ISFM Consensus Guidelines on the Diagnosis and Management of Feline Chronic Kidney Disease

Correlation between change in serum creatinine concentration and renal cortical anisotropic backscattering artifact in azotemic cats during hospitalization

Information on the clinical outcomes of feline azotemia using ultrasound examinations is limited. This study aimed to understand the correlation between cortical anisotropy backscattering artifact (CABA) and serum creatinine (sCr) changes in feline azotemia after hospitalization and to investigate whether CABA is useful for predicting the clinical outcome of feline azotemia. Sixty-five hospitalized cats with azotemia, including 49 cats with moderate or severe azotemia (severe group) and 16 cats with mild azotemia (mild group). This retrospective study reviewed the CABA using ultrasound images of cats hospitalized with azotemia between 2016 and 2021. The correlation between CABA and the clinical outcomes of cats with azotemia was investigated using the chi-squared or Fisher's exact test, and the intra- and inter-observer agreements in CABA were assessed using McNemar's and Cohen's kappa tests. The presence of CABA was significantly positively correlated with the clinical outcomes of cats with azotemia only in the severe group (p = 0.0034, odds ratio = 8.57). There was no association between CABA and clinical outcomes in cats with mild azotemia (p = 0.75). CABA can be used for clinical outcome prediction in moderate and severe feline azotemia, with a sensitivity of 80.8% and a specificity of 73.9%. Also, satisfactory intra- and inter-observer agreements were revealed in the detection of CABA during ultrasound image review. Our study demonstrated that cats with moderate and severe azotemia with CABA observed during ultrasonography might have better clinical outcomes. These findings provide additional information on the prognosis and treatment of feline azotemia.

Diurnal variation of serum phosphorus concentrations in intact male adult domestic cats

BACKGROUND

Monitoring serum phosphorus concentrations is crucial in the management of chronic kidney disease in cats. The diurnal variation of serum phosphorus concentration may affect clinical assessment.

HYPOTHESIS/OBJECTIVES

Characterize the diurnal variation of serum phosphorus concentration in cats and determine the associations between changes in serum phosphorus concentration and several metabolites of phosphorus metabolism.

ANIMALS

Six apparently healthy, intact male, specific-pathogen-free cats were housed in a photoperiod, humidity, and temperature-controlled facility.

METHODS

Blood sampling was performed hourly for 24 hours to obtain the serum concentrations of phosphorus, ionized calcium, parathyroid hormone, and calcidiol. Results were analyzed using linear mixed-effect models to determine the significance of diurnal variation and associations between serum phosphorus concentrations and other metabolites over time.

RESULTS

Diurnal variation in serum phosphorus concentration was noted with an apex around 11:00 followed by gradually declining concentrations to reach the nadir around 23:00. The serum phosphorus concentration again increased through the early morning on the next day. An approximately 25% difference in serum phosphorus concentration at the apex and the nadir was documented. A non-linear relationship between the serum concentrations of phosphorus and ionized calcium over time was identified.

CONCLUSIONS AND CLINICAL IMPORTANCE

Diurnal variations of serum phosphorus concentration and associations between the trending of serum phosphorus and ionized calcium concentrations were evident in a group of clinically healthy adult cats housed in a controlled environment. These findings can help in the interpretation of clinical and research data regarding calcium and phosphorus metabolism and kidney health in cats.

Clinical and diagnostic evaluation of a wild ocelot (Leopardus pardalis) specimen

Background

Monitoring the health of wild animals under the principles of one health contributes to the prevention of diseases and the preservation of human and animal health, thus contributing to the conservation of species.

Aim

The current study describes the clinical and paraclinical status of an ocelot (Leopardus pardalis) captured in Buriticá, Antioquia, Colombia, for research purposes with the aim of contributing to the construction of animal health reference values in the wild, considering the scarcity of published data for the country on capture, management, and paraclinical parameters related to this species.

Methods

For this, hematological parameters, blood chemistry, urine cytochemical analyses, and coprological examinations were carried out.

Results

The hematological values of the captured individual do not show relevant differences concerning those reported in the literature in both captive and free specimens. However, differences were identified between the reference blood chemistry and urine cytochemical values between reports of animals in captivity and the wild, revealing the need to develop reference standards for animals in the wild that guarantee adequate management of these species and favor their conservation. A possible picture of renal failure and multiple parasitic infections of epidemiological importance was found.

Conclusion

This study reports for the first time a urine infection by Capillaria sp. and an infection by Dicrocoelium spp. in fecal matter for the species.

Age-related trends in urine specific gravity in apparently healthy cats

OBJECTIVES

Urine specific gravity (USG) is the most common method for the estimation of urine concentration in cats. Utilization of USG as a screening tool is easily accessible and is of low cost to the client if strategically utilized in settings of higher diagnostic value. There is currently minimal population information regarding how USG changes across ages in cats.

METHODS

Data were collected from electronic pet medical records from more than 1000 hospitals and screened for cats with an apparently healthy clinical status and complete diagnostic information. USG was compared with age in multiple analyses to examine the relationship between the variables.

RESULTS

In the absence of other indicators of disease, renal concentrating ability begins to diminish, on average, starting at approximately 9 years of age. By age group, cats aged 11-15 years (1.044, 95% confidence interval [CI] 1.043-1.044) had statistically significantly lower mean USGs compared with cats aged less than 1 year (1.049, 95% CI 1.048-1.051; P <0.001), 1-6 years (1.049, 95% CI 1.049-1.050; P <0.001) or 7-10 years (1.049, 95% CI 1.048-1.049; P <0.001). Cats aged ⩾15 years (1.038, 95% CI 1.036-1.040) had statistically significantly lower mean USGs compared with cats aged less than 1 year (P <0.001), 1-6 years (P <0.001), 7-10 years (P <0.001) or 11-15 years (P <0.001).

CONCLUSIONS AND RELEVANCE

Renal concentrating ability begins to diminish, on average, starting at approximately 9 years of age and is progressive as cat age increases. This study provides important and new information to help improve screening practices for disorders of concentrating ability in cats.

Value of repeated health screening in 259 apparently healthy mature adult and senior cats followed for 2 years

BACKGROUND

Although regular health screening is recommended, long-term follow-up data in healthy aged cats are lacking.

OBJECTIVES

Determine the most common conditions in a large group of apparently healthy older cats and which diseases are manifested within 2 years in cats confirmed to be healthy based on extensive health screening.

ANIMALS

Client-owned cats.

METHODS

Prospective study. Thorough history, physical examination, blood tests, and urinalysis were performed in 259 apparently healthy mature adult (7-10 years) and senior (>10 years) cats. Semi-annual follow-up examinations were performed in 201 confirmed healthy cats.

RESULTS

At baseline, 21% of apparently healthy cats were not considered healthy but were diagnosed with International Renal Interest Society (IRIS) ≥ stage 2 chronic kidney disease (CKD; 7.7%) or hyperthyroidism (4.6%), among other disorders. Disease occurred significantly more frequently in senior cats compared with mature adult cats. In addition, 40% cats were overweight, 35% had moderate to severe dental disease, and 22% had abnormal cardiac auscultation findings. Within 2 years, 28% of mature adult and 54% of senior cats that were confirmed healthy at inclusion developed new diseases, most commonly IRIS ≥ stage 2 CKD (cumulative incidence, 13.4%), hyperthyroidism (8.5%), chronic enteropathy, hepatopathy or pancreatitis (7.5%), or neoplasia (7%).

CONCLUSIONS AND CLINICAL IMPORTANCE

The high prevalence and 2-year incidence of physical examination abnormalities and systemic diseases in apparently healthy older cats argue for regular health screening in cats ≥7 years of age. Although more common in senior cats, occult disease also occurs in mature adult cats, and owners should be informed accordingly.

Optimization and validation of metabolomics methods for feline urine and serum towards application in veterinary medicine

BACKGROUND

Metabolomics is an emerging and powerful technology that offers a comprehensive view of an organism's physiological status. Although widely applied in human medicine, it is only recently making its introduction in veterinary medicine. As a result, validated metabolomics protocols in feline medicine are lacking at the moment. Since biological interpretation of metabolomics data can be misled by the extraction method used, species and matrix-specific optimized and validated metabolomic protocols are sorely needed.

