Hemogram-Derived Inflammatory Markers in Cats with Chronic Kidney Disease

Chronic kidney disease (CKD) is characterized by chronic inflammation, which mediates the progressive replacement of functional nephrons by fibrotic tissue. Hemogram-derived inflammatory markers are known to serve as markers of pathological conditions; however, their diagnostic value in feline CKD is still unknown. The aim of this retrospective study was to investigate selected hemogram-derived inflammatory markers (neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyte ratio (PLR) and the systemic immune-inflammatory index (SII)) in cats at different clinical stages of CKD. Eighty-eight client-owned cats with CKD and thirty-two healthy control cats were included. Cats with CKD were divided into two groups: early CKD (IRIS stage 1 and 2; 62 cats) and progressed CKD (IRIS stage 3 and 4; 26 cats). The values of inflammatory markers were compared between the two CKD groups and the control group. All investigated hemogram-derived inflammatory markers were significantly (p < 0.05) greater in cats with advanced CKD than in those in the other two groups. Additionally, we demonstrated a statistically significant weak to moderate correlation between serum urea, creatinine, selected hematologic and urinary parameters, and the investigated inflammatory markers in cats with CKD. Chronic inflammation can be easily and inexpensively assessed with hemogram-derived markers.

2024 ISFM and AAFP consensus guidelines on the long-term use of NSAIDs in cats

PRACTICAL RELEVANCE

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used and are effective for the management of pain in cats. These Guidelines will support veterinarians in decision-making around prescribing NSAIDs in situations of chronic pain, to minimise adverse effects and optimise pain management. Information is provided on mechanism of action, indications for use, screening prior to prescription, use in the presence of comorbidities, monitoring of efficacy, and avoidance and management of adverse effects.

CLINICAL CHALLENGES

The cat's unique metabolism should be considered when prescribing any medications, including NSAIDs. Chronic pain may be challenging to detect in this species and comorbidities, particularly chronic kidney disease, are common in senior cats. Management of chronic pain may be complicated by prescription of other drugs with the potential for interactions with NSAIDs.

EVIDENCE BASE

These Guidelines have been created by a panel of experts brought together by the International Society of Feline Medicine (ISFM) and American Association of Feline Practitioners (AAFP). Information is based on the available literature, expert opinion and the panel members' experience.

Decreased circulating transforming growth factor-beta (TGF-β) and kidney TGF-β immunoreactivity predict renal disease in cats with naturally occurring chronic kidney disease

OBJECTIVES

The aim of the present study was to compare the circulating transforming growth factor-beta (TGF-β) of clinically normal age-matched and naturally occurring chronic kidney disease (CKD) cats and to determine the correlation between the TGF-β expression and histopathological changes in cats with CKD.

METHODS

A total of 11 clinically normal age-matched and 27 cats with naturally occurring CKD were included in this study. Circulating TGF-β was quantified by immunoassays. Kaplan-Meier analysis was used to calculate the association between survival time and the concentration of circulating TGF-β. A general linear model was used to compare the circulating TGF-β between groups. Immunohistochemical analyses revealed TGF-β expression in renal tissues from cats with CKD that died during the study (n = 7) and in available archived renal tissue specimens taken at necropsy from cats that had previous CKD with renal lesions (n = 10). Correlations of the TGF-β expression and clinical parameters (n = 7) and histopathological changes (n = 17) were analysed using Spearman's rank correlation.

RESULTS

The median survival time of cats with a lower concentration of circulating TGF-β was shorter than that of cats with a higher concentration. The area under the curve of circulating TGF-β for predicting CKD was 0.781, indicating good differentiation. The study indicated a significant difference in circulating TGF-β concentrations between clinically normal cats and those with CKD and demonstrated that TGF-β expression is correlated with tubular atrophy.

CONCLUSIONS AND RELEVANCE

The study findings suggest that decreased serum TGF-β and tubular atrophy with TGF-β immunoreactivity may be significant in cats with CKD.

Clinical management of feline chronic kidney disease in Portugal: a questionnaire-based study

OBJECTIVES

The aim of the study was to characterise the clinical management of feline chronic kidney disease (CKD) by veterinary practitioners in Portugal.

METHODS

A questionnaire-based study was designed to be completed by all veterinarians who had diagnosed and treated at least one case of feline CKD in the previous year.

RESULTS

A total of 409 veterinary practitioners responded to the questionnaire, with approximately half of them diagnosing 2-5 cases of feline CKD per month (n = 219, 53.5%). Although a high proportion of these reported using the guidelines published by the International Renal Interest Society (n = 379, 92.7%), only 19.1% (n = 78) systematically performed systolic blood pressure (SBP) measurements in all of their patients. A renal diet was advised by almost all respondents (n = 406, 99.3%), but 36.9% (n = 150) of them considered that it represented less than 75% of the daily food intake for most of their patients. This dietary intervention was often prescribed regardless of stage (n = 298, 73.4%) and without a proper gradual diet transition. Appetite stimulants were frequently prescribed (n = 366, 89.5%), as well as a calcium channel blocker (n = 171, 41.8%) and an angiotensin-converting enzyme inhibitor (n = 245, 59.9%) to control systemic hypertension and proteinuria, respectively. Prescription of a phosphate binder was also common (n = 311, 76.0%). Regarding monitoring, 70.9% (n = 290) recommended that stable patients be reassessed every 2-3 months or more frequently, but only 35.7% (n = 146) were able to comply with this periodicity due to owners' constraints.

CONCLUSIONS AND RELEVANCE

The findings showed that although most survey respondents are aware of international guidelines for the clinical management of cats with CKD, the SBP measurement still needs to be more systematic to allow proper substaging and detection of systemic hypertension. The monitoring frequency was lower than recommended. Furthermore, the introduction of a renal therapeutic diet should be refined to improve its acceptance rate.

Adeno-associated virus-vectored erythropoietin gene therapy for anemia in cats with chronic kidney disease

BACKGROUND

A treatment of chronic kidney disease (CKD)-associated anemia in cats is needed. SB-001 is an adeno-associated virus-vectored (AAV)-based gene therapeutic agent that is administered intramuscularly, causing the expression of feline erythropoietin.

HYPOTHESIS/OBJECTIVE

We hypothesized that SB-001 injection would lead to a sustained increase in PCV in cats with CKD-associated anemia.

ANIMALS

Twenty-three cats with International Renal Interest Society (IRIS) Stage 2 to 4 CKD-associated anemia were enrolled at 4 veterinary clinics.

METHODS

In a prospective clinical trial, cats were treated with 1 of 3 regimens of SB-001 (Lo 1.2 × 109 genome copies [GCs] on Day 0; Lo ± Hi [supplemental 2nd dose of 3.65 × 109 GC on Day 42]; Hi 3.65 × 109 GC IM on Day 0) and followed for 70 days.

RESULTS

A response to SB-001 at any time between Day 28 and Day 70 was seen in 86% (95% confidence interval 65, 97%) of all cats. There was a significant (P < .003) increase in PCV from Day 0 to Day 28 (mean increase 6 ± 6 percentage points [pp]; n = 21), Day 42 (8 ± 9 pp; n = 21), Day 56 (10 ± 11 pp; n = 17), and Day 70 (13 ± 14 pp, n = 14). Twelve cats were hypertensive at baseline, 4 of which developed encephalopathy during the study. An additional 6 cats became hypertensive during the study.

CONCLUSIONS AND CLINICAL IMPORTANCE

Results of this study suggest that SB-001 therapy represents a suitable single injection treatment that can address nonregenerative anemia in cats with CKD. It was generally well tolerated; however, hypertension and encephalopathy developed in some cats as previously described in association with erythropoiesis-stimulating agent therapy.

