Chronic Kidney Disease In Cats Research Articles

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

IntroductionAngiotensin-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.AimsOur 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.MethodsA 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).ResultsIn 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 importanceuACE2 concentration and activity exhibit varying changes as renal function declines, particularly in advanced CKD cats.

Risk factors and implications associated with ultrasound-diagnosed nephrocalcinosis in cats with chronic kidney disease.

Microscopic nephrocalcinosis is a common pathological feature of chronic kidney disease (CKD) in cats. Detection of macroscopic nephrocalcinosis using ultrasonography and its implications remain unexplored. Identify risk factors associated with ultrasound-diagnosed nephrocalcinosis and evaluate the influence of nephrocalcinosis on CKD progression. Thirty-six euthyroid client-owned cats with CKD. Prospective cohort study. Cats with CKD with and without ionized hypercalcemia were enrolled for renal ultrasonography. Cats were categorized according to the presence or absence of ultrasound-diagnosed nephrocalcinosis. Binary logistic regression was performed to identify nephrocalcinosis risk factors. The influence of nephrocalcinosis on CKD progression was assessed using linear mixed models. Ultrasound-diagnosed nephrocalcinosis was evident in 61% of CKD cats overall, with increased prevalence (81%) in those with hypercalcemia. At enrollment, higher blood ionized calcium concentration (odds ratio [OR], 1.27 per 0.1 mg/dL; P = .01), plasma phosphate concentration (OR, 1.16 per 0.1 mg/dL; P = .05), plasma creatinine concentration (OR, 1.29 per 0.1 mg/dL; P = .02) and alanine aminotransferase activity (OR, 2.08 per 10 U/L; P = .04) were independent nephrocalcinosis risk factors. The rate of change in log-transformed fibroblast growth factor-23 differed significantly between groups (P = .04). Cats with CKD and nephrocalcinosis had increasing plasma creatinine concentrations (.03 ± .01 mg/dL/month; P = .04) and phosphate concentrations (.06 ± .02 mg/dL/month; P < .001) and decreasing body weight (.02 ± .01 kg/month; P < .001) over time. Nephrocalcinosis is prevalent in cats with CKD, especially in those with hypercalcemia. This pathological feature appears to be associated with CKD progression in cats.

Diagnostic informativeness of biopsy for chronic kidney disease in cats

The biopsy is a diagnostic method that allows in vivo sampling of kidney tissue material for histopathological examination to identify structural changes in the organ. The study aims to study the informativeness of intravital diagnosis of stage II chronic kidney disease (according to IRIS) in cats based on the results of histological and histochemical studies of biopsies. A kidney biopsy was performed on two cats aged 6 and 8 years. Research methods: histological (hematoxylin and eosin, Heidenhain test) and histochemical (PAS reaction, Gomori (PAMS)). The diagnosis of chronic kidney disease was made based on history, clinical symptoms, and blood and urine test results. Based on the biopsy, acute extracapillary serous-desquamative glomerulonephritis was established in cats with II-stage chronic kidney disease, which was characterized by vacuolar dystrophy of renal tubule epitheliocytes, desquamation of glomerular capsule epithelium. In addition, lymphoplasmacytic infiltration of the renal stroma, thickening of the Shumlyansky-Bowman capsule with significant deposition of PAS-positive substances, the collapse of the glomerular loops, and focal atrophy of the proximal tubules of the kidney pronounced extra capillary desquamation of the glomerular epithelium, segmentation of the vascular glomerulus, and dystrophy of single tubules were noted. The detected changes in kidney biopsies of cats in the II stage of chronic kidney disease are characteristic of this pathology, which makes it possible to develop and carry out effective treatment of animals promptly and improve their quality of life.

Association between pancreatitis and chronic kidney disease in cats: a retrospective review of 154 cats presented to a specialty hospital between October 1, 2017, and October 1, 2022.