RESULTS

Systematic optimization was performed using fractional factorial experiments for both serum (n = 57) and urine (n = 24), evaluating dilution for both matrices, and aliquot and solvent volume, protein precipitation time and temperature for serum. For the targeted (n = 76) and untargeted (n = 1949) validation of serum respectively, excellent instrumental, intra-assay and inter-day precision were observed (CV ≤ 15% or 30%, respectively). Linearity deemed sufficient both targeted and untargeted (R2 ≥ 0.99 or 0.90, respectively). An appropriate targeted recovery between 70 and 130% was achieved. For the targeted (n = 69) and untargeted (n = 2348) validation of the urinary protocol, excellent instrumental and intra-assay precision were obtained (CV ≤ 15% or 30%, respectively). Subsequently, the discriminative ability of our metabolomics methods was confirmed for feline chronic kidney disease (CKD) by univariate statistics (n = 41 significant metabolites for serum, and n = 55 for urine, p-value<0.05) and validated OPLS-DA models (R2(Y) > 0.95, Q2(Y) > 0.65, p-value<0.001 for both matrices).

SIGNIFICANCE

This study is the first to present an optimized and validated wholistic metabolomics methods for feline serum and urine using ultra-high performance liquid chromatography coupled to quadrupole-Orbitrap high-resolution mass spectrometry. This robust methodology opens avenues for biomarker panel selection and a deeper understanding of feline CKD pathophysiology and other feline applications.

Establishing a Reference Interval for Fibroblast Growth Factor (FGF)-23 in Cats

Fibroblast growth factor (FGF)-23 is a phosphaturic hormone. An association between increasing FGF-23 levels and progression of chronic kidney disease (CKD) was documented in cats, dogs, and humans. The information regarding reference intervals (RIs) of FGF-23 in cats is limited. We aimed to establish RIs in a large cohort of clinically healthy cats and to investigate correlations with sex and age. A total of 118 cats with unremarkable complete blood count and serum chemistry profile were included. Clinically sick cats, cats with concurrent diseases, suspicion of CKD, or receiving renal diets were excluded. FGF-23 concentrations were measured with the FGF-23 ELISA Kit. RIs were calculated using the reference interval advisor software 2.1 (Microsoft Excel). FGF-23 concentrations were correlated with sex and age. The RI for FGF-23 concentrations spanned 85.8 to 387.0 pg/mL (90% confidence interval: lower limit 40.5 to 103.9 pg/mL, upper limit: 354.6 to 425.0 pg/mL). No significant relationships (r2 = 0.044) were detected with age (p = 0.081) or sex (p = 0.191). Other studies of the same diagnostic assay calculated RIs of 56 to 700 pg/mL in 79 cats and <336 pg/mL in 108 cats, and in concordance with the present study, did not detect any correlation with sex or age.

Exploring the relationship between calcitonin, ionized calcium, and bone turnover in cats with and without naturally occurring hypercalcemia

Objectives

This case-control study aimed to evaluate calcitonin response in naturally occurring hypercalcemia in cats and assess the relationships between calcitonin and ionized calcium (iCa) and examine relationships between calcitonin, iCa and bone turnover.

Methods

Hypercalcemic cats (persistently increased iCa concentration [>1.40 mmol/l]) were identified retrospectively via a medical database search; additional hypercalcemic and normocalcemic cats were recruited prospectively. Data regarding routine biochemical and urine testing, diagnostic imaging and additional blood testing were obtained. Serum alkaline phosphatase (ALP) activity was used as a marker of bone turnover. Serum calcitonin concentration was analyzed using a previously validated immunoradiometric assay. Hypercalcemic cats with an increased calcitonin concentration (>0.9 ng/L) were termed responders. Group comparisons were performed using a Mann-Whitney test for continuous variables and a χ2 test for categorical variables. Spearman's correlation coefficient was used to examine the relationships between calcitonin, iCa and ALP.

Results

Twenty-six hypercalcemic and 25 normocalcemic cats were recruited. Only 5/26 (19.2%) of the hypercalcemic cats were identified as responders, and all were diagnosed with idiopathic hypercalcemia. There was no significant correlation between the concentrations of calcitonin and iCa (p = 0.929), calcitonin and ALP (p = 0.917) or iCa and ALP (p = 0.678) in hypercalcemic cats, however, a significant negative correlation was observed between calcitonin and ALP (p = 0.037) when normocalcemic and hypercalcemic cats with an elevated calcitonin concentration were analyzed together.

Discussion

The expected increase in calcitonin concentration was present in only a small subset of hypercalcemic cats; no correlation was found between iCa and calcitonin concentration. The inverse relationship between calcitonin and ALP in cats with increased calcitonin concentrations suggests that the ability of calcitonin to correct hypercalcemia may be related to the degree of bone turnover.

Urinary angiotensin-converting enzyme 2 and its activity in cats with chronic kidney disease

Introduction

Angiotensin-converting enzyme 2 (ACE2) played an important role in the renin-angiotensin-aldosterone system (RAAS) and it was proved to be renoprotective in renal disease. Urinary angiotensin-converting enzyme 2 (uACE2) has been shown to reflect renal injury in human and experimental studies, but its role in feline kidney disease remains unknown.

Aims

Our objectives involve comparing uACE2 concentrations and activities in cats across CKD stages with healthy controls, investigating the relationship between uACE2 concentrations, activities, and clinicopathological data in feline CKD patients, and assessing the predictive abilities of both for CKD progression.

Methods

A retrospective, case-control study. The concentration and activity of uACE2 were measured by commercial ELISA and fluorometric assay kits, respectively. The concentration was adjusted to give uACE2 concentration-to-creatinine ratios (UACCRs).

Results

In total, 67 cats consisting of 24 control and 43 chronic kidney disease (CKD), including 24 early-stage CKD and 19 late-stage CKD, were enrolled in this study. UACCR values were significantly higher in both early-stage (2.100 [1.142-4.242] x 10-6) and late-stage feline CKD (4.343 [2.992-5.0.71] x 10-6) compared to healthy controls (0.894 [0.610-1.076] x 10-6; p < 0.001), and there was also significant difference between-early stage group and late-stage group (p = 0.026). Urinary ACE2 activity (UAA) was significantly lower in CKD cats (1.338 [0.644-2.755] x pmol/min/ml) compared to the healthy cats (7.989 [3.711-15.903] x pmol/min/ml; p < 0.001). UACCR demonstrated an independent, positive correlation with BUN (p < 0.001), and UAA exhibited an independent, negative correlation with plasma creatinine (p < 0.001). Both UACCR and UAA did not yield significant results in predicting CKD progression based on the ROC curve analysis.

Conclusion and clinical importance

uACE2 concentration and activity exhibit varying changes as renal function declines, particularly in advanced CKD cats.

Determination of the reference interval for urine kidney injury molecule-1 in 50 healthy cats

OBJECTIVES

The aim of the present study was to establish a reference interval (RI) for urine kidney injury molecule-1 (KIM-1) in healthy cats.

METHODS

History, physical examination, blood pressure, and feline immunodeficiency virus and feline leukemia virus serology status were determined. A complete blood cell count, serum biochemical profile, urinalysis and kidney ultrasound were performed, and N-terminal pro-brain natriuretic peptide, total thyroxine (TT4) and urine KIM-1 were measured. An RI was calculated and the effect of age, sex, body condition score (BCS), blood pressure, symmetric dimethylarginine (SDMA), serum creatinine concentration (SCr), phosphorus, TT4, urine specific gravity (USG) and mid-sagittal kidney length on urine KIM-1 was evaluated using a general linear model.

RESULTS

Of 69 recruited cats, 50 met the inclusion criteria. There were 35 male cats and 15 female cats, with a median age of 4.3 years (range 1.0-12.3), median weight of 5.11 kg (range 2.52-8.45) and median BCS of 6/9 (range 3-8). The median serum concentrations were SDMA 11.0 µg/dl (range 2-14), SCr 88.5 µmol/l (range 47-136), phosphorus 1.41 mmol/l (range 0.8-2.2) and TT4 32.0 nmol/l (range 17-51). Median USG was 1.057 (range 1.035-1.076), mid-sagittal left kidney length was 3.50 cm (range 2.94-4.45) and mid-sagittal right kidney length was 3.70 cm (range 3.06-4.55). The derived RI for urine KIM-1 was 0.02-0.68. USG was a significant (P <0.001) predictor of urine KIM-1. Individually, age, sex, blood pressure, BCS, SDMA, SCr, phosphorus, TT4 and mid-sagittal kidney length were not significant predictors of urine KIM-1. In a multivariate model, if combined with USG, SDMA concentration was predictive (P = 0.030) of urine KIM-1.