Determination of age-specific reference intervals for selected serum and urinary biomarkers in elderly cats

OBJECTIVES

Annual health screening is recommended in elderly cats to allow the early detection of conditions such as chronic kidney disease (CKD) and hyperthyroidism. Nevertheless, age-specific reference intervals (RIs) for renal and thyroid parameters in this population are lacking. The aim of this study was to determine age-specific RIs for selected serum and urine biomarkers related to CKD and hyperthyroidism, namely serum creatinine (sCr), symmetric dimethylarginine (SDMA), phosphate (P), total calcium (tCa), total thyroxine (TT4), urinary protein:creatinine ratio (UPC) and urine specific gravity (USG). These RIs were established for elderly cats (aged ⩾7 years) in general, as well as for mature adult cats (aged 7-10 years) and senior cats (aged >10 years) separately.

METHODS

A prospective study was conducted on client-owned cats aged ⩾7 years and considered healthy by their owners. The cats were screened to rule out metabolic and systemic diseases by means of a thorough history, complete physical examination, blood examination and urinalysis. The data from 206 healthy elderly cats (134 mature adult and 72 senior cats) were included. Age-appropriate RIs were determined following the guidelines of the American Society of Veterinary Clinical Pathology and compared with existing laboratory RIs.

RESULTS

Clinically relevant differences between the age-specific RI and the laboratory RI were found for several variables. Compared with the laboratory RI, the upper limit of the RI for cats aged ⩾7 years was lower for sCr, TT4 and P, and higher for SDMA. The lower limit of the age-appropriate RI was lower for USG. The new RI was almost identical to the existing laboratory RI for tCa and UPC.

CONCLUSIONS AND RELEVANCE

Using age-specific RIs for renal and thyroid biomarkers in mature adult and senior cats has important clinical consequences for the interpretation of health screening results in elderly cats. This confirms the need to adapt laboratory RIs to the specific animal population for which the RI will be used.

Beraprost and Overall Survival in Cats with Chronic Kidney Disease

BACKGROUND

Overall survival is the most important outcome for treatment response in feline chronic kidney disease (CKD). Beraprost has been shown to reduce the kidney function decline in cats with International Renal Interest Society (IRIS) stage 2 and 3 CKD. However, the association with prolonged survival has not yet been examined.

OBJECTIVE

To assess the relationship between beraprost and overall survival in cats with CKD in real clinical practice.

ANIMALS

Client-owned cats with IRIS stage 3 CKD (n = 134) were evaluated between 2017 and 2020.

METHODS

A retrospective cohort study based on data from electronic medical records of one hospital.

RESULTS

The cohort was divided into "beraprost therapy" and "no beraprost therapy" groups, and survival analyses revealed that overall survival was significantly longer in the beraprost therapy group, using Kaplan-Meier curves (p = 0.004). However, baseline phosphate is known to be an important prognostic indicator and was not well balanced between the two groups. Therefore, a subcohort of 97 cats was selected (those having baseline phosphate <6.0 mg/dL) that allowed for this parameter to be balanced between groups. The survival data in this subcohort were consistent with those of the overall study cohort.

CONCLUSIONS

In feline patients with CKD, beraprost therapy is associated with better overall survival.

Feline ureteral rupture with para-ureteral urinomas following blunt trauma: clinical presentation and long-term outcome after treatment by urinary diversion for five cases from 2012 to 2019

CASE HISTORY

Medical records were reviewed for cats that underwent surgical treatment of traumatic ureteral rupture (TUR) using urinary diversion procedures between 2012 and 2019.

CLINICAL FINDINGS AND TREATMENT

Five cats had presented with injuries associated with road traffic accidents. These included three cats with abdominal hernias that required surgical management. At a median of 15 days after the accident, cats represented with lethargy, the presence of an abdominal mass or with lower urinary tract symptoms and in all cats contrast diagnostic imaging showed proximal unilateral TUR with associated para-ureteral urinoma. Four cats received subcutaneous ureteral bypass (SUB) device placement and one had ureteral anastomosis over a stent. Unilateral cyst-like retroperitoneal fluid consistent with para-ureteral urinoma was observed in all cats and a diffuse retroperitoneal haematoma was noticed in four cats. No immediate major complications occurred, and all cats had post-operative serum creatinine concentration within the reference interval. The cat that had received a ureteral stent subsequently required placement of a SUB following stent encrustation 15 months after surgery. Median follow-up time was 34 (min 28, max 58) months and renal function was normal in all cats at the last follow-up.

CLINICAL RELEVANCE

Urinary diversion procedures provided long-term stable renal function following proximal TUR in these five cats. Delayed, subtle non-specific clinical signs subsequent to high-energy blunt trauma causing abdominal hernia and associated diffuse retroperitoneal haematoma, should raise suspicion of TUR.

ABBREVIATIONS

AFAST: Abdominal focused assessment with sonography for trauma; SUB: Subcutaneous ureteral bypass; TUR: Traumatic ureteral rupture.

Evaluation of Bcl-2 as a marker for chronic kidney disease prediction in cats

Chronic kidney disease (CKD) is a frequent condition in elderly cats. Bcl-2 is linked to kidney disease through the processes of apoptosis and fibrosis. The purpose of this study is to examine Bcl-2 levels in CKD and clinically healthy age-matched cats in order to evaluate the relationship between Bcl-2 levels, signalment, and blood parameters in cats with CKD. The circulating levels of Bcl-2 were determined using an immunoassay in twenty-four CKD cats and eleven clinically healthy age-matched cats by the utilization of the general linear model (GLM), Pearson correlation, principal component analysis (PCA), ROC curves, the Cox hazard model, and Kaplan-Meier survival analysis. These were all conducted in order to explore Bcl-2 levels and their connection with other variables. The Bcl-2 immunohistochemical intensity was graded in each glomerulus and tubulointerstitium. McNemar's test was performed in order to compare the expression of Bcl-2 in the two renal tissue sites. The circulating Bcl-2 of CKD cats was significantly lower than those of clinically healthy age-matched cats (P = 0.034). The presence of circulating Bcl-2 (P < 0.01) and the severity of CKD (P = 0.02) were both linked with the survival time of cats with CKD. The area under the curve (AUC) of Bcl-2 for detection of CKD was 0.723. In cats, decreased circulating Bcl-2 was associated with increased blood BUN, creatinine levels, and CKD severity. Bcl-2 protein expression was reduced in the renal tissues of CKD cats as the disease progressed, resulting in a decrease in their survival time. This study demonstrated that Bcl-2 may be effective in diagnosing feline CKD.

Body Composition of Healthy Cats and Cats with Chronic Kidney Disease Fed on a Dry Diet Low in Phosphorus with Maintenance Protein

The aim was to evaluate the effect of feeding a low-phosphorus and maintenance protein diet in healthy cats and cats with chronic kidney disease (CKD) with IRIS stages 1 (CKD-1) and 2 (CKD-2). Cats were initially fed a senior diet (30 days) followed by the renal diet (60 days). Body composition, body weight (BW), muscle mass score (MMS), and body condition score (BCS) were assessed before (T30) and after renal diet intake (T60). General mixed linear models were used to assess the effects of fixed groups and moments (T30 × T60), as well as their interaction, in addition to the random effects of animals within each group. Unlike healthy cats and cats with CKD-1, cats with CKD-2 had a loss of BW, lower BCS (p < 0.005), and lower MMS (p = 0.0008) after 60 days of consuming the renal diet. The fat mass and lean body mass (LBM), determined by the deuterium isotopes method, did not change in all cats between T0 and T60. In healthy cats and cats with CKD-1, the renal diet resulted in maintenance of BW, BCS and MMS; but cats with CKD-2 presented lower BCS and did not reduce phosphatemia after consumption.

High Intake of Sodium Chloride for 28 Days Causes No Effect on Serum FGF23 Concentrations in Cats

BACKGROUND

FGF23 is an acknowledged parameter to assess kidney health. As chronic kidney failure is one of the most common diseases in aging cats, dietary influences on renal health warrant investigation. The purpose of this study was therefore to investigate potential correlations between dietary sodium chloride and FGF23.

