n=15, 40.5%) and hypothermia (n=32, 86.5%). Seven cats (18.9%) died postoperatively. Non-survivors were significantly (p=0.011) older (9.8±1.9 years) than survivors (6.4±3.1 years) and had higher potassium concentrations (p=0.040). Risk factors associated with mortality were ASA classes IV and V (p=0.022), emergency procedures (p=0.045) and bicarbonate administration (p=0.002). Non-survivors had higher creatinine concentrations (p=0.021) and lower SBE (p=0.030).

CONCLUSION AND CLINICAL RELEVANCE

Intraoperative anaesthetic complications were common; increased age, poor health status, preoperative bicarbonate administration, hyperkalaemia and increased creatinine were associated with increased risk for death and can be used to predict risk for complications.