CONCLUSIONS AND RELEVANCE

Urine concentration was significantly correlated with urine KIM-1, which will be an important consideration when interpreting findings in cats with potential kidney injury.

Effects of Beraprost with or without NOS Inhibition on Plasma Aldosterone and Hemodynamics in Healthy Cats

OBJECTIVES

The aim of the study was to evaluate the hemodynamic and RA system effects of the oral administration of the clinical dose of beraprost for feline CKD in healthy cats, and also to examine whether NOS inhibition reversed them.

METHODS

A placebo-controlled pharmacological sequential design study was carried out to assess the plasma aldosterone and renin concentrations (PAC and PRC), blood pressure, heart rate, and exploratorily to estimate renal plasma flow (RPF) and renal vascular resistance (RVR) with simplified methods.

RESULTS

Beraprost reduced PAC when compared to the placebo (p < 0.05); this was reversed when NOS inhibitor NG-nitro-L-arginine methyl ester (L-NAME) was added to the beraprost treatment (p < 0.01). No differences in the PRC or hemodynamic parameters were detected between beraprost and the placebo. The correlation ratios (η2) showed opposite relationships between beraprost and the added L-NAME effects on PAC, mean blood pressure (MBP), heart rate, estimated RPF (p < 0.001), estimated RVR (p < 0.01), and PRC (p < 0.05).

CONCLUSIONS

In healthy cats, the clinical dose of beraprost suppresses PAC, which can be reversed by the inhibition of NOS.

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.

Urine concentrating ability in cats with hyperthyroidism: Influence of radioiodine treatment, masked azotemia, and iatrogenic hypothyroidism

BACKGROUND

Hyperthyroid cats often have urine specific gravity (USG) values <1.035. It remains unclear how USG changes after treatment, if USG can be used to predict azotemia after treatment, or how iatrogenic hypothyroidism influences USG values.

OBJECTIVES

To determine the proportion of hyperthyroid cats with USG <1.035 vs ≥1.035; if USG changes after treatment; and whether USG <1.035 correlated with unmasking of azotemia or hypothyroidism.

ANIMALS

Six hundred fifty-five hyperthyroid cats treated with radioiodine; 190 clinically normal cats.

METHODS

Prospective, before-and-after study. Hyperthyroid cats had serum thyroxine, thyroid-stimulating hormone, and creatinine concentrations, and USG measured before and 6 months after successful treatment with radioiodine.

RESULTS

Of untreated hyperthyroid cats, USG was ≥1.035 in 346 (52.8%) and <1.035 in 309 (47.2%). After treatment, 279/346 (80.6%) maintained USG ≥1.035, whereas 67/346 (19.4%) became <1.035; 272/309 (88%) maintained USG <1.035, whereas 37/309 (12%) became ≥1.035. Only 22/346 (6.4%) with USG ≥1.035 developed azotemia after treatment, compared with 136/309 (44%) with <1.035 (P < .001). Of cats remaining nonazotemic, 38% had USG <1.035, compared with 20% of normal cats (P < .001). The 137 cats with iatrogenic hypothyroidism had lower USG after treatment than did 508 euthyroid cats (1.024 vs 1.035), but USGs did not change after levothyroxine supplementation. USG <1.035 had high sensitivity (86.1%) but moderate specificity (65.2%) in predicting azotemia after treatment.

CONCLUSIONS AND CLINICAL IMPORTANCE

Hyperthyroidism appears not to affect USG in cats. However, cats with evidence of sub-optimal concentrating ability before radioiodine treatment (USG < 1.035) are more likely to develop azotemia and unmask previously occult chronic kidney disease. Iatrogenic hypothyroidism itself did not appear to affect USG values.

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.

Case report: A novel occurrence of persistent left cranial vena cava coexisting with polycystic kidney disease in a cat

A 7-year-old castrated male Munchkin cat was presented with anorexia. This cat had been diagnosed with chronic kidney disease due to polycystic kidney disease. Tachycardia with a systolic murmur (grade III/VI) was auscultated and for further diagnosis, echocardiography was performed. Based on echocardiography, persistent left cranial vena cava (PLCVC) was suspected due to enlargement of the coronary sinus and confirmed by saline contrast echocardiography. The dilated coronary sinus compressed the left atrium, and left ventricular hypertrophy with the systolic anterior motion of the mitral valve, aortic regurgitation, and mitral regurgitation were identified. After medical management using atenolol, left atrial function and other hemodynamics of the heart were improved, including the disappearance of regurgitation and normalization of left ventricular wall thickness. This case report describes the echocardiographic characteristics, diagnostic procedures, and disease progression in a cat with PLCVC after medical management using atenolol. Additionally, this is the first report of a cat with PLCVC, coexisting with polycystic kidney disease.

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.

Large-scale epidemiological study on feline autosomal dominant polycystic kidney disease and identification of novel PKD1 gene variants

OBJECTIVES

Autosomal dominant polycystic kidney disease (ADPKD) is a common inherited disease in cats. In most cases, the responsible abnormality is a nonsense single nucleotide polymorphism in exon 29 of the PKD1 gene (chrE3:g.42858112C>A, the conventional PKD1 variant). The aim of this study was to conduct a large-scale epidemiological study of ADPKD caused by the conventional PKD1 variant in Japan and to search for novel polymorphisms by targeted resequencing of the PKD1 using a next-generation sequencer.

METHODS

A total of 1281 cats visiting the Veterinary Medical Center of the University of Tokyo were included in this study. DNA was extracted from the blood of each cat. We established a novel TaqMan real-time PCR genotyping assay for the conventional PKD1 variant, and all cases were examined for the presence of this variant. Targeted resequencing of all exons of the PKD1 was performed on the DNA of 23 cats with the conventional PKD1 variant, six cats diagnosed with cystic kidneys but without this variant, and 61 wild-type normal cats.

RESULTS

Among the 1281 cats examined in this study, 23 (1.8%) harboured the conventional PKD1 variant. The odds of having the conventional PKD1 variant were significantly higher in Persian cats, Scottish Folds and Exotic Shorthairs than in the other breeds, although the number of cases in each breed was small. Furthermore, we identified four variants unique to cats with cystic kidneys that were not found in wild-type normal cats, all of which were in exon 15. In particular, two (chrE:g.42848725delC, pGly1641fs and chrE:g.42850283C>T, pArg2162Trp) were candidate variants.

CONCLUSIONS AND RELEVANCE

This study revealed that the conventional PKD1 variant was prevalent in Scottish Fold, Persian and Exotic Shorthair breeds in Japan, and variants in exon 15 of PKD1, in addition to the conventional variant in exon 29, would be key factors in the pathogenesis of ADPKD in cats.

Comparison of Three Different Diagnostic Assays for Fibroblast Growth Factor-23 (FGF-23) Measurements in Cats: A Pilot Study

Fibroblast growth factor-23 (FGF-23) is a phosphaturic hormone used to monitor chronic kidney disease (CKD) in humans. The aim of this pilot study was to compare three diagnostic assays and to assess how the results correlate with parameters of renal dysfunction in cats. Four groups of 10 cats each were formed retrospectively according to creatinine, based on IRIS staging. FGF-23 was measured using two different ELISAs (MyBioSource and Kainos ELISA FGF-23 Kit) and an automated assay on the DiaSorin Liaison platform. Measurements were performed in 40 cats. Spearman's rank correlation coefficient showed a strong correlation between the Kainos and DiaSorin assays (ρ = 0.742/p < 0.001) and a low correlation (ρ = 0.443/p = 0.005) between the Kainos and MyBioSource assays. The measurements with the Kainos assay strongly correlated with urea (ρ = 0.835/p < 0.001) and creatinine (ρ = 0.764/p < 0.001), and moderately correlated with SDMA (ρ = 0.580/p < 0.001) and phosphorus (ρ = 0.532/p < 0.001). The results of the MyBioSource and DiaSorin assays only showed a moderate correlation with urea (ρ = 0.624/0.572) and creatinine (ρ = 0.622/0.510) concentrations (p = 0.001 each). The Kainos assay showed the strongest correlation (ρ = 0.806) with the various creatinine concentrations according to the IRIS, followed by the MyBioSource (ρ = 0.663/p < 0.001) and DiaSorin assays (ρ = 0.580/p < 0.001). Overall, the Kainos assay demonstrated the best correlations with both biomarkers and various creatinine concentrations according to the IRIS. Individual assay-based reference values should be established to make a reliable interpretation of FGF-23 levels possible to diagnose or monitor feline CKD.

