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Background: Hyperthyroidism can complicate (mask) the diagnosis of chronic kidney disease (CKD) because it increases glomerular filtration rate and decreases body muscle mass, both of which can lower serum creatinine concentrations. Currently, there is no clinical test that can reliably predict which hyperthyroid cats have concurrent azotemic CKD that will become apparent after treatment of the hyperthyroidism. Objectives: To investigate serum symmetric dimethylarginine (SDMA) concentration as a potential marker of masked azotemia in untreated hyperthyroid cats. Animals: Two hundred and sixty‐two hyperthyroid cats and 206 aged‐matched, clinically normal cats. Methods: Prospective study. We measured creatinine, urea nitrogen, SDMA, T4, and TSH concentrations before and 1, 3, and 6 months after treatment with radioiodine (131I) and classified 131I‐treated cats as azotemic or nonazotemic based on persistent, post‐treatment creatinine concentrations >2.1 mg/dL. Groups were compared via nonparametric tests, and diagnostic accuracy was determined by receiver operating characteristic analysis and logistic regression. Results: No hyperthyroid cats were azotemic before treatment, but 42 (16%) became azotemic when rechecked at 4–8 months (median, 6 months) after 131I treatment; of these, 14 had high SDMA concentrations before treatment. As a diagnostic test for pre‐azotemic (masked) CKD in untreated hyperthyroid cats, SDMA showed a sensitivity of 33.3% and specificity of 97.7%. Conclusions and Clinical Importance: Finding a high serum SDMA concentration in a hyperthyroid cat can help predict development of azotemia after treatment. The test has high diagnostic test specificity (few false‐positive results) but relatively low sensitivity (fails to predict azotemia in most hyperthyroid cats). [ABSTRACT FROM AUTHOR]

Evaluation of canine renal biopsy tissue has generally relied on light microscopic (LM) evaluation of hematoxylin and eosin–stained sections ranging in thickness from 3 to 5 µm. Advanced modalities, such as transmission electron microscopy (TEM) and immunofluorescence (IF), have been used sporadically or retrospectively. Diagnostic algorithms of glomerular diseases have been extrapolated from the World Health Organization classification scheme for human glomerular disease. With the recent establishment of 2 veterinary nephropathology services that evaluate 3-µm sections with a panel of histochemical stains and routinely perform TEM and IF, a standardized objective species-specific approach for the diagnosis of canine glomerular disease was needed. Eight veterinary pathologists evaluated 114 parameters (lesions) in renal biopsy specimens from 89 dogs. Hierarchical cluster analysis of the data revealed 2 large categories of glomerular disease based on the presence or absence of immune complex deposition: The immune complex–mediated glomerulonephritis (ICGN) category included cases with histologic lesions of membranoproliferative or membranous patterns. The second category included control dogs and dogs with non-ICGN (glomerular amyloidosis or focal segmental glomerulosclerosis). Cluster analysis performed on only the LM parameters led to misdiagnosis of 22 of the 89 cases—that is, ICGN cases moved to the non-ICGN branch of the dendrogram or vice versa, thereby emphasizing the importance of advanced diagnostic modalities in the evaluation of canine glomerular disease. Salient LM, TEM, and IF features for each pattern of disease were identified, and a preliminary investigation of related clinicopathologic data was performed. [ABSTRACT FROM AUTHOR]

Background: Circulating creatinine and symmetric dimethylarginine (SDMA) are biomarkers of kidney function that have been used variously to define stable vs progressive chronic kidney disease (CKD). Slope monitoring of inverse biomarker values (creatinine -1 or SDMA -1 ) has shown promise, but quantitative criteria to distinguish stable vs progressive CKD using this approach are lacking., Objective: Assessment of creatinine -1 and SDMA -1 slope cutoffs to distinguish stable vs progressive CKD., Animals: One hundred ten clinically healthy university staff-owned dogs and 29 male colony dogs with progressive X-linked hereditary nephropathy (XLHN)., Methods: Retrospective analysis combining 2 prospective observational studies, 1 tracking kidney function biomarkers in healthy dogs (HDs) to a maximum of 3 years, and 1 tracking kidney function biomarkers in male colony dogs with progressive XLHN to a maximum of 1 year. The minimum slope of creatinine -1 or SDMA -1 as measured using the IDEXX SDMA test from HD was assigned as the slope cutoff for stable kidney function., Results: The stable vs progressive slope cutoff was -0.0119 week × dL/mg for creatinine -1 and -0.0007 week × dL/μg for SDMA -1 ., Conclusions and Clinical Importance: In the studied CKD population, progressive dysfunction can be distinguished from stable kidney function by using the slope of creatinine -1 or SDMA -1 . These criteria may serve to characterize CKD in other cohorts of dogs and to establish guidelines for degrees of progression rate in dogs with naturally occurring CKD., (© 2023 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)