To investigate an association between pancreatitis and chronic kidney disease (CKD) in cats. 154 client-owned cats: 77 cats with pancreatitis and 77 control cats with no evidence of pancreatitis. Retrospective record review from October 1, 2017, to October 1, 2022, including cats with gastrointestinal clinical signs, pancreatic lipase immunoreactivity (PLI) ≥ 8.8 μg/L or PLI 4.5 to 8.7 μg/L with sonographic evidence of pancreatitis. Control cats had a PLI ≤ 4.4 μg/L with no sonographic evidence of pancreatitis. Cats with pancreatitis had significantly higher International Renal Interest Society CKD stages than controls (P < .001; OR, 13 [95% CI, 6.3 to 31]), and mean creatinine was on average 0.79 mg/dL (95% CI, 0.56 to 1.0) higher than controls (P < .001; age covariate ANCOVA, P = .003). Odds of CKD in cats with pancreatitis compared to controls increased significantly with age (P = .002). Cats aged 10 to < 15 years and 15 to 20 years with pancreatitis had significantly higher prevalence of CKD stage 2 to 4 compared to controls (P < .001; OR, 10.9 [95% CI, 3.4 to 44]; and P = .001; OR, 66 [95% CI, 4.6 to > 1,000], respectively). Cats with pancreatitis had significantly more sonographic renal infarcts (P = .004; OR, 6.9 [95% CI, 1.8 to 46]) and concurrent diabetes mellitus (P = .002; OR, 6 [95% CI, 1.9 to 27]). Cats with pancreatitis were fed more exclusively dry-food diets compared to controls (P = .014). Pancreatitis is associated with CKD in cats. Investigating and treating these diseases concurrently early in the disease process may reduce morbidity and mortality due to progressive disease and expensive hospitalizations. Renal infarcts may be associated with pancreatitis in cats without overt cardiac disease.

Investigating the Efficacy of Kidney-Protective Lactobacillus Mixture-Containing Pet Treats in Feline Chronic Kidney Disease and Its Possible Mechanism.

Microbiota-based strategies are a novel auxiliary therapeutic and preventative way of moderating chronic kidney disease (CKD). Lactobacillus mixture (Lm) was previously demonstrated to exert a renal-protective function in the CKD mice model. The efficacy of probiotics in pet foods is a relatively new area of study, and thus verifying the potential health benefits is necessary. This study evaluated the efficacy of Lm treats in feline CKD and elucidated the mechanisms underlying host-microbe interactions. CKD cats (2 and 3 stages) were administrated probiotic pet treats daily (10 g) for 8 weeks. The results demonstrated that during the eight weeks of Lm administration, creatinine was reduced or maintained in all cats with CKD. Similarly, gut-derived uremic toxin (GDUT), indoxyl sulfate (IS), were potential clinical significance in IS after Lm treatment (confidence intervals = 90%). The life quality of the cats also improved. Feline gut microbiome data, metabolic functional pathway, and renal function indicator analyses revealed the possible mechanisms involved in modulating CKD feline microbial composition. Further regulation of the microbial functions in amino acid metabolism after Lm administration contributed to downregulating deleterious GDUTs. The current study provides potential adjuvant therapeutic insights into probiotic pet foods or treats for pets with CKD.

The effectiveness of feed additives in chronic kidney disease in cats

Chronic kidney disease in cats is one of the most common diseases. The main direction of palliative therapy for chronic kidney disease  and  extending  the  survival  time  of cats  is  to  limit  phosphates  in  the  diet  and normalize the phosphorus content in the animal’s body. In order to reduce phosphates, phosphate  binders  are  used  -  substances whose mechanism of action is to bind excess phosphate  ions  in  the  gastrointestinal  tract, which  prevents  their  entry  into  the  blood-stream. The purpose of the study is to analyze  the  effectiveness  of  feed  additives “Urdetox” and “Ipakitine” in a comparative aspect in the palliative treatment of chronic kidney disease in cats. Determination of the biological activity of the proposed feed additive for cats with CKD in the form of tablets was  carried  out  on  the  basis  of  veterinary clinics in the city. Volgograd, St. Petersburg, Moscow, in the period 2021-2022. The objects  of  the  study  were  cats  whose  owners complained of loss of animal body weight, often  a  general  depressed  state,  decreased appetite,  periodic  vomiting,  frequent  urination, dull hair. The diagnosis and experiment were  carried  out  by  collecting  anamnestic data, determining clinical signs and laboratory data - a general urine test and a biochemical  analysis  of  blood  serum.  Studies  have shown that feed additives containing a phosphate binder and a detoxicant help eliminate the  main  clinical  manifestations  of  chronic renal failure. The introduction of the essential amino acid -taurine into the feed additive in the form of Urdetox tablets, as well as the accuracy of dosing and ease of use increase the effectiveness of its biological action.