MORBIDITY AND MORTALITY OF BINTURONGS (ARCTICTIS BINTURONG) IN UNITED STATES ZOOLOGICAL INSTITUTIONS (1986-2019)

Veterinary literature on diseases in binturong (Arctictis binturong) is often limited to case series or reports without population-level information. Morbidity and mortality data were collected from North American institutions through survey completion or submission of medical records. Responses included information about 74 individuals (37 males, 30 females, and 7 unknown neonates) representing 22 institutions, from 1986 to 2019. Antemortem data were available from 39 individuals, and postmortem data were available from 53 individuals. Eighteen individuals had both antemortem and postmortem records available. Age (mean ± SD) at death for adults (n = 41) was 15.2 ± 4.3 yr. Morbidity events were summarized by affected organ system; 160 events were reported. The systems with the most frequently reported events were gastrointestinal (33%; 53/160), integumentary (19%; 31/160), urinary (12%; 20/160), and musculoskeletal (19 [12%] of 160). Excluding neonates, primary causes of mortality included neoplasia (51%; 21/41), infectious or inflammatory diseases (24%; 10/41), and cardiovascular disease (17%; 7/41). Neoplasms (51%; 21/41) confirmed on histopathology included renal adenocarcinoma (47%; 10/21); mammary carcinoma (14%; 3/21); pancreatic islet cell carcinoma (2 [10%] of 21); and single instances of multicentric lymphoma, uterine carcinoma, and submucosal urethral adenoma. There were three additional cases of presumed neoplasia without histopathologic confirmation; masses were detected in the liver, heart base, and pancreas. Metastases were reported in 15 (71%) of 21 neoplasms. Although neoplasia and cardiovascular disease were common causes of mortality, they were rarely diagnosed antemortem. Neoplasia was often malignant and generally diagnosed after metastasis. Preventive medicine protocols with improved renal and cardiovascular evaluation are warranted and may result in earlier detection of subclinical disease in binturong.

Assessment of peritubular capillary rarefaction in kidneys of cats with chronic kidney disease

BACKGROUND

Hypoxia is a key driver of fibrosis and is associated with capillary rarefaction in humans.

OBJECTIVES

Characterize capillary rarefaction in cats with chronic kidney disease (CKD).

ANIMALS

Archival kidney tissue from 58 cats with CKD, 20 unaffected cats.

METHODS

Cross-sectional study of paraffin-embedded kidney tissue utilizing CD31 immunohistochemistry to highlight vascular structures. Consecutive high-power fields from the cortex (10) and corticomedullary junction (5) were digitally photographed. An observer counted and colored the capillary area. Image analysis was used to determine the capillary number, average capillary size, and average percent capillary area in the cortex and corticomedullary junction. Histologic scoring was performed by a pathologist masked to clinical data.

RESULTS

Percent capillary area (cortex) was significantly lower in CKD (median 3.2, range, 0.8-5.6) compared to unaffected cats (4.4, 1.8-7.0; P = <.001) and was negatively correlated with serum creatinine concentrations (r = -.36, P = .0013), glomerulosclerosis (r = -0.39, P = <.001), inflammation (r = -.30, P = .009), and fibrosis (r = -.30, P = .007). Capillary size (cortex) was significantly lower in CKD cats (2591 pixels, 1184-7289) compared to unaffected cats (4523 pixels, 1801-7618; P = <.001) and was negatively correlated with serum creatinine concentrations (r = -.40, P = <.001), glomerulosclerosis (r = -.44, P < .001), inflammation (r = -.42, P = <.001), and fibrosis (r = -.38, P = <.001).

CONCLUSIONS AND CLINICAL IMPORTANCE

Capillary rarefaction (decrease in capillary size and percent capillary area) is present in kidneys of cats with CKD and is positively correlated with renal dysfunction and histopathologic lesions.

Life expectancy tables for dogs and cats derived from clinical data

There are few recent and methodologically robust life expectancy (LE) tables for dogs or cats. This study aimed to generate LE tables for these species with clinical records from >1,000 Banfield Pet hospitals in the USA. Using Sullivan's method, LE tables were generated across survey years 2013-2019, by survey year, and for subpopulations defined by sex, adult body size group (purebred dogs only: toy, small, medium, large and giant), and median body condition score (BCS) over life. The deceased population for each survey year comprised animals with a recorded date of death in that year; survivors had no death date in that year and were confirmed living by a veterinary visit in a subsequent year. The dataset totaled 13,292,929 unique dogs and 2,390,078 unique cats. LE at birth (LE_birth) was 12.69 years (95% CI: 12.68-12.70) for all dogs, 12.71 years (12.67-12.76) for mixed-breed dogs, 11.18 years (11.16-11.20) for cats, and 11.12 (11.09-11.14) for mixed-breed cats. LE_birth increased with decreasing dog size group and increasing survey year 2013 to 2018 for all dog size groups and cats. Female dogs and cats had significantly higher LE_birth than males: 12.76 years (12.75-12.77) vs. 12.63 years (12.62-12.64), and 11.68 years (11.65-11.71) vs. 10.72 years (10.68-10.75), respectively. Obese dogs (BCS 5/5) had a significantly lower LE_birth [11.71 years (11.66-11.77)] than overweight dogs (BCS 4/5) [13.14 years (13.12-13.16)] and dogs with ideal BCS 3/5 [13.18 years (13.16-13.19)]. The LE_birth of cats with BCS 4/5 [13.67 years (13.62-13.71)] was significantly higher than cats with BCS 5/5 [12.56 years (12.45-12.66)] or BCS 3/5 [12.18 years (12.14-12.21)]. These LE tables provide valuable information for veterinarians and pet owners and a foundation for research hypotheses, as well as being a stepping-stone to disease-associated LE tables.

Comparison of ultrasonographic renal measurements in kittens up to 3 months of age and young cats

OBJECTIVES

This study aimed to evaluate renal measurements by B-mode ultrasound in kittens during their first 3 months and compare them with those of young adult cats.

METHODS

Forty-eight healthy mixed-breed cats (24 males and 24 females) were enrolled in this study. The cats were divided into six age groups: groups 1-5 (kittens) and group 6 (young adult cats). Each kidney was examined using B-mode imaging and the following measurements taken: renal length (RL), renal height (RH), renal width (RW), cortical thickness (CoT), medullary thickness (MdT) and corticomedullary ratio (CMr). The ratio and correlation of RL to aortic diameter (AoD) and the length of the fifth/sixth lumbar vertebrae (LLV) were also determined.

RESULTS

Among groups, there was a statistically significant difference between RW, renal volume (RV), CoT, MdT and CMr. The smallest renal dimensions were obtained in the youngest kittens (up to 10 days of age), including RL (1.84 ± 0.40 cm), RH (1.14 ± 0.17 cm), RW (1.25 ± 0.20 cm) and RV (1.47 ± 0.68 ml). A strong correlation was observed between RL:AoD and RL:LLV, allowing for linear regression equations and reference intervals for RL:AoD and RL:LLV to be created for each age group.

CONCLUSIONS AND RELEVANCE

B-mode ultrasound showed that renal measurements in kittens differed from those in young adult cats, and that the renal dimensions, renal CoT and CMr increased with the growth of the cat. The RL-LLV ratio is a reliable method for measuring RL according to age group.

An early prediction model for canine chronic kidney disease based on routine clinical laboratory tests

The aim of this study was to derive a model to predict the risk of dogs developing chronic kidney disease (CKD) using data from electronic health records (EHR) collected during routine veterinary practice. Data from 57,402 dogs were included in the study. Two thirds of the EHRs were used to build the model, which included feature selection and identification of the optimal neural network type and architecture. The remaining unseen EHRs were used to evaluate model performance. The final model was a recurrent neural network with 6 features (creatinine, blood urea nitrogen, urine specific gravity, urine protein, weight, age). Identifying CKD at the time of diagnosis, the model displayed a sensitivity of 91.4% and a specificity of 97.2%. When predicting future risk of CKD, model sensitivity was 68.8% at 1 year, and 44.8% 2 years before diagnosis. Positive predictive value (PPV) varied between 15 and 23% and was influenced by the age of the patient, while the negative predictive value remained above 99% under all tested conditions. While the modest PPV limits its use as a stand-alone diagnostic screening tool, high specificity and NPV make the model particularly effective at identifying patients that will not go on to develop CKD.