METHODS

In a total of two trials, 11 cats were included. In the first trial, the cats were fed a complete and balanced control diet; in the second trial, sodium chloride was added (8 g/kg/DM)). Blood, urinary, feed, and faecal samples were analysed for major minerals. FGF23 and creatinine were measured in blood and urine samples.

RESULTS

Serum phosphate and FGF23 were unaffected by high sodium chloride intake, thus showing no correlation between serum FGF23 and sodium concentrations. Apparent phosphorus digestibility was significantly increased, however, by high sodium chloride intake, whereas apparent digestibility of calcium was unaffected. The present study confirms differences in FGF23 and sodium chloride interaction in cats compared with other species. Further research regarding the correlation between sodium chloride and phosphate homeostasis is warranted.

Relationship between FGF 23, SDMA, Urea, Creatinine and Phosphate in Relation to Feline Chronic Kidney Disease

Chronic kidney disease (CKD) is a common diagnosis in older cats, and its prevalence increases with age. Conventional indirect biomarkers of glomerular filtration rate (GFR) have their limitations, and are not efficient in detecting early decreases in glomerular filtration rate. Recently, symmetric dimethylarginine (SDMA) concentrations have been proposed as a novel biomarker of GFR for the early detection of CKD. This study discusses the relationship between SDMA, FGF 23 and previously used indicators of kidney function, mainly creatinine, urea and phosphate. Ninety-nine cats were included in this study. Based on their SDMA values, 48 cats had CKD and the remaining 51 cats were used as a healthy control group. Serum of these cats was assayed for creatinine, urea and phosphate concentrations as well as FGF 23 values, and correlations between them were evaluated. Cats with CKD had higher FGF 23 concentrations than healthy cats, and no correlation was found between FGF 23 and SDMA, nor between FGF 23 and phosphate. On the other hand, phosphate strongly correlated with SDMA, urea and creatinine, making it a possible independent factor of CKD progression.

Hyperthyroidism in the Domestic Cat (Felis catus): Informed Treatment Choice Based on Survival Analysis

Hyperthyroidism is the most frequently diagnosed endocrine disorder in cats. Therapy may include pharmacological, surgical (thyroidectomy), radioactive (iodine), and dietary treatment. The choice of treatment is believed to be strongly influenced by the veterinarian’s experience, level of education, and knowledge of the current scientific literature. The history of survival rates can affect the decision for treatment by both the veterinarian and the owner. This study aimed to explore the longevity in cats diagnosed with hyperthyroidism and to identify significant variables which affect survival rates by using retrospective data from the practice. A multivariate Cox regression was applied with the following results: surgical thyroidectomy and methimazole medication produced similar longevity (median 23.5 months, P>0.05); Domestic Short Hair cats survived longer than pure breeds (median 27.2 vs 9.4 months, P<0.05); as do cats without chronic renal disease (median 28.1 vs 6.2 months, P<0.001); and those with low activities of alanine aminotransferase (median 27.1 vs 17.0 months, P<0.01). Hyperthyroidism is comorbid with renal diseases, but no cumulative effect was found on survivability. There was no difference in survival rates between surgical and pharmaceutical treatment, therefore the discussion of treatment options with owners can focus on other factors (e.g., cost, owners’ compliance, cats’ tolerance to medication, presence of comorbidities). We propose that surgery may be the preferred treatment when the survival rates are expected to be higher than one year. This would avoid high costs and potential side effects of medication.

Renal biomarkers in cats: A review of the current status in chronic kidney disease

Serum creatinine concentration, the classical biomarker of chronic kidney disease (CKD) in cats, has important limitations that decrease its value as a biomarker of early CKD. Recently, serum symmetric dimethylarginine concentration was introduced as a novel glomerular filtration rate biomarker for the early detection of CKD in cats. However, data on its specificity are still limited. The limitations of conventional biomarkers and the desire for early therapeutic intervention in cats with CKD to improve outcomes have prompted the discovery and validation of novel renal biomarkers to detect glomerular or tubular dysfunction. Changes in the serum or urinary concentrations of these biomarkers may indicate early kidney damage or predict the progression of kidney before changes in conventional biomarkers are detectable. This review summarizes current knowledge on renal biomarkers in CKD in cats, a field that has progressed substantially over the last 5 years.

Risk factors and implications associated with renal mineralization in chronic kidney disease in cats

Background

Nephrocalcinosis is a pathological feature of chronic kidney disease (CKD). Its pathophysiological implications for cats with CKD are unexplored.

Objectives

Identify nephrocalcinosis risk factors and evaluate its influence on CKD progression and all‐cause mortality.

Animals

Fifty‐one euthyroid client‐owned cats with International Renal Interest Society (IRIS) stages 2‐3 azotemic CKD.

Methods

Retrospective cohort study. Histopathological kidney sections were assessed for nephrocalcinosis (von Kossa stain). Nephrocalcinosis severity was determined by image analysis (ImageJ). Ordinal logistic regressions were performed to identify nephrocalcinosis risk factors. The influence of nephrocalcinosis on CKD progression and mortality risk were assessed using linear mixed model and Cox regression, respectively. Cats were categorized by their owner‐reported time‐averaged phosphate‐restricted diet (PRD) intake, where PRD comprised ≥50%, 10‐50%, or none of food intake.

Results

Nephrocalcinosis was rated as mild‐to‐severe in 78.4% and absent‐to‐minimal in 21.6% of cases. Higher baseline plasma total calcium concentration (tCa; odds ratio [OR] = 3.07 per 1 mg/dL; P = .02) and eating a PRD (10%‐50%: OR = 8.35; P = .01; ≥50%: OR = 5.47; P = .01) were independent nephrocalcinosis risk factors. Cats with absent‐to‐minimal nephrocalcinosis had increasing plasma creatinine (0.250 ± 0.074 mg/dL/month; P = .002), urea (5.06 ± 1.82 mg/dL/month; P = .01), and phosphate (0.233 ± 0.115 mg/dL/month; P = .05) concentrations over a 1‐year period, and had shorter median survival times than cats with mild‐to‐severe nephrocalcinosis.

Conclusion and Clinical Importance

Higher plasma tCa at CKD diagnosis and PRD intake are independently associated with nephrocalcinosis. However, nephrocalcinosis is not associated with rapid CKD progression in cats.

Subcutaneous ureteral bypass device placement in 81 cats with benign ureteral obstruction (2013-2018)

Background

Benign ureteral obstructions (BUOs) present a therapeutic challenge in cats.

Hypothesis/Objectives

The purpose of this study was to determine the outcome and complications associated with placement of subcutaneous ureteral bypass (SUB) device in cats.

Animals

Eighty‐one client‐owned cats (117 kidneys) with BUO treated by placement of a SUB.

Methods

Retrospective study. Medical records of cats with BUO and treated by SUB device placement between 2013 and 2018 were reviewed. Outcome and complications were documented.

Results

Hospital discharge rate was 94% (76/81). Serum creatinine on admission and at the time of discharge was 5.3 mg/dL (range, 1.2 to >15 mg/dL) and 2.1 mg/dL (range, 1.1‐12.5 mg/dL), respectively. Luminal obstructions were documented in 17% (18/109) of the SUB devices of 16 cats discharged from the hospital. Infection was documented in 26% (20/76) of discharged cats. Kink of the device was documented in 10% (12/117) of devices. Time to luminal obstruction and kink were 204 days (range, 21‐1678 days) and 58 days (range, 2‐601 days), respectively. Fourteen of 81 (17%) cats required a revision surgery in order to restore patency of the device. At the time of writing, 53% (43/81) of cats were alive, with a mean survival time of 821 days (range, 1‐2170 days) after surgery. Of those that died, 52% (20/38) died of urinary related causes.

Conclusion and Clinical Importance

This study suggests that SUB device placement is associated with good outcomes and could be considered for the treatment of BUO 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.