Inflammatory Status and Chronic Kidney Disease in Cats: Old and New Inflammatory Markers—A Pilot Prospective Study

This prospective study aimed to evaluate inflammatory status in cats affected by chronic kidney disease (CKD) at IRIS stages 2–4, using serum amyloid A (SAA) and the erythrocyte sedimentation rate (ESR) as inflammatory markers. Thirty-two cats with CKD and ten clinically healthy cats (i.e., control group) were enrolled. The recording of signalment data, complete physical examinations, and abdominal ultrasonography were performed for each animal. Additionally, ESR levels, complete blood count, clinical chemistry (including SAA determination), serum protein electrophoresis, and complete urinalysis were executed. This study’s results showed that mean ESR and SAA concentrations in cats with CKD were statistically higher compared to those of the control group (p = 0.0005 and p = 0.007, respectively). The SAA concentration was significantly increased at IRIS stages 2, 3, and 4 compared to the control group. Meanwhile, the ESR was significantly higher in cats at IRIS stages 3 and 4 (p = 0.0003 and p = 0.0007, respectively), but not at IRIS stage 2, compared to the control group. These results provide evidence that feline CKD is associated with a systemic inflammatory status. Moreover, the rise in ESR appears to be more linked to advanced stages of the disease and could, therefore, correlate with the uremic condition.

Effectiveness of complex treatment of cats for chronic kidney disease

Treatment of cats with chronic kidney disease should be aimed at slowing the progression of the disease, which contributes to the preservation of residual kidney function, the elimination of clinical signs of CKD, and the quality of life of sick animals. During the II stages of chronic kidney disease in cats, hyporexia (60 %), polyuria and polydipsia (50 %), anemia of mucous membranes (60 %), impaired coordination of movements (30 %), vomiting and ulcerative stomatitis (40 %), an increase in serum levels of creatinine and urea (P &gt; 0.001), the level of symmetric dimethylarginine (P &lt; 0.001), the concentration of cystatin C (P &gt; 0.001), a decrease in the rate of glomerular filtration, the level of total calcium (P &lt; 0.001), an increase in the level of inorganic Phosphorus and Potassium. Arterial hypertension was established in 8 cats; the risk was moderate (148 ± 4.7 / 98 ± 3.8 mmHg). Changes in the physical properties and chemical composition of urine have been established. The application of complex treatment of cats with II stages of chronic kidney disease for 14 days contributed to the restoration of appetite, increased motor activity, the absence of anemia of visible mucous membranes and vomiting, and a decrease in the level of polyuria and polydipsia was established. Hematological indicators improved, the content of symmetric dimethylarginine in blood serum (Р &lt; 0.001), Cystatin C (Р &lt; 0.001), the level of total calcium (Р &lt; 0.001) normalized, azotemia decreased (Р &lt; 0.001), the rate of glomerular filtration increased (Р &lt; 0.001), the level of inorganic Phosphorus and Potassium (Р &lt; 0.001). An increase (Р &lt; 0.001) in the relative density of urine and a decrease in the content of protein and creatinine were noted in the urine. For arterial hypertension in cats with chronic kidney disease, life-long therapy is indicated, which is adjusted according to the needs and condition of the animal.

Use of molidustat, a hypoxia-inducible factor prolyl hydroxylase inhibitor, in chronic kidney disease-associated anemia in cats.