In Vitro Growth, Receptor Usage and Pathogenesis of Feline Morbillivirus in the Natural Host

Feline morbillivirus (FeMV) is a recently discovered virus belonging to the genus Morbillivirus of the virus family Paramyxoviridae. Often, the virus has been detected in urine of cats with a history of urinary disease and has a worldwide distribution. Currently, it is unclear which receptor the virus uses to enter the target cells. Furthermore, many aspects of FeMV biology in vivo, including tissue tropism, pathogenesis, and virus excretion in the natural host remain unclear. In this study we analyzed the replication of FeMV in various cell lines. Secondly, we tested if the presence of feline SLAMF1 (Signaling Lymphocytic Activation Molecule family 1/CD150, principal entry receptor for other members of the Morbillivirus genus) improved FeMV replication efficiency in vitro. Finally, to elucidate in vivo biology in cats, as a natural host for FeMV, we experimentally infected a group of cats and monitored clinical symptoms, viremia, and excretion of the virus during the course of 56 days. Our study showed that FeMV shares some features with other morbilliviruses like the use of the SLAMF1 receptor. For the first time, experimental infection of SPF cats showed that FeMV does not induce an acute clinical disease like other morbilliviruses but can induce lesions in the kidneys, including tubulointerstitial nephritis. Further investigations are needed to confirm the site and dynamics of replication of FeMV in the urinary tract and the longer-term impact of FeMV-induced lesions on the renal function. Whether FeMV infection can result in chronic kidney disease will require the monitoring of cats over a longer period.

Urinary Protein/Creatinine Ratio in Feline Medicine: Reasons to Perform It and Its Role in Clinical Practice-A Retrospective Study

This study aimed at understanding the reasons veterinarians conduct a urinary protein/creatinine ratio (UPCR) in cats, correlating it with signalment, dipstick proteinuria tests, and urine specific gravity (USG) and assessing its role in chronic kidney disease (CKD) diagnosis and monitoring. A retrospective study was conducted, including medical data from cats consulted between 2016 and 2018 in a veterinary teaching hospital and submitted to at least one UPCR measurement. A total of 140 cats were included: 35% non-proteinuric (UPCR < 0.2), 25% borderline proteinuric (0.2 < UPCR < 0.4), and 40% overtly proteinuric (UPCR > 0.4). In contrast to other studies, there was no association between UPCR and male reproductive status. UPCR was mainly requested for CKD diagnosis and monitoring. Correlation between UPCR and combined results from dipstick tests and USG was low and inconsistent. Proteinuric CKD cats had a worse outcome at both 6 (odds ratio (OR 4.04) and 12 months (OR 4.36)), and this finding was more pronounced for severely proteinuric cases in which the OR for death was 4.36 and 6.00 at 6 and at 12 months, respectively. In addition to reinforcing the negative prognostic value of proteinuria, this study stresses the low and the inconsistent agreement between UPCR and the combined results of dipstick tests and USG in cats.

Aging in Cats: Owner Observations and Clinical Finding in 206 Mature Cats at Enrolment to the Cat Prospective Aging and Welfare Study

Two hundred and six cats, aged between 7 and 10 years, from the North-west of the UK, were enrolled in a cat aging and welfare study to determine the frequency of age-related conditions and associations with husbandry, owner observations of physical appearance, activity and behavior. This is the largest study to date of mature cats that includes data from an owner questionnaire and clinical examinations. At enrolment, owners frequently reported physical changes (53%), behavioral changes (47%), changes to eating patterns (41%), and activity changes (40%) in their mature cats. On physical examination, 45% cats were in overweight condition and 12% were obese. A heart murmur was detected in 29% cats, whilst indirect systolic blood pressure (SBP) was >160 mmHg in 5% cats. Dental disease was present in 54% cats and was associated with a matted hair coat (P = 0.01), increased sleeping (P = 0.02), absence of gray hairs (P = 0.03), and increased irritability to other pets (P = 0.04). Abnormalities were evident in 58% of cats that allowed an orthopedic examination (OE) to be performed. These cats were older than cats with a normal OE (P = 0.01), and abnormal OE findings were associated with a matted coat (P = 0.03) and increased grooming (P = 0.04). Aazotaemia was present in 10% cats, and this was associated with cats being observed to “sniff their food and then walk away” (P = 0.04). Hyperthyroidism was diagnosed in 3% cats, who were older (P = 0.02), had a leaner BCS (P = 0.02) and lesser blood creatinine concentrations (P = 0.01). Hyperthyroid cats were also more likely to have increased liver enzyme activity and increased SBP (P = <0.001) compared with non-hyperthyroid cats. Of the 176 cats where all clinical assessments were conducted, only 12% had no evidence of any disease. Clinical abnormalities are commonly identified when thorough, clinical assessments are performed in mature pet cats visiting primary care practice.

A saliva urea test strip for use in feline and canine patients: a pilot study

We evaluated a saliva urea test strip (Kidney-Chek; SN Biomedical), as a rapid, noninvasive method to screen for azotemia. The test is a semiquantitative method that assesses 7 levels of saliva urea concentration, and indirectly serum urea, from <3 to >17 mmol/L. Ninety-two dogs (14 azotemic) with serum urea of 1.3–37 mmol/L and 56 cats (16 azotemic) with serum urea of 4.1–89.3 mmol/L were enrolled. A positive correlation was found for saliva urea against serum urea in each species (dogs: r_s = 0.30, p < 0.005; cats: r_s = 0.50, p < 0.001). After turning the semiquantitative data into continuous data by attributing to each level the midpoint of the described range, a receiver operating characteristic curve analysis showed good performance for detecting serum urea above the upper limit of the laboratory RI (dogs: 2.1–11.1 mmol/L; cats: 5–12.9 mmol/L), with an area under the curve of 0.81 in dogs and 0.83 in cats. We recommend that the test be used as an exclusion test, given that it cannot confidently confirm azotemia with higher test results. Additional investigations are recommended for dogs with a test strip reading of ≥9–11 mmol/L and for cats with a test strip reading of ≥12–14 mmol/L.

In-depth characterisation of the urine metabolome in cats with and without urinary tract diseases

INTRODUCTION

Our understanding of the urine metabolome and its association with urinary tract disease is limited in cats.

OBJECTIVES

We conducted a case-control study to characterise the feline urine metabolome, investigate its association with chronic kidney disease (CKD) and feline idiopathic cystitis (FIC), and assess its compositional relationship with the urine microbiome.

METHODS

The urine metabolome of 45 owned cats, including 23 controls, 16 CKD, and 6 FIC cases, was characterised by an untargeted metabolomics approach using high-performance chemical isotope labelling liquid chromatography-mass spectrometry.

RESULTS

We detected 9411 unique compounds in the urine of controls and cases and identified 1037 metabolites with high confidence. Amino acids, peptides, and analogues dominated these metabolites (32.2%), followed by carbonyl compounds (7.1%) and carbohydrates (6.5%). Seven controls from one household showed a significant level of metabolome clustering, with a distinct separation from controls from other households (p value < 0.001). Owner surveys revealed that this cluster of cats was fed dry food only, whereas all but one other control had wet food in their diet. Accordingly, the diet type was significantly associated with the urine metabolome composition in our multivariate model (p value = 0.001). Metabolites significantly altered in this cluster included taurine, an essential amino acid in cats. Urine metabolome profiles were not significantly different in CKD and FIC cases compared with controls, and no significant compositional relationship was detected between the urine metabolome and microbiome.

CONCLUSION

Our study reveals in-depth diversity of the feline urine metabolome composition, and suggests that it can vary considerably depending on environmental factors.

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.