Causes of Death in Stray Cat Colonies of Milan: A Five-Year Report

Simple Summary

Cats have been closely linked to humans for thousands of years. Nowadays, stray cats are frequently hosted in colonies, protected, and enrolled in programs of trap–neuter-–return to control population increase. Italian public veterinary services work in collaboration with voluntary colony caretakers and are responsible for neutering and monitoring the health of colony cats. This retrospective study, conducted by the Anatomical Pathology Unit of the Teaching Veterinary Hospital of Milan in collaboration with the public veterinary services, was undertaken because of the limited information available regarding causes of death of colony cats. The study reports on and statistically analyzes the causes of death of colony cats in the city of Milan as assessed by necropsy. Inflammatory processes including those consistent with the most relevant feline infectious diseases were most common in kittens and young cats. Trauma was more frequent in adult cats, while organ failure was the most common cause of death in aged cats. Considering the possible animal welfare issues deriving from colony cats, awareness of the most common causes of death and collaboration between university veterinary pathologists and public veterinary services represent an essential contribution to health monitoring of colony cats and can assist in the rapid detection of possible emerging animal welfare concerns.

Abstract

The presence of cats in urban environments has a long history. In Italy, stray cats are protected by national and regional laws, and programs of neutering and reintroduction to colonies are ongoing. Colony cats have been widely studied from a behavioral perspective, while surveys regarding their causes of death are limited, although they may provide relevant information related to public health and cat welfare. This retrospective study provides pathological descriptions and statistical analyses of the causes of death of 186 cats from 100 colonies in the city of Milan. Inflammatory processes represent the primary cause of death (37.7%) and include common feline infectious diseases such as feline panleukopenia (67.5%), particularly in kittens, and feline infectious peritonitis (32.5%), most common in adult cats. Trauma was found to be a common cause of death of young/adult cats (14%) with a generally good body condition, while severe parasitosis was less represented (2.6%). The death of old cats was statistically associated with organ failure (24.7%), particularly renal failure, and tumors (11.8%). Knowledge of the most common causes of death of colony cats could make an important contribution to the health monitoring of these cats and sanitary control of their habitats and provide information on possible related emerging animal welfare concerns.

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.

Cystatin C and Neutrophil Gelatinase-Associated Lipocalin as Early Biomarkers for Chronic Kidney Disease in Dogs

Early diagnosis of chronic kidney disease (CKD) could facilitate timely and appropriate monitoring and therapy. Traditional biomarkers have limitations. Thus, new biomarkers are needed. The objective of the present study was to compare renal biomarkers (including symmetric dimethylarginine [SDMA], cystatin C [CysC], and urine neutrophil gelatinase-associated lipocalin [NGAL]-creatinine ration [UNCR]) and creatinine (CREA) for early detection of CKD in dogs. Nine healthy dogs and 32 dogs with CKD were included in this study. All dogs underwent physical examination, blood analysis (included CREA and SDMA), urinalysis, and imaging examinations. CysC and NGAL levels were measured in serum and urine, respectively. SDMA, CysC, and UNCR were significantly elevated in dogs with CKD and IRIS stage Ι (P < .0001) than in controls. CysC demonstrated a strong correlation with CREA (r² = 0.6556, P < .0001). CysC (sensitivity 93.55%, specificity 100%) had the highest sensitivity for detecting CKD, followed by UNCR (sensitivity 90%, specificity 100%), SDMA (sensitivity 84.37%, specificity 100%), and CREA (sensitivity 43.75%, specificity 100%). Additionally, CysC and UNCR (sensitivity 88.89%, specificity 100%) exhibited higher sensitivity and specificity than CREA (sensitivity 88.89%, specificity 66.67%) and SDMA (sensitivity 88.89%, specificity 88.89%) in dogs with CKD International Renal Interest Society (IRIS) stage Ι. CysC as a marker of glomerular filtration rate (GFR) and urinary NGAL as a marker of tubular damage could be used to detect CKD early in dogs better than CREA and SDMA.

Longitudinal evaluation of symmetric dimethylarginine and concordance of kidney biomarkers in cats and dogs

Symmetric dimethylarginine (SDMA) is a sensitive surrogate marker for glomerular filtration rate; however, there are uncertainties as to how to interpret mild increases (SDMA 15-19 μg/dL). This descriptive study used retrospective data to evaluate whether cats or dogs that had initial SDMA values (at T0) within the reference interval followed by an increased SDMA (at T1) had persistently increased SDMA (at T2; measured from 14 days to 18 months following T1; Persistence Cohort), and if and when cats or dogs with persistently increased SDMA had increased creatinine up to 24 months (Concordance Cohort). The Persistence Cohort included 16,670 cats and 16,712 dogs. If SDMA at T1 was 15-19 μg/dL, the probability of persistence was 53% for cats and 42% for dogs, while creatinine was concurrently increased in 20% of cats and 18% of dogs. For comparison, if SDMA was not increased at T1 the probability of increased SDMA at recheck was only 20% for cats and 9% for dogs. For cats and dogs with a T1 SDMA of 15-19 μg/dL and with persistent increases at T2, the probability of increased creatinine at T1 was 20% for cats and 18% for dogs, rising to 61% and 55%, respectively, by 24 months. When SDMA at T1 was >25 μg/dL, creatinine was increased in 93% of cats and 92% of dogs by 24 months. Mildly increased SDMA results may provide an opportunity to identify some cats and dogs earlier in their kidney disease.

Hyperammonemia in azotemic cats

OBJECTIVES

Hyperammonemia occurs in cats with hepatobiliary and nutritional (cobalamin and arginine deficiency) disorders, and has also been documented in four cats with renal azotemia. We hypothesized that in cats with renal azotemia, fasting hyperammonemia would correlate with indices of worsening kidney function, and would be independent of cobalamin, potassium, systemic inflammation or urinary tract infection (UTI) with urease-producing bacteria.

METHODS

A fasted blood sample was prospectively collected for ammonia and cobalamin analysis from 18 client-owned cats with renal azotemia (creatinine [Cr] ⩾1.6 mg/dl, urine specific gravity <1.030 or documentation of historical chronic kidney disease [CKD]). Correlations between blood ammonia and selected biochemical parameters were analyzed using Pearson's correlation coefficient.

RESULTS

Seven castrated males and 11 spayed females with a median age of 12 years (range 4-19 years) were enrolled. Ten of 18 (56%) cats presented for acute kidney injury (AKI) or acute on chronic kidney disease (AoCKD), and 8/18 (44%) presented for progressive CKD. The median Cr was 5.9 mg/dl (range 1.9-24.7 mg/dl). Hyperammonemia was documented in 4/18 (22%) cats, with a median of 95 µmol/dl (range 85-98 µmol/dl), and all four of these cats were classified as AKI/AoCKD. Blood ammonia concentrations had a significant moderate positive correlation between blood urea nitrogen (BUN) (r = 0.645, P = 0.003), Cr (r = 0.578, P = 0.012) and serum phosphorus (r = 0.714, P = 0.0009) but not with cobalamin, potassium or white blood cell count. No cats had UTIs with urease-producing bacteria.

CONCLUSIONS AND RELEVANCE

A correlation exists between blood ammonia and BUN, Cr and phosphorus in cats with renal azotemia. Future studies are warranted in a larger population of cats to determine the true prevalence, etiology and potential therapeutic effect of medical management of hyperammonemia on long-term prognosis in cats with kidney disease.