Erythropoietic effects of molidustat, a hypoxia-inducible factor prolyl hydroxylase (HIF-PH) inhibitor, were previously demonstrated in healthy cats. To evaluate the safety and erythropoietic effects of daily PO administration of molidustat in anemic cats with chronic kidney disease (CKD). Twenty-one client-owned CKD cats (4-17 years old) with anemia. Multicenter field study; randomized, masked, and placebo-controlled. Cats were treated PO once daily for 28 days with suspensions of control product (CP; n = 6) or 5 mg/kg of molidustat (n = 15). Hematocrit (HCT) was evaluated at weekly intervals. Individual cat treatment success was defined as a ≥4% point increase in HCT compared to baseline. Control group mean HCT remained low throughout the study (20.1%-23.4%). Mean HCT of molidustat-treated cats increased weekly, and a significant increase compared to baseline (23.6%) was first observed on Day 21 (27.3%; P < .001; 95% confidence interval [CI], 1.69-5.67). Compared to CP group, mean HCT was significantly higher on Day 21 (27.3% vs 20.1%; P < .001; 95% CI, 2.91-10.75) but not significantly higher on Day 28 (27.8% vs 23.4%; P = .06; 95% CI, -0.23 to 9.88). The number of individual treatment successes on Day 28 was higher among remaining molidustat-treated cats (7/14) compared to remaining control cats (1/5), but there was no significant difference between groups. Daily PO molidustat administration may stimulate a clinically relevant erythropoietic response in anemic cats with CKD. This HIF-PH inhibitor may be an alternative for managing anemia in cats compared to recombinant EPO treatment.

Detection of feline morbillivirus in cats with symptoms of acute febrile infection

Feline morbillivirus (FeMV) was identified for the first time in cats in 2012 in Hong Kong. Although its association with chronic kidney disease in cats has attracted the attention of researchers, its clinical significance as an acute infection has not been reported. Previously, we reported FeMV detection using next-generation sequence-based comprehensive genomic analysis of plasma samples from cats with suspected acute febrile infections. Here, we conducted an epidemiological survey to detect FeMV by quantitative reverse transcription polymerase chain reaction (qRT-PCR) using blood samples from cats in Japan. FeMV was detected in 32/102 blood samples (31.4%) from cats with suspected acute viral infections. Most of the FeMV-positive cats had clinical findings consistent with acute viral infections, including fever, leukopenia, thrombocytopenia and jaundice. No FeMV was detected in healthy cats or clinically ill cats that visited veterinary hospitals. Phylogenetic analysis classified FeMV L genes into various FeMV subtypes. We also necropsied a FeMV-positive cat that died of a suspected acute infection. On necropsy, FeMV was detected in systemic organs, including the kidneys, lymph nodes and spleen by qRT-PCR and immunohistochemical staining. These results suggest that FeMV infections may cause acute symptomatic febrile infections in cats. A limitation of this study was that the involvement of other pathogens that cause febrile illnesses could not be ruled out and this prevented a definitive conclusion that FeMV causes febrile disease in infected cats. Further studies that include experimental infections are warranted to determine the pathogenicity of FeMV in cats.

Measurement of Ghrelin as a Marker of Appetite Dysregulation in Cats with and without Chronic Kidney Disease.

Appetite abnormalities and weight loss are important comorbidities in the treatment of chronic kidney disease (CKD) in cats. Ghrelin, a key hormone involved in the regulation of appetite and metabolism, is a potential marker of appetite dysregulation in cats with CKD. The aim of this study was to compare the plasma concentrations of acylated, desacyl, and total ghrelin in normal cats and cats with CKD. Storage methodology was investigated prior to evaluating ghrelin concentrations in normal and CKD cats to facilitate clinical sample collection. Twelve normal cats and twelve cats with CKD were enrolled. Plasma acylated and total ghrelin concentrations were measured using radioimmunoassay. Desacyl ghrelin was calculated (total ghrelin minus acylated ghrelin). Cats with CKD had significantly increased total ghrelin and calculated desacyl ghrelin concentrations in comparison to normal cats (p < 0.0001 and p = 0.0001). There was no significant difference in active ghrelin concentrations between groups. Both total ghrelin and calculated desacyl ghrelin were significantly correlated with serum creatinine concentrations (p < 0.0001, r = 0.70 and p < 0.0001, r = 0.73). Elevated plasma desacyl ghrelin concentrations in cats with CKD provides evidence for dysregulation of appetite in feline CKD.

Comparison of cystocentesis versus home sampling to determine urinary protein: Creatinine ratio and urine specific gravity in cats.