Serum and Fecal Amino Acid Profiles in Cats with Chronic Kidney Disease

The purpose of the study was to quantify serum and fecal amino acids (AA) in cats with chronic kidney disease (CKD) and compare to healthy cats. Thirty-five cats with International Renal Interest Society Stage 1–4 CKD and 16 healthy mature adult and senior client-owned cats were included in this prospective cross-sectional study. Sera were analyzed for 25 AA concentrations using an ion exchange chromatography AA analyzer with post column ninhydrin derivatization. Voided fecal samples were analyzed for 22 AA concentrations using liquid chromatography with tandem mass spectrometry. CKD cats had lower serum concentrations of phenylalanine (mean difference ± standard error of the mean: 12.7 ± 4.3 µM; p = 0.03), threonine (29.6 ± 9.2 µM; p = 0.03), tryptophan (18.4 ± 5.4 µM; p = 0.005), serine (29.8 ± 12.6 µM; p = 0.03), and tyrosine (11.6 ± 3.8 µM; p = 0.01) and higher serum concentrations of aspartic acid (4.7 ± 2.0 µM; p = 0.01), β-alanine (3.4 ± 1.2 µM; p = 0.01), citrulline (5.7 ± 1.6 µM; p = 0.01), and taurine (109.9 ± 29.6 µM; p = 0.01) when compared to healthy cats. Fecal AA concentrations did not differ between healthy cats and CKD cats. 3-Methylhistidine-to-creatinine did not differ between healthy cats with and without muscle loss. Cats with CKD IRIS Stages 1–4 have a deranged serum amino acid profile compared to healthy cats.

Drug-Dosing Adjustment in Dogs and Cats with Chronic Kidney Disease

Chronic kidney disease is a common kidney disorder in adult and aged dogs and cats; the management of associated complications and comorbidities generally requires a life-long medical treatment to ensure a good quality of life of affected patients. However, indications and the literature on drug dosing in dogs and cats with chronic kidney disease are often lacking. The aim of this review is to revise the current literature on drug dosing in canine and feline patients with renal impairment, with a special focus on the most commonly used medications to manage chronic kidney disease and possible comorbidities.

2022 ISFM Consensus Guidelines on the Management of Acute Pain in Cats

PRACTICAL RELEVANCE

Increases in cat ownership worldwide mean more cats are requiring veterinary care. Illness, trauma and surgery can result in acute pain, and effective management of pain is required for optimal feline welfare (ie, physical health and mental wellbeing). Validated pain assessment tools are available and pain management plans for the individual patient should incorporate pharmacological and non-pharmacological therapy. Preventive and multimodal analgesia, including local anaesthesia, are important principles of pain management, and the choice of analgesic drugs should take into account the type, severity and duration of pain, presence of comorbidities and avoidance of adverse effects. Nursing care, environmental modifications and cat friendly handling are likewise pivotal to the pain management plan, as is a team approach, involving the cat carer.

CLINICAL CHALLENGES

Pain has traditionally been under-recognised in cats. Pain assessment tools are not widely implemented, and signs of pain in this species may be subtle. The unique challenges of feline metabolism and comorbidities may lead to undertreatment of pain and the development of peripheral and central sensitisation. Lack of availability or experience with various analgesic drugs may compromise effective pain management.

EVIDENCE BASE

These Guidelines have been created by a panel of experts and the International Society of Feline Medicine (ISFM) based on the available literature and the authors' experience. They are aimed at general practitioners to assist in the assessment, prevention and management of acute pain in feline patients, and to provide a practical guide to selection and dosing of effective analgesic agents.

Is proteinuria a rare condition in apparently healthy and sick cats? A feline practice experience (2007-2018)

Background:

Proteinuria is assumed to be less frequent in cats than in dogs and is mainly associated with chronic kidney disease (CKD).

Aim:

The current study aimed to evaluate and compare urine protein-to-creatinine (UPC) values retrospectively in cats visited for comprehensive annual health check or for presenting systemic clinical signs related to CKD.

Methods:

UPC ratio was retrospectively evaluated in 112 owned cats, out of which 51 (45.5%) were apparently healthy cats according to their owners who visited for comprehensive annual health checks and 61 (54.5%) sick cats, presenting systemic clinical signs suggesting CKD, such as weight loss or polyuria/polydipsia, among others.

Results:

Based on UPC, the present study found that 54.5% of all cats included were borderline proteinuric or proteinuric, having increased UPC (UPC ≥ 0.2), with 35.7% included in the sick group and 18.7% in the health-check group. Increased UPC was also statistically associated with azotemia and isosthenuria (urinary-specific gravity between 1,008 and 1,035) in both sick and health-check groups of cats.

Conclusion:

Independent of the reason for their medical visit, it could be concluded that borderline proteinuria and proteinuria were statistically mainly related to CKD in cats. Furthermore, the measurement of UPC could be very useful in the detection and management of CKD in apparently healthy cats during a medical visit for annual health check irrespective of the age.

Analytical Validation of a New Immunoenzymatic Method for the Measurement of Feline Parathyroid Hormone in Cats with Chronic Kidney Disease

Simple Summary

Parathyroid hormone (PTH) is involved in many metabolic diseases, such as chronic kidney disease (CKD) and calcium disorders, and its measurement could be of clinical utility. However, available methods for the measurement of feline PTH are limited and not widely accessible. The aim of this study was to perform the analytical validation of a new method for PTH measurement in cats. Thirty-eight cats affected with CKD were included. The analytical protocol provided an evaluation of the precision, accuracy, and storage stability at different temperatures. The method investigated showed good precision and accuracy and good stability for 1 week of storage at freezing temperatures. The method was validated in cats, allowing its future use in diagnostic procedures.

Abstract

The determination of parathyroid hormone (PTH) in cats could be of clinical utility in many metabolic disorders, such as renal diseases, hypercalcemia, or nutritional imbalances. However, the available methods for the measurement of feline PTH are limited, not widely available, and need radioimmunoassays. The aim of this study was to perform the analytical validation of a new immunoenzymatic method for the measurement of feline PTH. Thirty-eight cats affected with chronic kidney disease (CKD) were included. PTH was measured using a two-site immunoenzymatic method validated in humans and dogs (ST AIA-PACK^® Intact PTH, Tosoh Bioscience, Tessenderlo, Belgium). The analytical validation provided the evaluation of precision (intra-assay and inter-assay), accuracy (linearity under dilution (LUD) and spike recovery test (SRT)), and the storage stability of serum samples at 20 °C, 4 °C, and −20 °C. The method showed good precision (intra-assay CVs (coefficient of variations) 3.19–9.61%; inter-assay CVs 9.26–15.28%). In both the intra- and inter-assays, the highest imprecision was found with the low concentration pool (9.61% and 15.28%) and accuracy (LUD and SRT r² = 0.99, p < 0.001), while the stability was optimal up until 7 days at −20 °C (−7.7%). The method was successfully validated in cats, allowing its future use in diagnostic procedures.

Impact of allogeneic feline uterine-derived mesenchymal stromal cell intravenous treatment on renal function of nephrectomized cats with chronic kidney disease

Chronic kidney disease (CKD) is a common condition and leading cause of mortality in cats. Mesenchymal stromal cells (MSCs) may have a therapeutic effect on CKD. The aim of this pilot study was to determine efficacy of systemically-administered allogeneic uterine tissue-derived MSCs (UMSCs) in cats with CKD. Eighteen renal-compromised, unilaterally nephrectomized cats received two doses of 3 × 10⁷ allogeneic UMSCs given intravenously (IV) with a 2-week dose interval. The primary endpoint was renal function, with treatment success defined by a 20% increase in glomerular filtration rate (GFR; iohexol clearance) and/or a 20% decrease in plasma creatinine in 50% of the cats. Secondary endpoints included diet and water consumption, body weight, urine characteristics, and adverse events. Treatment was well tolerated and associated with a statistically meaningful increase in GFR on Days 13, 28, 57, 99, 121 and 182, compared with baseline (P < 0.0001 for Days 13 to 99 inclusive; P = 0.0029 and P = 0.0225 for Days 121 and 182, respectively). Greater than 50% of the cats demonstrated a 20% increase in GFR on all days except Day 150, at which point GFR measurements were consistently above baseline. Statistically meaningful increases in diet and water consumption were observed. Substantial improvements in GFR were observed throughout the six-month evaluation period (excluding Day 150) in more than 50% of cats, thereby meeting the primary endpoint. Therefore, this IV-administered, allogeneic cellular therapy may support both renal function and clinical status of cats with CKD.