Hypoxia and chronic kidney disease: Possible mechanisms, therapeutic targets, and relevance to cats

There is mounting evidence that kidney ischaemia/hypoxia plays an important role in feline chronic kidney disease (CKD) development and progression, as well as in human disease and laboratory animal models. Ischaemic acute kidney injury is widely accepted as a cause of CKD in people and data from laboratory species has identified some of the pathways underlying this continuum. Experimental kidney ischaemia in cats results in morphological changes, namely chronic tubulointerstitial inflammation, tubulointerstitial fibrosis, and tubular atrophy, akin to those observed in naturally-occurring CKD. Multiple situations are envisaged that could result in acute or chronic episodes of kidney hypoxia in cats, while risk factors identified in epidemiological studies provide further support that kidney hypoxia contributes to spontaneously occurring feline CKD. This review evaluates the evidence for the role of kidney ischaemia/hypoxia in feline CKD and the proposed mechanisms and consequences of kidney hypoxia. As no effective treatments exist that substantially slow or prevent feline CKD progression, there is a need for novel therapeutic strategies. Targeting kidney hypoxia is one such promising approach, with therapies including those that attenuate the hypoxia-inducible factor (HIF) pathway already being utilised in human CKD.

Prevalence and type of ocular disease in a population of aged captive nondomestic felids

OBJECTIVES

Report of prevalence and type of ocular disease in a captive population of nondomestic felids.

METHODS

Medical records of 202 cats from 1993 to 2018 were reviewed. Species, age at diagnosis, sex, ocular examination abnormalities, systemic/physical examination abnormalities, type of examination (visual, sedated, or anesthetized), ocular structures affected, other diagnostics, therapy, and resolution of ocular disease were recorded.

RESULTS

A total of 202 nondomestic felids including 18 different species (bobcat, caracal, cougar, Fishing cat, Geoffroy's cat, jaguar, jungle cat, leopard, leopard cat, liger, lion, lynx, ocelot, Sand cat, Savannah cat, serval, snow leopard, and tiger) from a rescue facility were evaluated. Forty-six ocular lesions were diagnosed in 33 (16.3%) cats from 8 different species (bobcat, caracal, cougar, leopard, lion, ocelot, serval, and tiger) with a mean age of 16 ± 5.9 years at time of diagnosis. Ocular lesions included corneal disease (37%) (ulcerations, perforations, keratitis, corneal scars), cataracts (23.9%), hyphema (8.7%), lens luxation (6.5%), retinal detachment (6.5%), uveitis (4.3%), conjunctival disease (4.3%), retinal degeneration (2.1%), glaucoma (2.1%), and optic neuritis (2.1%). Therapies included medical (topical antibiotics, anti-inflammatories, serum, etc.) and/or surgical management (enucleation, intracapsular lens extraction, corneoconjunctival transposition, and corneal burr debridement).

CONCLUSIONS

To the authors' knowledge, this is the first report of the prevalence of ocular disease in a population of captive nondomestic felids. It is difficult to diagnose and treat ocular disease in nondomestic cats due to challenges related to handling, diagnostics, and therapeutics in nondomestic species. Ocular disease seen in this population is similar to that found in domestic cat populations.

Nutritional Management for Dogs and Cats with Chronic Kidney Disease

The nutritional management of canine and feline chronic kidney disease and protein-losing nephropathy is discussed. Special attention is paid to assessment of body composition (body weight, body condition score, and muscle condition score) and the dysrexia that often occurs with kidney disease. Various nutrients of concern are discussed and specific dietary options are provided.

Evaluation of mean gray values of a cat with chronic renal failure: case report

ABSTRACT In this case, a 12-year-old female domestic cat with chronic renal failure (CRF), which had lived longer than the mean survival time for cats with that condition, was monitored to evaluate the effects of treatment and mean gray value (MGV) changes. The cat has lived for nearly four years since the diagnosis. Probiotics have been used as an additional, classical supportive therapy since the beginning of treatment. The temporal changes in renal MGV were statistically evaluated in the last year of the four-year period. The cat had a comfortable existence and good body condition all her life and probiotic therapy may have had a positive influence post-CRF diagnosis. Ultrasonography (US) examination is a commonly used tool for monitoring the CRF situation, but it is not particularly sensitive. Therefore, MGV may be more useful for the quantitative evaluation of the extent of renal failure. Also, to the best of our knowledge, this is the first report for a long-term clinical evaluation of MGV in a cat with CRF. The aim of this case report was the evaluation of the relationship between MGV and clinical and biochemical changes in a cat with chronic renal failure.

Calcium, Phosphorus, and Vitamin D in Dogs and Cats: Beyond the Bones

Calcium, phosphorus, and vitamin D are nutrients that play a key role in maintaining normal organ, cell, and tissue function. Much is known about their role in bone metabolism, but these nutrients are also important in renal health, urinary tract disease, and multiple other organ systems. It is nutritionally important to meet the physiologic requirements for each of these nutrients, but the interplay between them should also be considered.

Effects of low-dose meloxicam in cats with chronic kidney disease

OBJECTIVES

Meloxicam therapy may benefit cats with degenerative joint disease, and retrospective studies suggest it could slow kidney disease progression and increase survival. This study aimed to prospectively evaluate the renal effects of low-dose meloxicam treatment (0.02 mg/kg/day) over 6 months in cats with chronic kidney disease (CKD).

METHODS

Twenty-one cats with stable International Renal Interest Society stage 2 or 3 CKD were recruited and randomized to placebo or meloxicam groups. Cats were evaluated at baseline and at 1, 3 and 6 months, including blood pressure, chemistry, symmetric dimethylarginine (SDMA), glomerular filtration rate (GFR), urinalysis, urine protein:creatinine ratio (UPC), urine transforming growth factor-beta (β):creatinine ratio, urine clusterin, urine cystatin B and serum inosine.

RESULTS

No statistical difference was observed in systolic blood pressure, blood urea nitrogen, creatinine, SDMA, GFR, urine transforming growth factor-β:creatinine ratio, urine clusterin, urine cystatin B or serum inosine in cats receiving meloxicam vs placebo. Mean UPC was greater in the meloxicam group (0.33) than the placebo group (0.1) at 6 months (P = 0.006). Four cats had meloxicam discontinued owing to potential (mainly gastrointestinal) adverse effects.

CONCLUSIONS AND RELEVANCE

No decline in renal excretory function was observed when meloxicam was administered to cats with CKD. However, gastrointestinal adverse effects were observed, and cats that received meloxicam had greater proteinuria at 6 months than cats that received placebo. As proteinuria is associated with negative outcomes (progression of azotemia and hypertension) in cats with CKD, this finding suggests that meloxicam should be used with caution in cats with CKD and UPC monitored. Until further research is available, clinicians should weigh the risk of potential increased proteinuria against quality of life benefits when considering meloxicam for analgesia in cats with renal disease.

The effect of attenuating dietary phosphate restriction on blood ionized calcium concentrations in cats with chronic kidney disease and ionized hypercalcemia

Background

Hypercalcemia is commonly observed in cats with azotemic chronic kidney disease (CKD). Dietary phosphate restriction is considered standard of care but may contribute to the development of hypercalcemia. The optimal dietary management strategy for these cats is unclear.

Objectives

To describe the effect of feeding a moderately phosphate‐restricted diet (MP; 1.5 g/Mcal phosphorus; Ca : P ratio, 1.3) to cats with concurrent azotemic CKD and ionized hypercalcemia.

Animals

Client‐owned cats with ionized hypercalcemia (ionized calcium [iCa] concentration >1.4 mmol/L) at diagnosis of CKD (n = 11; baseline hypercalcemics) or after CKD diagnosis while eating a phosphate‐restricted clinical renal diet (0.8 g/Mcal phosphorus; Ca : P ratio, 1.9; n = 10; RD hypercalcemics).

Methods

Changes in variables over time, after starting MP at visit 1, were assessed using linear mixed model analysis within each group of cats. Data are reporte as median [25th, 75th percentiles].