Urinalysis is necessary for the diagnostic evaluation of chronic kidney disease in cats. Performing cystocentesis is not always feasible, but data comparing urine obtained by cystocentesis in the clinic with voided samples collected at home are lacking in cats. To compare urinary protein:creatinine ratio (UPC) and urine specific gravity (USG) and to detect clinically relevant changes in proteinuria substage or urine concentration between urine collected at home and in-clinic by cystocentesis in cats. Ninety-two healthy and diseased client-owned cats. Prospective study. Owners collected voided urine at home and within 1 to 15 hours, cystocentesis was performed in the clinic. In a subset of motivated owners, 55% succeeded in collecting urine at home. Overall, UPC was higher (mean ±SD difference = 0.09 ±0.22; P < .001) and USG was lower (mean ±SD difference = -0.006 ±0.009; P < .001) in cystocentesis samples than in voided urine. Substantial agreement existed between sampling methods for UPC (weighted к = 0.68) and USG (к = 0.64) categories. A different proteinuria substage (UPC < 0.2, 0.2-0.4, >0.4) was present in paired urine samples from 28% of cats. In 18% of cats, urine concentrating ability (USG < or ≥1.035) differed between both samples. Home sampling of urine is a valid alternative to cystocentesis in cats. However, because clinically relevant differences in UPC and USG were present in 28% and 18% of cats, respectively, by the same collection method for monitoring each cat is advised.

Reasoning for obligatory preclinical diagnostics of feline chronic kidney disease

Diseases of the urinary system of various etiologies are common in all species of animals and over time, they can lead to the development of chronic kidney disease (CKD) as the progressive process in which renal function gradually decreases over several years. In modern veterinary medicine, there is a problem of a steeply increase in cases of chronic kidney disease in cats. Pathology occurs most often in aged animals, but recent studies have registered cases of chronic renal dysfunction in young ones as well. In chronic kidney disease the kidneys do not work well for a long time, causing a number of changes in the body. Unfortunately, early symptoms are often missed by pet owners and the disease is not noticed for a long time. In most cases, the diagnosis of chronic kidney disease is established only when effective treatment is no longer possible or ineffective and treatment is able to maintain the homeostasis of the body only to a certain extent and for a short time. Undoubtedly, this approach to the diagnosis and treatment of kidney disease requires changes. In view of the fact that the duration of the preclinical stage of CKD can reach several years, the goals of our study were to show the benefits of early diagnosis of chronic kidney disease in cats and the introduction of a new concept of systematic body screening of clinically healthy animals and animals at risk. Also, the goals were to delay the moment of the kidneys compensatory reserve exhaustion and onset of clinical symptoms, which require constant symptomatic and replacement therapy. Reducing the percentage of early mortality of patients and the maximum possible increase in the duration of the preclinical stage of renal pathology were also aimed at. Efforts were also aimed at reducing the percentage of early mortality of patients and the maximum possible increase in the duration of the preclinical stage of renal pathology. Since nephroprotective therapy at the preclinical stage is highly effective in most clinical cases and allows to significantly slow down the progression of any chronic nephropathy, including CKD, there is a need for the formation of innovative diagnostic approaches at the early stages of the disease. It is proposed to conduct a cumulative assessment of the anamnesis in animals from risk groups, monitoring the level of creatinine in the blood serum, complete clinical analysis of urine, ultrasound examination of the kidneys, measurement of protein concentration, since these indicators have not only prognostic value and determine the tactics of treatment, but are also important factors pathogenesis of CKD. Since each parameter will not provide a complete state of the disease, since none of them is 100 % specific, an integrated approach to the early diagnosis of chronic kidney disease is needed for. It is necessary to take into account all the methods listed above, as well as monitoring the condition of the body of animals that have contracted any viral or bacterial infection, or have acute kidney damage, diabetes, hypertension, or metabolic disorders.

A remnant kidney surgery model in cats induces acute and chronic outcomes that mimic spontaneous chronic kidney disease.