Age estimation using methylation-sensitive high-resolution melting (MS-HRM) in both healthy felines and those with chronic kidney disease

Age is an important ecological tool in wildlife conservation. However, it is difficult to estimate in most animals, including felines-most of whom are endangered. Here, we developed the first DNA methylation-based age-estimation technique-as an alternative to current age-estimation methods-for two feline species that share a relatively long genetic distance with each other: domestic cat (Felis catus; 79 blood samples) and an endangered Panthera, the snow leopard (Panthera uncia; 11 blood samples). We measured the methylation rates of two gene regions using methylation-sensitive high-resolution melting (MS-HRM). Domestic cat age was estimated with a mean absolute deviation (MAD) of 3.83 years. Health conditions influenced accuracy of the model. Specifically, the models built on cats with chronic kidney disease (CKD) had lower accuracy than those built on healthy cats. The snow leopard-specific model (i.e. the model that resets the model settings for snow leopards) had a better accuracy (MAD = 2.10 years) than that obtained on using the domestic cat model directly. This implies that our markers could be utilised across species, although changing the model settings when targeting different species could lead to better estimation accuracy. The snow leopard-specific model also successfully distinguished between sexually immature and mature individuals.

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.

Dysbiosis of the Urinary Bladder Microbiome in Cats with Chronic Kidney Disease

Although feline urinary tract diseases cause high morbidity and mortality rates, and subclinical bacteriuria is not uncommon, the feline urinary microbiome has not been characterized. We conducted a case-control study to identify the feline urinary bladder microbiome and assess its association with chronic kidney disease (CKD), feline idiopathic cystitis (FIC), and positive urine cultures (PUCs). Of 108 feline urine samples subjected to 16S rRNA gene sequencing, 48 (44.4%) samples reached the 500-sequence rarefaction threshold and were selected for further analysis, suggesting that the feline bladder microbiome is typically sparse. Selected samples included 17 CKD, 9 FIC, 8 PUC cases and 14 controls. Among these, 19 phyla, 145 families, and 218 genera were identified. Proteobacteria were the most abundant, followed by Firmicutes. Notably, four major urotypes were identified, including two urotypes predominated by Escherichia-Shigella or Enterococcus and two others characterized by relatively high alpha diversity, Diverse 1 and Diverse 2. Urotype was associated with disease status (P value of 0.040), with the Escherichia-Shigella-predominant urotype being present in 53% of CKD cases and in all of the Escherichia coli PUC cases. Reflecting these patterns, the overall microbial composition of CKD cases was more similar to that of E. coli PUC cases than to that of controls (P value of <0.001). Finally, PUC cases had microbial compositions distinct from those of controls as well as CKD and FIC cases, with significantly lower Shannon diversity and Faith’s phylogenetic diversity values.

IMPORTANCE Despite the clinical importance of urinary diseases in cats, the presence of resident urine microbes has not been demonstrated in cats, and the role of these microbes as a community in urinary health remains unknown. Here, we have shown that cats with and without urinary tract disease harbor unique microbial communities in their urine. We found no evidence to suggest that the bladder microbiome is implicated in the pathogenesis of feline idiopathic cystitis, a disease similar to bladder pain syndrome/interstitial cystitis in humans. However, cats with chronic kidney disease had dysbiosis of their bladder microbiome, which was predominated by Escherichia-Shigella and had a community structure similar to that of cats with Escherichia coli cystitis. These findings suggest that chronic kidney disease alters the bladder environment to favor Escherichia-Shigella colonization, potentially increasing the risk of overt clinical infection.

Feline Morbillivirus in Southern Italy: Epidemiology, Clinico-Pathological Features and Phylogenetic Analysis in Cats

Feline morbillivirus (FeMV) was isolated for the first time in 2012 with an association with chronic kidney disease (CKD) suggested. This study aimed at investigating in cats from southern Italy FeMV prevalence and risk factors for exposure to FeMV, including the relationship with CKD; sequencing amplicons and analyzing phylogeny of PCR positive samples. Blood serum, K₃EDTA blood and urine samples from 223 cats were investigated. Ten carcasses were also evaluated. FeMV RNA was detected in 2.4% (5/211) blood and 16.1% (36/223) urine samples. One carcass tested positive by qPCR_FeMV from kidney, urinary bladder, and submandibular lymph nodes. Antibodies against FeMV were detected in 14.5% (28/193) cats. We followed up 27 cats (13 FeMV positive cats) and documented in some cases urine shedding after up to 360 days. Older and foundling cats and cats living in rescue catteries, were more frequently infected with FeMV. A significant correlation between FeMV and higher serum creatinine values or low urine specific gravity was found. FeMV positivity was significantly associated with retroviral infection, and the presence of some clinical signs apart from CKD clinicopathological markers. Our study highlights the possibility of a link between FeMV exposure and CKD and a general impairment of feline health.

Renal scintigraphy as an early and efficient method for detecting loss of renal function in a cat

Case summary

A 6-year-old mixed-breed male cat was evaluated for a routine annual health assessment. No alterations on physical examination were observed other than mild pain on palpation of the right kidney. Complete blood count, serum biochemistry (including symmetric dimethylarginine), urinalysis and urine protein:creatinine ratio were within the reference intervals for the species. Abdominal ultrasonography showed the presence of asymmetric kidneys, decreased corticomedullary definition, presence of a cyst on the left kidney and moderate renal pelvis dilatation on the right kidney. Dynamic renal scintigraphy (technetium [^99mTc]-diethylenetriamine pentaacetic acid) revealed a single functioning kidney on the left. Static renal scintigraphy (^99mTc-dimercaptosuccinic acid) exhibited renal activity practically restricted to the left kidney (relative uptake was 99% for the left kidney and 1% for the right kidney). Results of renal scintigraphy showed that the left kidney was compensating for the lack of function of the right one. GFR was 2.17 ml/min/kg, which is considered subclinical renal insufficiency and is in accordance with the case, as the cat was asymptomatic and did not present alterations in laboratory parameters.

Relevance and novel information

Renal scintigraphy was an important tool to determine the loss of renal function in one of the kidneys and mild reduction of global GFR. In this case report, renal scintigraphy proved to be more sensitive in the assessment of renal function than other tests routinely performed.

2021 AAFP Feline Senior Care Guidelines

The '2021 AAFP Feline Senior Care Guidelines' are authored by a Task Force of experts in feline clinical medicine and serve as an update and extension of those published in 2009. They emphasize the individual patient evaluation and the process of aging, with references to other feline practice guidelines for a more complete discussion of specific diseases. Focusing on each cat encourages and empowers the owner to become a part of the cat's care every step of the way. A comprehensive discussion during the physical examination and history taking allows for tailoring the approach to both the cat and the family involved in the care. Videos and analysis of serial historical measurements are brought into the assessment of each patient. These Guidelines introduce the emerging concept of frailty, with a description and methods of its incorporation into the senior cat assessment. Minimum database diagnostics are discussed, along with recommendations for additional investigative considerations. For example, blood pressure assessment is included as a minimum diagnostic procedure in both apparently healthy and ill cats. Cats age at a much faster rate than humans, so practical timelines for testing frequency are included and suggest an increased frequency of diagnostics with advancing age. The importance of nutrition, as well as senior cat nutritional needs and deficiencies, is considered. Pain is highlighted as its own syndrome, with an emphasis on consideration in every senior cat. The Task Force discusses anesthesia, along with strategies to allow aging cats to be safely anesthetized well into their senior years. The medical concept of quality of life is addressed with the latest information available in veterinary medicine. This includes end of life considerations like palliative and hospice care, as well as recommendations on the establishment of 'budgets of care', which greatly influence what can be done for the individual cat. Acknowledgement is given that each cat owner will be different in this regard; and establishing what is reasonable and practical for the individual owner is important. A discussion on euthanasia offers some recommendations to help the owner make a decision that reflects the best interests of the individual cat.

Feline Morbillivirus Infection in Domestic Cats: What Have We Learned So Far?