Results

At visit 1, iCa was 1.47 [1.42, 1.55] mmol/L for baseline hypercalcemics and 1.53 [1.5, 1.67] mmol/L for RD hypercalcemics. Blood iCa decreased (P < .001) when RD hypercalcemics were fed MP, with iCa <1.4 mmol/L in 8/10 cats after 2.2 [1.8, 3.7] months. Plasma phosphate concentrations did not change. In contrast, the baseline hypercalcemic group overall showed no change in iCa but a decrease in plasma phosphate concentration during 8.8 [5.5, 10.6] months on the MP diet, although 4/11 individual cats achieved iCa <1.4 mmol/L by 3.4 [1.0, 6.2] months.

Conclusions and Clinical Importance

Attenuation of dietary phosphate restriction could result in normalization of iCa in cats that develop hypercalcemia while eating a clinical renal diet.

Incidence and treatment of feline renal lymphoma: 27 cases

OBJECTIVES

Lymphoma is the most common feline hematopoietic malignancy. Incidence of renal lymphoma has not been reported as a subset of a large population of feline lymphoma cases. Previous studies have reported renal lymphoma as both a singular entity as well as a component of multicentric disease. The clinical presentation, diagnostic evaluation, therapy and outcomes related to renal lymphoma have not been reported since Mooney et al in 1987. This retrospective study aimed to describe the incidence of renal lymphoma, clinical signs, treatment and survival.

METHODS

Using a database of cats diagnosed with lymphoma between January 2008 and October 2017, cats with renal lymphoma were selected for further analysis. Cases were retrospectively staged according to Mooney et al (1987) and Gabor et al (1998). Data collected included age, clinical signs, clinicopathologic data, diagnostic imaging findings, lymphoma diagnostic method(s), treatment protocol(s) and survival time. Analyses comparing median survival based on therapy administered, renal lymphoma vs multicentric lymphoma, central nervous system involvement, presence of azotemia, anemia and International Renal Interest Society (IRIS) stage at diagnosis were performed.

RESULTS

From a population of 740 cats with lymphoma, 27 cats had renal lymphoma (incidence, 3.6%), and 14 of those cats had multicentric lymphoma. Fewer stage IV and V cases were identified in this data set compared with Mooney et al; however, not all cats were completely staged. Median survival (range) for cats receiving corticosteroids alone compared with those receiving an L-CHOP (L-asparaginase, vincristine, cyclophosphamide, doxorubicin, prednisolone)-based protocol was 50 days (20-1027 days) in the corticosteroid group and 203 days (44-2364 days) for the L-CHOP group (P = 0.753) for cats that died secondary to lymphoma.

CONCLUSIONS AND RELEVANCE

Neither clinical stage nor other factors were predictive of survival. Prospective studies are required to determine the optimal chemotherapy protocol.

Vitamin D Metabolism and Its Role in Mineral and Bone Disorders in Chronic Kidney Disease in Humans, Dogs and Cats

Some differences regarding Vitamin D metabolism are described in dogs and cats in comparison with humans, which may be explained by an evolutionary drive among these species. Similarly, vitamin D is one of the most important regulators of mineral metabolism in dogs and cats, as well as in humans. Mineral metabolism is intrinsically related to bone metabolism, thus disturbances in vitamin D have been implicated in the development of chronic kidney disease mineral and bone disorders (CKD-MBD) in people, in addition to dogs and cats. Vitamin D deficiency may be associated with Renal Secondary Hyperparathyroidism (RSHPT), which is the most common mineral disorder in later stages of CKD in dogs and cats. Herein, we review the peculiarities of vitamin D metabolism in these species in comparison with humans, and the role of vitamin D disturbances in the development of CKD-MBD among dogs, cats, and people. Comparative studies may offer some evidence to help further research about vitamin D metabolism and bone disorders in CKD.

The association of bacteriuria with survival and disease progression in cats with azotemic chronic kidney disease

BACKGROUND

Cats with chronic kidney disease (CKD) have an increased prevalence of positive urine cultures (PUC). Limited information is available regarding the prognosis of cats with CKD and concurrent PUC.

OBJECTIVE

To determine the association of PUC with survival time and disease progression in cats with CKD.

ANIMALS

Medical records of 509 cats diagnosed with azotemic CKD between 1997 and 2018.

METHODS

Cats were classified as having "no-PUC" or "PUC." The PUC cats were further classified as having 1 or multiple PUC, and also were classified based on the presence or absence of clinical signs of urinary tract infection (UTI). Progression of CKD was defined as a plasma creatinine concentration increase of ≥25% within 365 days of CKD diagnosis; PUC also must have occurred within this time frame. Survival time and frequency of CKD progression were compared between groups.

RESULTS

No significant difference in survival time was found between cats with no-PUC and cats with any number of PUC (P = .91), or between cats with no-PUC, 1 PUC or multiple PUC (P = .37). Also, no significant difference was found in the frequency of CKD progression between PUC and no-PUC cats (P = .5), or among no-PUC, 1 PUC and multiple PUC cats (P = .22). When assessing cats with clinical signs of lower UTI, no significant difference was found in the frequency of CKD progression between cats with true UTI, subclinical bacteriuria or no-PUC (P = .8).

CONCLUSIONS AND CLINICAL IMPORTANCE

When treated with antibiotics, PUC in cats with CKD do not affect disease progression or survival time.

Understanding the Nutritional Needs of Healthy Cats and Those with Diet-Sensitive Conditions

Diets for cats must provide complete nutrition and meet the needs of the individual patient. There is no single diet that is perfect for all cats, and veterinarians must consider the needs of the cat as well as the preferences of the owners when making dietary recommendations. This article focuses on the interface between animal factors and nutritional needs in cats and is divided into 3 sections. Section 1 addresses the dietary needs of healthy cats, including differences among life stages. Section 2 addresses common myths regarding feline nutrition. Section 3 addresses common nutrient-sensitive conditions in cats, including sarcopenia of aging.

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.

Aldosterone and the mineralocorticoid receptor in renal injury: A potential therapeutic target in feline chronic kidney disease

There is a growing body of experimental and clinical evidence supporting mineralocorticoid receptor (MR) activation as a powerful mediator of renal damage in laboratory animals and humans. Multiple pathophysiological mechanisms are proposed, with the strongest evidence supporting aldosterone-induced vasculopathy, exacerbation of oxidative stress and inflammation, and increased growth factor signalling promoting fibroblast proliferation and deranged extracellular matrix homeostasis. Further involvement of the MR is supported by extensive animal model experiments where MR antagonists (such as spironolactone and eplerenone) abrogate renal injury, including ischaemia-induced damage. Additionally, clinical trials have shown MR antagonists to be beneficial in human chronic kidney disease (CKD) in terms of reducing proteinuria and cardiovascular events, though current studies have not evaluated primary end points which allow conclusions to made about whether MR antagonists reduce mortality or slow CKD progression. Although differences between human and feline CKD exist, feline CKD shares many characteristics with human disease including tubulointerstitial fibrosis. This review evaluates the evidence for the role of the MR in renal injury and summarizes the literature concerning aldosterone in feline CKD. MR antagonists may represent a promising therapeutic strategy in feline CKD.

Persistent nonregenerative anemia in a 4-year-old cat

A 4-year-old male neutered domestic shorthair cat was presented to The Ohio State University College of Veterinary Medicine for a 2-month history of severe weight loss, lethargy, anemia, and bilaterally hyperechoic kidneys with loss of corticomedullary distinction as reported by the referring veterinarian. Relevant initial laboratory results included severe non-regenerative normocytic hypochromic anemia, increased blood urea nitrogen, minimally concentrated urine, proteinuria, and an increased urine protein:creatinine ratio. Cytologic evaluation of a bone marrow aspirate revealed a markedly hypocellular marrow with abundant mucinous material. Gelatinous marrow transformation (GMT) was confirmed histologically by the presence of mucinous material in the bone marrow that stained positive for Alcian blue but negative for periodic acid-Schiff. The cat died despite repeated blood transfusions and supportive care. Gelatinous marrow transformation, immune complex-mediated membranoproliferative glomerulonephritis, and gastrointestinal hemorrhage were observed on autopsy and histology. It is likely that the development of GMT was secondary to chronic kidney disease (CKD) and that CKD, GMT, and gastrointestinal hemorrhage contributed to the cat's non-regenerative anemia.