To report acute and chronic outcomes of cats with chronic kidney disease (CKD) induced by a remnant kidney model. 32 purpose-bred cats (n = 15 female, n = 17 male). Cats underwent a 2-stage reduction in renal mass through partial arterial ligation of 1 kidney (day 28) and delayed contralateral nephrectomy (day 0), targeting an 11/12th functional nephrectomy. Acute (days -28 - 29) survival and renal function parameters were compared over time, and the latter were evaluated as predictors for acute mortality. Chronic (days 30 to >1,100) survival, renal function, and morphology were described. Acutely, renal function deteriorated in all cats (mean ± SD baseline and day 28 serum creatinine mean concentration, 1.13 ± 0.23 mg/dL and 3.03 ± 1.20 mg/dL, respectively; P < .001; and GFR, 3.22 mL/min/kg ± 0.12 and 1.21 mL/min/kg ± 0.08, respectively; P < .001). Seven (22%) cats were euthanized after because of clinical signs of uremia after contralateral nephrectomy. Prenephrectomy renal function tests were not significant indicators for survival during this acute phase. Twenty-five cats entered the chronic phase. Ten cats were euthanized at a median of 163 days from nephrectomy because of progressive renal dysfunction. Median survival times were significantly different when stratified by acute kidney injury grade at day 29. Cats in the chronic phase had clinical courses similar to cats with naturally occurring CKD, and most (13/15) were in CKD stage 2. The remnant kidney model is effective at reducing kidney function to an extent that mimics important characteristics of spontaneous CKD in cats.

Ультрасонографическая оценка почек у кошек с хроническими нефропатиями

Abstract. The purpose of the study was to establish an ultrasonographic picture of the upper urinary system in cats with chronic kidney disease at different stages and their prognostic significance. Research methods. The study involved 40 cats of different sex, age and breed with an established diagnosis of chronic kidney disease from stage 1 to stage 4, 10 animals in each group. The staging of the stage was based on the concentration of the serum creatinine level. All animals underwent ultrasonographic examination of the urinary system on the ChisonQBit 11 apparatus with a high-frequency linear sensor in longitudinal and cross sections. The nature of structural changes in the kidneys as a result of ultrasonographic examination were correlated with the stage of the disease. Scientific novelty. Chronic kidney disease is one of the most common pathologies in cats older than 7 years. The disease is progressive, which proves the need for early detection and preparation of therapeutic and diagnostic measures to prolong and improve the life of the animal. Ultrasound diagnostics is included in the diagnostic plan, which allows to identify animals with structural changes in the kidneys, but is not decisive in the diagnosis and stage of chronic kidney disease in cats. Results. In cats at stage 1 of chronic kidney disease, ultrasound changes in the structure of the kidneys were absent in 60 % of cases, ultrasound signs of polycystic and hyperechogenic medullary rim (ring) were detected in 10 % of cases. In cats at stage 2, ultrasound changes of the kidneys were absent in 30 % of cases, signs of nephrolithiasis (concretions in the projection of the pelvis without signs of obstruction) were found in 20 % of cases, and signs of nephrosclerosis/hypoplasia unilaterally were found in 10 % of cases. At stage 3, diffuse kidney changes were detected in 100 % of cases, signs of nephrosclerosis/hypoplasia in 40 % of cases, nephrolithiasis in 20 %, polycystic disease in 10 % of cases. At stage 4, diffuse changes were present in 100 %, signs of nephrosclerosis/hypoplasia in 30 %, and nephrolithiasis in 10 % of cases. Thus, there are no specific signs that allow us to establish the stage of chronic kidney disease in cats according to the results of ultrasonographic examination.

Prospective evaluation of a telmisartan suppression test as a diagnostic tool for primary hyperaldosteronism in cats.

In a previous study, telmisartan suppressed aldosterone secretion in healthy cats but not in cats with primary hyperaldosteronism (PHA). Telmisartan suppresses aldosterone secretion in middle-aged healthy cat and cats with diseases that may result in secondary hyperaldosteronism, but not in those with PHA. Thirty-eight cats: 5 with PHA; 16 with chronic kidney disease (CKD), subclassified as hypertensive (CKD-H) or non-hypertensive (CKD-NH); 9 with hyperthyroidism (HTH); 2 with idiopathic systemic arterial hypertension (ISH); and 6 healthy middle-aged cats. Prospective, cross-sectional study. Serum aldosterone concentration, potassium concentration, and systolic blood pressure were measured before and 1 and 1.5 hours after PO administration of 2 mg/kg of telmisartan. The aldosterone variation rate (AVR) was calculated for each cat. No significant difference in the minimum AVR was observed among groups (median [quartile 1 (Q1); quartile 3 (Q3)]: 25 [0; 30]; 5 [-27; -75]; 10 [-6; -95]; 53 [19; 86]; 29 [5; 78]) for PHA, CKD, HTH, ISH, and healthy cats, respectively (P = .05). Basal serum aldosterone concentration (pmol/L) was significantly higher in PHA cats (median [Q1; Q3]: 2914 [2789; 4600]) than in CKD-H cats (median [Q1; Q3]: 239 [189; 577], corrected P value = .003) and CKD-NH cats (median [Q1; Q3]: 353 [136; 1371], corrected P value = .004). The oral telmisartan suppression test using a single dose of 2 mg/kg telmisartan did not discriminate cats with PHA from healthy middle-aged cats or cats with diseases that may result in secondary hyperaldosteronism.