Feline morbillivirus (FeMV) was identified for the first time in stray cats in 2012 in Hong Kong and, since its discovery, it was reported in domestic cats worldwide. Although a potential association between FeMV infection and tubulointerstitial nephritis (TIN) has been suggested, this has not been proven, and the subject remains controversial. TIN is the most frequent histopathological finding in the context of feline chronic kidney disease (CKD), which is one of the major clinical pathologies in feline medicine. FeMV research has mainly focused on defining the epidemiology, the role of FeMV in the development of CKD, and its in vitro tropism, but the pathogenicity of FeMV is still not clear, partly due to its distinctive biological characteristics, as well as to a lack of a cell culture system for its rapid isolation. In this review, we summarize the current knowledge of FeMV infection, including genetic diversity of FeMV strains, epidemiology, pathogenicity, and clinicopathological findings observed in naturally infected cats.

Liver-type fatty acid-binding protein and neutrophil gelatinase-associated lipocalin in cats with chronic kidney disease and hyperthyroidism

BACKGROUND

Liver-type fatty acid-binding protein (L-FABP) and neutrophil gelatinase-associated lipocalin (NGAL) are candidate biomarkers for the detection of early chronic kidney disease (CKD) in cats.

OBJECTIVE

To evaluate urinary and serum L-FABP and NGAL concentrations in CKD cats and in hyperthyroid cats before and after radioiodine (¹³¹ I) treatment.

ANIMALS

Nine CKD cats, 45 healthy cats and hyperthyroid cats at 3 time points including before (T0, n = 49), 1 month (T1, n = 49), and 11 to 29 months after (T2, n = 26) ¹³¹ I treatment.

METHODS

Cross-sectional and longitudinal study. Serum L-FABP (sL-FABP), serum NGAL (sNGAL), urinary L-FABP (uL-FABP), and urinary NGAL (uNGAL) were compared between the 3 groups and between hyperthyroid cats before and after treatment. Data are reported as median (min-max).

RESULTS

CKD cats had significantly higher sL-FABP (13.50 [3.40-75.60] ng/ml) and uL-FABP/Cr (4.90 [0.97-2139.44] µg/g) than healthy cats (4.25 [1.34-23.25] ng/ml; P = .01 and 0.46 [0.18-9.13] µg/g; P < .001, respectively). Hyperthyroid cats at T0 had significantly higher uL-FABP/Cr (0.94 [0.15-896.00] µg/g) than healthy cats (P < .001), thereafter uL-FABP/Cr significantly decreased at T2 (0.54 [0.10-76.41] µg/g, P = .002). For the detection of CKD, uL-FABP/Cr had 100% (95% confidence interval [CI], 66.4-100.0) sensitivity and 93.2% (95% CI, 81.3-98.6) specificity. There were no significant differences in sNGAL and uNGAL/Cr between the 3 groups.

CONCLUSIONS AND CLINICAL IMPORTANCE

L-FABP, but not NGAL, is a potential biomarker for the detection of early CKD in cats. Utility of uL-FABP to predict azotemia after treatment in hyperthyroid cats remains unknown.

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.

2021 AAHA/AAFP Feline Life Stage Guidelines

The guidelines, authored by a Task Force of experts in feline clinical medicine, are an update and extension of the AAFP-AAHA Feline Life Stage Guidelines published in 2010. The guidelines are published simultaneously in the Journal of Feline Medicine and Surgery (volume 23, issue 3, pages 211-233, DOI: 10.1177/1098612X21993657) and the Journal of the American Animal Hospital Association (volume 57, issue 2, pages 51-72, DOI: 10.5326/JAAHA-MS-7189). A noteworthy change from the earlier guidelines is the division of the cat's lifespan into a five-stage grouping with four distinct age-related stages (kitten, young adult, mature adult, and senior) as well as an end-of-life stage, instead of the previous six. This simplified grouping is consistent with how pet owners generally perceive their cat's maturation and aging process, and provides a readily understood basis for an evolving, individualized, lifelong feline healthcare strategy. The guidelines include a comprehensive table on the components of a feline wellness visit that provides a framework for systematically implementing an individualized life stage approach to feline healthcare. Included are recommendations for managing the most critical health-related factors in relation to a cat's life stage. These recommendations are further explained in the following categories: behavior and environmental needs; elimination; life stage nutrition and weight management; oral health; parasite control; vaccination; zoonoses and human safety; and recommended diagnostics based on life stage. A discussion on overcoming barriers to veterinary visits by cat owners offers practical advice on one of the most challenging aspects of delivering regular feline healthcare.

2021 AAHA/AAFP Feline Life Stage Guidelines

The guidelines, authored by a Task Force of experts in feline clinical medicine, are an update and extension of the AAFP-AAHA Feline Life Stage Guidelines published in 2010. The guidelines are published simultaneously in the Journal of Feline Medicine and Surgery (volume 23, issue 3, pages 211-233, DOI: 10.1177/1098612X21993657) and the Journal of the American Animal Hospital Association (volume 57, issue 2, pages 51-72, DOI: 10.5326/JAAHA-MS-7189). A noteworthy change from the earlier guidelines is the division of the cat's lifespan into a five-stage grouping with four distinct age-related stages (kitten, young adult, mature adult, and senior) as well as an end-of-life stage, instead of the previous six. This simplified grouping is consistent with how pet owners generally perceive their cat's maturation and aging process, and provides a readily understood basis for an evolving, individualized, lifelong feline healthcare strategy. The guidelines include a comprehensive table on the components of a feline wellness visit that provides a framework for systematically implementing an individualized life stage approach to feline healthcare. Included are recommendations for managing the most critical health-related factors in relation to a cat's life stage. These recommendations are further explained in the following categories: behavior and environmental needs; elimination; life stage nutrition and weight management; oral health; parasite control; vaccination; zoonoses and human safety; and recommended diagnostics based on life stage. A discussion on overcoming barriers to veterinary visits by cat owners offers practical advice on one of the most challenging aspects of delivering regular feline healthcare.

Multiple omental hemangiomas in a Himalayan cat: Incidental finding in a laparotomy

This report describes the occurrence of omental hemangioma in a five-year-old Himalayan cat. The cat was affected by hemorrhagic gastroenteritis caused by Fusobacterium necrophorum. Also, chronic renal failure (CRF) was demonstrated according to high levels of blood urine nitrogen (BUN), creatinine (Cr), as well as hypoproteinemia and anemia. In this respect, in urinalysis, urine specific gravity (USG) decreased while urea, creatinine and total protein levels increased. Moreover, the complete blood count (CBC) tests showed neutrophilia, monocytosis and lymphopenia. During an exploratory laparotomy, nine masses with a size of 1-5 mm and firm consistency were found to be scattered on the omentum. Histologically, the masses consisted of capillary-cavernous vessels with well-differentiated endothelial cells. No mitotic figures, hemorrhage, or necrosis were found, but there was focal lymphocytic infiltration in the parenchyma of the masses. Immunohistochemically, expression of vimentin and von Willebrand factor (vWF) was found in the endothelial cells, while the immunoreaction to smooth muscle actin (?SMA) was negative. These findings confirmed the diagnosis of hemangioma. To the best of the authors? knowledge, this is the first report of feline omental hemangioma.

Non-Renal Lesions of Uraemia in Domestic Cats

Uraemia is a clinical syndrome caused by an increase in uraemia-associated toxins in the bloodstream as a consequence of intrinsic kidney or lower urinary tract diseases. Cats seem to be more affected by urinary tract diseases than dogs, particularly considering that chronic kidney disease (CKD) is one of the most important conditions in cats. Considering the lack of information on the systemic lesions of uraemia in cats, the aim of this study was to investigate the prevalence and clinical and pathological aspects of non-renal lesions in uraemic cats, with special attention to the differences between cats and dogs. Cats necropsied between 2000 and 2019 (n = 1,330) were investigated for urinary tract diseases and non-renal lesions of uraemia. The prevalence of uraemic cats with non-renal lesions (n = 78) was 5.8%. Adult, elderly and male animals were predominantly affected. Anorexia, apathy and vomiting were the most common clinical signs and CKD was observed in the majority of uraemic cats. Pulmonary oedema was the most frequent non-renal lesion identified. In contrast with previous reports, haemorrhagic and ulcerative gastritis was frequently observed, whereas soft tissue mineralization and parathyroid hyperplasia were uncommon features. Fibrous osteodystrophy was not observed. Cats with urinary tract diseases did not have as wide a variety of non-renal uraemic lesions as uraemic dogs and multisystemic manifestation of uraemia was observed in only 24.4% of cases.