Plasma N-terminal pro-atrial natriuretic peptide (NT-proANP) concentration increases with progression of myxomatous mitral valve disease (MMVD) in dogs. This multicentre, prospective study compared plasma NT-proANP, N-terminal pro-brain natriuretic peptide (NT-proBNP), ANP, and cardiac troponin I (cTnI) concentrations in dogs with MMVD for their characteristics and discriminatory ability to detect cardiac dilatation and congestive heart failure (CHF). Thirty-six healthy dogs and 69 dogs with MMVD were included. Clinical variables were obtained via physical examination, thoracic radiography, and echocardiography. The discriminatory ability of each cardiac biomarker (CB) to determine the presence or absence of cardiac dilatation (event 1) and CHF (event 2) was evaluated using the receiver operating characteristic curves. Plasma NT-proANP, NT-proBNP, and ANP concentrations showed a significant association with the left atrium/aorta ratio ( P <0.01). The area under the curve of plasma NT-proANP and NT-proBNP concentrations were 0.72 and 0.75, respectively in event1 and 0.72 and 0.76, respectively in event2. Plasma NT-proANP and NT-proBNP concentrations showed sensitivity 80.0 and 80.0%; specificity 67.6 and 64.7% in event1 (cutoff value; 8,497.81 pg/ml and 1,453.00 pmol/l, respectively) and sensitivity 85.7 and 81.0%; specificity 60.4 and 64.6% in event2 (cutoff value; 8,684.33 pg/ml and 1,772.00 pmol/l, respectively). In dogs with MMVD, plasma NT-proANP, NT-proBNP, and ANP concentrations increase with left atrial enlargement. Particularly, plasma NT-proANP and NT-proBNP concentrations appeared to be equally useful in the discriminatory ability to detect cardiac dilatation and CHF.

Objectives The aim of this study was to investigate serum fibroblast growth factor (FGF)-23 concentrations in young and mature adult cats with chronic kidney disease (CKD). Methods The present study retrospectively investigated the serum samples and medical records of 1–8-year-old clinically healthy cats (control group, n = 7) and cats with CKD (n = 54). Cats with CKD were divided into four stages based on serum creatinine concentrations, according to the International Renal Interest Society (IRIS) CKD guidelines. Serum FGF-23 concentrations were compared between cats in the control group, IRIS stages 1, 2 and 3–4 CKD. Continuous variables were analysed using correlations and multiple linear regression. Results Serum FGF-23 concentrations were significantly higher in cats with IRIS stages 1, 2 and 3–4 CKD, compared with those in the control group ( P = 0.02, P = 0.002 and P = 0.002, respectively). Additionally, serum FGF-23 concentrations in cats with IRIS stages 3–4 CKD had higher serum FGF-23 concentrations than those with IRIS stages 1 and 2 CKD ( P = 0.04 and P = 0.02, respectively). In the multiple linear regression analysis, serum urea nitrogen concentration, serum phosphorus concentration and blood ionised calcium concentration were independent variables predicting serum FGF-23 concentration. Conclusions and relevance Serum FGF-23 concentrations in younger cats with CKD increased in early-stage CKD and were associated with mineral metabolic markers, as also occurs in geriatric cats.

Objectives This study investigated whether serum fibroblast growth factor (FGF)-23 concentrations are associated with serum total calcium (tCa) and blood ionised calcium (iCa) concentrations in cats with chronic kidney disease (CKD) and upper urolithiasis. Methods Serum samples and the medical records of cats with CKD with nephroliths, ureteroliths or both were investigated retrospectively. Cats with a serum creatinine concentration >250 μmol/l and/or a serum phosphorus concentration ⩾1.50 mmol/l were excluded. Based on cut-offs for serum tCa (2.70 mmol/l) or blood iCa (1.40 mmol/l), cats were divided into the following groups: total hypercalcaemia (H-tCa) (>2.70 mmol/l) and total normocalcaemia (N-tCa) (⩽2.70 mmol/l) groups, or ionised hypercalcaemia (H-iCa) (>1.40 mmol/l) and ionised normocalcaemia (N-iCa) (⩽1.40 mmol/l) groups, respectively. Serum FGF-23 concentrations were compared between groups and correlation analysis was performed. Results Thirty-two cats with CKD and upper urolithiasis were included. Serum FGF-23 concentrations in the H-tCa group (median 573 pg/ml [range 125–3888]; n = 12) were significantly higher compared with the N-tCa group (median 245 pg/ml [range 94–627]; n = 20) ( P = 0.001). Serum FGF-23 concentrations in the H-iCa group (median 1479 pg/ml [range 509–3888]; n = 6) increased significantly compared with the N-iCa group (median 245 pg/ml [range 94–637]; n = 26) ( P <0.001). Serum FGF-23 concentrations significantly correlated with serum tCa ( r = 0.511, P = 0.003) and blood iCa concentrations ( r = 0.425, P = 0.015) but not serum creatinine ( r = 0.279, P = 0.122) or phosphorus concentrations ( r = 0.208, P = 0.253). Conclusions and relevance Increased serum FGF-23 concentrations were associated with hypercalcaemia independently of creatinine and phosphate status in cats with CKD and upper urolithiasis.