Predicting early risk of chronic kidney disease in cats using routine clinical laboratory tests and machine learning

Background

Advanced machine learning methods combined with large sets of health screening data provide opportunities for diagnostic value in human and veterinary medicine.

Hypothesis/Objectives

To derive a model to predict the risk of cats developing chronic kidney disease (CKD) using data from electronic health records (EHRs) collected during routine veterinary practice.

Animals

A total of 106 251 cats that attended Banfield Pet Hospitals between January 1, 1995, and December 31, 2017.

Methods

Longitudinal EHRs from Banfield Pet Hospitals were extracted and randomly split into 2 parts. The first 67% of the data were used to build a prediction model, which included feature selection and identification of the optimal neural network type and architecture. The remaining unseen EHRs were used to evaluate the model performance.

Results

The final model was a recurrent neural network (RNN) with 4 features (creatinine, blood urea nitrogen, urine specific gravity, and age). When predicting CKD near the point of diagnosis, the model displayed a sensitivity of 90.7% and a specificity of 98.9%. Model sensitivity decreased when predicting the risk of CKD with a longer horizon, having 63.0% sensitivity 1 year before diagnosis and 44.2% 2 years before diagnosis, but with specificity remaining around 99%.

Conclusions and clinical importance

The use of models based on machine learning can support veterinary decision making by improving early identification of CKD.

Chronic kidney disease in cats attending primary care practice in the UK: a VetCompassTM study

Chronic kidney disease (CKD) is a frequent diagnosis in cats attending primary care practice and the most frequent cause of death in cats aged over five years, yet there is limited published research for CKD in cats attending primary care practice. This study aimed to estimate the prevalence of CKD and investigate risk factors for diagnosis and survival of cats diagnosed with CKD in UK primary care practices. The study included cats attending VetCompass^TM practices from January 1, 2012 to December 31, 2013. A nested case-control and cohort study were undertaken. From 353,448 cats attending 244 clinics, the prevalence of CKD was estimated as 1.2 per cent (95 per cent CI 1.1 per cent to 1.3 per cent). Most cats with CKD had clinical signs at diagnosis (66.6 per cent). Few cats underwent investigations or monitoring of serum creatinine (32.6 per cent), urine protein:creatinine ratio (14.9 per cent) or blood pressure measurement (25.6 per cent). A proprietary renal diet was the most frequently prescribed management (63.8 per cent). Median survival time following diagnosis was 388 days (IQR 88-1042 days). This study provides generalisable evidence from the wider cat population to aid veterinarians in improved diagnosis and management of CKD that can benefit the health and welfare of cats with CKD in the UK.

Survival analysis to evaluate associations between periodontal disease and the risk of development of chronic azotemic kidney disease in cats evaluated at primary care veterinary hospitals

OBJECTIVE To examine potential associations between periodontal disease (PD) and the risk of development of chronic azotemic kidney disease (CKD) among cats and determine whether the risk of CKD increases with severity of PD. DESIGN Retrospective cohort study. ANIMALS 169, 242 cats. PROCEDURES Cats were evaluated ≥ 3 times at any of 829 hospitals from January 1, 2002, through June 30, 2013. Cats with an initial diagnosis of PD of any stage (n = 56,414) were frequency matched with cats that had no history or evidence of PD (112,828) by age and year of study entry. Data on signalment, PD, and other conditions potentially related to CKD were extracted from electronic medical records. Cox proportional hazards modeling was used to estimate the association of PD with CKD after controlling for covariates. RESULTS PD was associated with increased risk of CKD; risk was highest for cats with stage 3 or 4 PD. Risk of CKD increased with age. Purebred cats had greater risk of CKD than mixed-breed cats. General anesthesia within the year before study exit and diagnosis of cystitis at any point prior to study exit (including prior to study entry) were each associated with increased CKD risk. Diagnosis of diabetes mellitus or hepatic lipidosis at any point prior to study exit was associated with decreased CKD risk. CONCLUSIONS AND CLINICAL RELEVANCE The findings supported the benefit of maintaining good oral health and can be useful to veterinarians for educating owners on the importance of preventing PD in cats.

The fecal microbiome and serum concentrations of indoxyl sulfate and p-cresol sulfate in cats with chronic kidney disease

Background

Intestinal dysbiosis has been documented in humans with chronic kidney disease (CKD) and is thought to contribute to production of the uremic toxins indoxyl sulfate (IS) and p‐cresol sulfate (pCS). Characteristics of the fecal microbiome in cats with CKD and correlation to serum concentrations of uremic toxins are unknown.

Objectives

To characterize the fecal microbiome and measure serum IS and pCS concentrations of cats with CKD in comparison to healthy older cats.

Animals

Thirty client‐owned cats with CKD (International Renal Interest Society stages 2‐4) and 11 older (≥8 years) healthy control cats.

Methods

Prospective, cross‐sectional study. Fecal samples were analyzed by sequencing of 16S rRNA genes and Escherichia coli quantitative PCR (qPCR). Serum concentrations of IS and pCS measured using liquid chromatography tandem mass spectrometry.

Results

Cats with CKD had significantly decreased fecal bacterial diversity and richness. Escherichia coli qPCR showed no significant difference in bacteria count between control and CKD cats. Cats with stage 2 (P = .01) and stages 3 and 4 (P = .0006) CKD had significantly higher serum IS concentrations compared to control cats. No significant difference found between stage 2 and stages 3 and 4 CKD. The pCS concentrations were not significantly different between CKD cats and control cats.

Conclusions and Clinical Importance

Decreased fecal microbiome diversity and richness is associated with CKD in cats. Indoxyl sulfate concentration is significantly increased with CKD, and cats with stage 2 CKD may suffer from a similar uremic toxin burden as do cats with later stage disease.

Factors associated with survival in dogs with chronic kidney disease

Background: Chronic kidney disease (CKD) is associated with morbidity and mortality in dogs. Plasma fibroblast growth factor‐23 (FGF‐23) concentration is an independent predictor of CKD progression and survival in cats and people with CKD.

Objectives: To investigate the relationship among FGF‐23, parathyroid hormone (PTH), vitamin D metabolites, and other clinical variables with survival time in dogs with CKD.

Animals: Twenty‐seven azotemic CKD dogs.

Methods: Dogs were recruited prospectively into the study and followed until death or study conclusion. Dogs were International Renal Interest Society (IRIS) staged into stage 2 (n = 9), stage 3 (n = 12), and stage 4 (n = 6) CKD. Survival times were calculated from the date of study inclusion. Univariable Cox regression was used to assess variables associated with survival including body condition score (BCS), muscle condition score, hematocrit, creatinine, CKD stage, serum phosphorus, urine protein:creatinine ratio (UPC), calcium phosphorus product (CaPP), PTH, 25‐hydroxyvitamin D, 1,25‐‐dihydroxyvitamin D, and FGF‐23 concentrations.

Results: Significant hazard ratios (hazard ratio; 95% confidence interval; P value) were as follows: BCS < 4/9 (1.579; 1.003‐2.282; P = .05), muscle atrophy (2.334; 1.352‐4.030; P = .01), increased creatinine (1.383; 1.16‐1.64; .01), hyperphosphatemia (3.20; 1.357‐7.548; P = .005), increased UPC (3.191; 1.310‐7.773; P = .01), increased CaPP (4.092; 1.771‐9.454; P = .003), and increased FGF‐23 (2.609; 1.090‐6.240; P = .05). Survival times for each IRIS CKD stage were significantly different (P = .01).

Conclusions and Clinical Importance: Multiple variables, including FGF‐23, were associated with duration of survival in CKD dogs. FGF‐23 could be a prognostic marker in dogs with CKD.