Ultrasonographic kidney length-to-abdominal aortic diameter for the diagnosis of feline chronic kidney disease: A preliminary study.

Chronic kidney disease (CKD) is one of the most important diseases in cats. This study aimed to compare the ultrasonographic kidney length-to-abdominal aortic diameter (K/AO) ratio between healthy and CKD cats and investigate the correlation between K/AO and blood results. Fifteen healthy cats and 15 CKD cats were included in this clinically prospective study. All cats were evaluated for radiographic and ultrasonographic K, radiographic K-to-second lumbar length ratio (K/L2), and K/AO, indirect systolic blood pressure and plasma creatinine (Cr), blood urea nitrogen (BUN), and symmetric dimethyl arginine (SDMA). The radiographic and ultrasonographic kidney lengths of CKD were significantly shorter than those of healthy cats (p < 0.05 and p < 0.05, respectively). The average K/L2 and K/AO were significantly lower in CKD than in healthy cats (p < 0.01 and p < 0.001, respectively). The K/AO had a strong negative correlation with plasma Cr (r = -0.7682, p < 0.0001), BUN (r = -0.6175, p < 0.001), and SDMA (r = -0.589, p < 0.001). However, K/L2 had a moderate negative correlation with plasma Cr (r = -0.5866, p < 0.001), BUN (r = -0.4884, p < 0.01), and SDMA (r = -0.5404, p < 0.01). The optimal cutoff value of K/AO (<10.71) had higher sensitivity and specificity than K/L2 for identifying feline CKD. Kidney length-to-abdominal aortic diameter could be a better and more promising parameter than the K/L2 ratio for evaluating kidney size in cats with CKD.

Effect of laboratory and sample storage factors on urinary protein:creatinine ratios and clinical decision making in cats.

Urinary protein:creatinine ratio (UPC) results affect the diagnosis, prognosis, and therapy of chronic kidney disease in cats. To investigate the interlaboratory and intralaboratory variability and the effect of storage on UPC and International Renal Interest Society (IRIS) proteinuria substaging in cats. Healthy and diseased client-owned cats. Prospective study. Urine of 60 cats was randomly sent to 4 (of 9) participating laboratories (to assess interlaboratory variability) and per cat, 2 laboratories each received 2 aliquots (to determine intralaboratory variability). Samples of 23 cats were analyzed in the same laboratory the day of collection, after preservation at 22°C for 1 day and at 4°C during 1-7 days (short-term storage) and at -24°C and -80°C for 6-12 months (long-term storage). Storage conditions were compared by equivalence testing. UPCs showed good interclass correlation (ICC-inter, 0.90) and excellent intraclass correlation (ICC-intra, 0.99). However, in 30/60 (50%) cats at least 1 of 4 laboratories assigned a different IRIS proteinuria substage. Urinary protein:creatinine ratio remained stable with short-term storage, but not after 6 months storage at -24°C and after 12 months storage at -24°C or -80°C. Long-term storage caused a change in IRIS proteinuria substage in 27% of cats, whereas a shift occurred only in 4% of cats during short-term storage. Laboratory choice for UPC measurement can result in different IRIS substaging for the same cat, whereas urine storage at room temperature for 1 day or in the refrigerator for up to 7 days does not clinically affect UPC.

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

Hypoxia is a key driver of fibrosis and is associated with capillary rarefaction in humans. Characterize capillary rarefaction in cats with chronic kidney disease (CKD). Archival kidney tissue from 58 cats with CKD, 20 unaffected cats. 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. 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). 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.

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.