Objectives This study aimed to define the prevalence of upper urolithiasis in cats with chronic kidney disease (CKD) in a referral population, and to compare urinary calcium:creatinine ratio (UCa:Cr), and total and ionised calcium between cats with CKD with and without upper urolithiasis. Methods The medical records of cats diagnosed with CKD were reviewed for signalment, body weight, diet and prevalence of upper urolithiasis. Cats with preserved urine samples were further classified into two groups: urolithiasis group (upper urolithiasis identified by abdominal ultrasonography) and control group (CKD of unknown origin). Serum biochemical analysis, CKD stage, blood gas analysis, urine specific gravity and UCa:Cr were compared between groups using a two-sample t-test or Mann–Whitney U-test for continuous variable and a χ2 test or Fisher’s exact test for categorical variables. Multivariable binary logistic regression analysis was used to identify risk factors. Results Among the 140 cats with CKD, the prevalence of upper urolithiasis was 73%. Fifty cats (5, 29 and 16 cats with CKD stages 1, 2 and 3, respectively) with urine samples met the inclusion criteria and were included in the analysis. Among cats with CKD, being purebred (odds ratio [OR] = 81.56; P = 0.03) and being fed dry food only (OR = 25.06; P = 0.001) were identified as independent upper urolithiasis risk factors; those with upper urolithiasis were more likely to be exclusively fed with urine-acidifying food ( P <0.001) and have increased serum ionised calcium (iCa) ( P = 0.044), fractional excretion of calcium ( P = 0.45) and UCa:Cr ( P = 0.005) than cats with CKD without upper urolithiasis. Conclusions and relevance Cats with CKD that were purebred, fed dry food and fed urine-acidifying food only often had upper urolithiasis. A higher UCa:Cr may be a result of increased serum iCa and may cause upper urolithiasis.

Background Fibroblast growth factor (FGF)‐23 is increased first in the sequence of changes associated with chronic kidney disease (CKD)‐mineral and bone disorder. Thus, its measurement may serve as a predictive indicator of incident hyperphosphatemia. Objectives To investigate whether serum FGF‐23 concentration in normophosphatemic dogs with CKD is associated with the risk of the subsequent development of hyperphosphatemia and CKD progression. Animals Forty‐two normophosphatemic dogs with CKD. Methods Blood samples and medical records were retrospectively investigated. Hyperphosphatemia was defined as a serum phosphorous concentration >5.0 mg/dL. Progression was defined as a >1.5‐fold increase in serum creatinine concentration. The time periods and hazard ratios for these outcomes were assessed using Kaplan‐Meier analysis, log‐rank test, and univariate Cox regression analysis. The variables associated with the outcomes in the univariate analysis were included in the multivariate Cox regression model with backward selection. Results Serum FGF‐23 concentration >528 pg/mL was associated with a shorter time to development of hyperphosphatemia ( P < .001) and CKD progression ( P < .001). In multiple Cox regression analysis, increased FGF‐23 concentration remained a significant variable associated with these outcomes ( P < .05). Conclusions and Clinical Importance Increased FGF‐23 concentration in normophosphatemic dogs with CKD was associated with significant risk of development of hyperphosphatemia, independent of CKD stage, and of the progression of CKD. Future research focusing on whether interventions that decrease FGF‐23 secretion will slow the development of hyperphosphatemia and CKD progression is needed.