Pilot study to evaluate the potential use of the renal resistive index as a preliminary diagnostic tool for chronic kidney disease in cats

Objectives Chronic kidney disease (CKD) is the most common renal pathology diagnosed in geriatric cats, and its prevalence increases with age. The arterial resistive index (RI) is important when evaluating vascular resistance and compliance, and can be applied in the kidney (renal RI [RRI]), allowing the evaluation of its vascular haemodynamics. The present study aimed to: (1) investigate in cats with CKD the relationships between the RRI and the following parameters: age, sex, body weight, plasmatic creatinine, blood urea nitrogen, potassium, urine specific gravity, urine protein:creatinine ratio and systolic arterial pressure; and (2) evaluate the potential use of the RRI as a preliminary diagnostic tool in cats with CKD. Methods The present study involved 24 cats of both sexes. Six were healthy cats (control group [CG]) and 18 had CKD, but did not have any concomitant diseases and were not being treated with any medications (study group [SG]). For RRI measurement we used colour Doppler ultrasound (CDUS). Results RRI differed significantly between the CG and SG ( P <0.01) and was higher in the SG. A statistically significant correlation was only achieved between the RRI and the body weight of the patients and it was negative. A strong and positive correlation was noted between the mean RRI of both kidneys (r = 0.66). Receiver-operating curve analysis allowed us to establish an admissible cut-off for the RRI value of 0.639 for a preliminary diagnosis of CKD for both kidneys. Conclusions and relevance No differences were found for the RRI between the left and right kidneys, suggesting that evaluation of only one kidney is sufficient to provide an estimate of the RRI value for both organs. RRI measurement, which can be achieved with CDUS, is an easy-to-use diagnostic tool that, with a cut-off value of 0.639 for both kidneys, is useful in establishing a preliminary diagnosis of CKD.

Prognostic importance of plasma total magnesium in a cohort of cats with azotemic chronic kidney disease

Background

Hypomagnesemia is associated with increased mortality and renal function decline in humans with chronic kidney disease (CKD). Magnesium is furthermore inversely associated with fibroblast growth factor 23 (FGF23), an important prognostic factor in CKD in cats. However, the prognostic significance of plasma magnesium in cats with CKD is unknown.

Objectives

To explore associations of plasma total magnesium concentration (tMg) with plasma FGF23 concentration, all‐cause mortality, and disease progression in cats with azotemic CKD.

Animals

Records of 174 client‐owned cats with IRIS stage 2‐4 CKD.

Methods

Cohort study. Cats with azotemic CKD were identified from the records of two London‐based first opinion practices (1999–2013). Possible associations of baseline plasma tMg with FGF23 concentration and risks of death and progression were explored using, respectively, linear, Cox, and logistic regression.

Results

Plasma tMg (reference interval, 1.73–2.57 mg/dL) was inversely associated with plasma FGF23 when controlling for plasma creatinine and phosphate concentrations (partial correlation coefficient, −0.50; P < .001). Hypomagnesemia was observed in 12% (20/174) of cats, and independently associated with increased risk of death (adjusted hazard ratio, 2.74; 95% confidence interval [CI], 1.35–5.55; P = .005). The unadjusted associations of hypermagnesemia (prevalence, 6%; 11/174 cats) with survival (hazard ratio, 2.88; 95% CI, 1.54–5.38; P = .001), and hypomagnesemia with progressive CKD (odds ratio, 17.7; 95% CI, 2.04–154; P = .009) lost significance in multivariable analysis.

Conclusions and Clinical Importance

Hypomagnesemia was associated with higher plasma FGF23 concentrations and increased risk of death. Measurement of plasma tMg augments prognostic information in cats with CKD, but whether these observations are associations or causations warrants further investigation.

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.

A survey of dog and cat anaesthesia in a sample of veterinary practices in New Zealand

AIMS

To survey current anaesthesia practices for dogs and cats in small and mixed animal practices in New Zealand in order to improve anaesthesia education.

METHODS

A questionnaire was sent to 440 small and mixed animal practices, including questions regarding the type of practice, preanaesthetic examination, anaesthetic drugs and management, anaesthetic machines, monitoring and topics of interest for continuing professional development.

RESULTS

Responses were obtained from 113/440 (26%) practices, with 78 (69%) respondents from small and 35 (31%) from mixed animal practices. A preanaesthetic physical examination was carried out by >95% of respondents and premedication was usually given to dogs (112/113; 99%) and cats (95/113; 85%). Acepromazine was the preferred sedative for dogs and cats, with morphine or buprenorphine. Propofol and alfaxalone were the preferred induction agents, and isoflurane was preferred for maintenance in both dogs and cats. A venous catheter was usually placed for anaesthesia in dogs (59/113; 52%), but less so in cats (39/113; 35%). Perioperative fluid was administered at 10 mL/kg/hour by 62/110 (56%) respondents. Intubation was usually used for anaesthesia in dogs (111/112; 99%), and cats (87/112; 78%). Almost 40% of respondents usually administered supplementary oxygen if patients were not intubated. Local analgesia was used by 69/111 (88%) respondents sometimes or always if applicable. Morphine or buprenorphine, and meloxicam were common choices for post-operative analgesia after neuter surgery in dogs and cats. A semiclosed (non-rebreathing) system was used in animals weighing <10 kg, and a Mapleson E or F non-rebreathing circuit was used by 66/109 (61%) practices. Only 15/111 (14%) practices had a ventilator in their practice. A dedicated anaesthetist was usually used by 104/113 (92%) practices, and apnoea alarms, pulse oximeters, thermometers and oesophageal stethoscopes were the main monitoring devices available in practices. Loco-regional block, pain management, and anaesthetic drugs were the main topics of interest for continuing education.

CONCLUSIONS AND CLINICAL RELEVANCE

Responses by the veterinarians taking part in this survey indicated that they had a reasonably good standard of anaesthetic practice. A physical examination was carried out preanaesthesia, and premedication including analgesia was routinely administered to most patients. A dedicated anaesthetist usually monitored patients and most respondents reported they had access to basic anaesthetic monitoring equipment. Areas where changes could lead to improved anaesthetic practice were increased use of I/V catheterisation, endotracheal intubation, and supplementary oxygen, and reduced I/V fluid rates.

Effects of Benazepril on Survival of Dogs with Chronic Kidney Disease: A Multicenter, Randomized, Blinded, Placebo-Controlled Clinical Trial

BACKGROUND

Chronic kidney disease (CKD) is an important cause of morbidity and mortality in dogs.

OBJECTIVE

To evaluate the efficacy in prolonging survival and safety of benazepril administration to dogs with CKD.

ANIMALS

Forty-nine client-owned dogs with CKD.

METHODS

Dogs were randomized to benazepril (0.25 to <0.5 mg/kg) or placebo once daily for up to 2 years in a prospective, multicenter, blinded clinical trial. The primary endpoint variable was the renal survival time, defined as the time from inclusion in the study to the treatment failure endpoint of death or euthanasia or need for administration of parenteral fluids related to renal failure.

RESULTS

No benefit of benazepril versus placebo was detected for renal survival time in all dogs; median (95% confidence interval (CI)) survival times were 305 (53-575) days in the benazepril group and 287 (152-not available) in the placebo group (P = .53). Renal survival times were not significantly longer with benazepril compared to placebo for subgroups: hazard ratios (95% CI) were 0.50 (0.21-1.22) with P = .12 for initial urine protein-to-creatinine ratio (UPC) >0.5, and 0.38 (0.12-1.19) with P = .080 for initial UPC >0.5 plus plasma creatinine ≤440 μmol/L. Proteinuria, assessed from the UPC, was significantly (P = .0032) lower after treatment with benazepril compared to placebo. There were no significant differences between groups for clinical signs or frequencies of adverse events.

CONCLUSIONS AND CLINICAL RELEVANCE

Benazepril significantly reduced proteinuria in dogs with CKD. Insufficient numbers of dogs were recruited to allow conclusions on survival time.