Background: Early identification of dogs with progressive vs stable chronic kidney disease (CKD) might afford opportunity for interventions that would slow progression. However, currently no surrogate biomarker reliably predicts CKD progression., Hypothesis/objectives: Urinary cystatin B (uCysB), a novel kidney injury biomarker, predicts progressive disease in International Renal Interest Society (IRIS) CKD Stage 1., Animals: Seventy-two dogs, including 20 dogs from 4 university centers with IRIS CKD Stage 1, with IDEXX symmetric dimethylarginine (SDMA) concentration up to 17 μg/dL and no systemic comorbidities, and 52 clinically healthy staff-owned dogs from a fifth university center., Methods: A multicenter prospective longitudinal study was conducted between 2016 and 2021 to assess uCysB concentration in IRIS CKD Stage 1 and control dogs. Dogs were followed to a maximum of 3 years (control) or 25 months (CKD). Stage 1 IRIS CKD was classified as stable or progressive using the slope of 1/SDMA, calculated from 3 timepoints during the initial 90-day period. Dogs with slope above or below -0.0007 week × dL/μg were classified as stable or progressive, respectively. Mixed effects modeling was used to assess the association between uCysB and progression rate., Results: Estimates of first visit uCysB results predictive of active ongoing kidney injury based on the mixed effects models were 17 ng/mL for control, 24 ng/mL for stable CKD, and 212 ng/mL for progressive CKD (P < .001)., Conclusions and Clinical Importance: Urinary cystatin B differentiated stable vs progressive IRIS CKD Stage 1. Identification of dogs with progressive CKD may provide an opportunity for clinicians to intervene early and slow progression rate., (© 2023 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)

Elevated concentrations of serum phosphate are linked with progression and increased case fatality rate in animals and humans with chronic kidney disease. Elevated concentrations of serum phosphate can be a risk factor for development of renal and cardiovascular diseases or osteoporosis in previously healthy people. In rodents, an excess intake of dietary phosphorus combined with an inverse dietary calcium : phosphorus ratio (<1 : 1) contributes to renal calcification. Renal injury also has occured in cats fed experimental diets supplemented with highly soluble phosphate salts, especially in diets with inverse calcium : phosphorus ratios. However, not all phosphorus sources contribute similarly to this effect. This review, which focuses on cats, summarizes the published evidence regarding phosphorus metabolism and homeostasis, including the relative impact of different dietary phosphorus sources, and their impact on the kidneys. No data currently shows that commercial cat foods induce renal injury. However, some diets contain high amounts of phosphorus relative to recommendations and some have inverse Ca : P ratios and so could increase the risk for development of kidney disease. While limiting the use of highly soluble phosphates appears to be important, there are insufficient data to support a specific upper limit for phosphate intake. This review also proposes areas where additional research is needed in order to strengthen conclusions and recommendations regarding dietary phosphorus for cats., (© 2020 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)

Background: Primary hypertriglyceridemia is a common condition in older Miniature Schnauzers that recently has been associated with proteinuria and underlying glomerular pathology, particularly glomerular lipid thromboemboli. Consequences of glomerular disease can include hypertension, thromboembolic disease, and cardiac disease. The incidence of these sequelae in Miniature Schnauzers with hypertriglyceridemia-associated proteinuria (HTGP) is unknown., Objective: To investigate prevalence of hypertension, decreased antithrombin III activity, and cardiac disease in Miniature Schnauzers with and without HTGP., Animals: Thirty-two Miniature Schnauzers ≥7 years old., Methods: Prospective case-control study. Data collected from dogs included a CBC, biochemistry panel, urinalysis, urine protein-to-creatinine ratio, urine cortisol-to-creatinine ratio, serum total thyroxine concentration, fasting serum triglyceride concentration, indirect blood pressure, antithrombin III activity, and serum cardiac troponin I concentration. Results from dogs with HTGP (serum triglyceride concentration ≥ 100 mg/dL and urine protein-to-creatinine ratio >0.5) were statistically compared to normotriglyceridemic, nonproteinuric dogs., Results: Eighteen of the 32 dogs (56%) had primary hypertriglyceridemia. Of those dogs, 8 of 18 had proteinuria. None of the HTGP dogs were azotemic or hypoalbuminemic. Serum albumin concentration, alkaline phosphatase activity, and cholesterol concentration were significantly increased in dogs with HGTP compared to those without HGTP. No increased risk of hypertension, decreased antithrombin III activity, or cardiac disease was noted. Limited data from 8 dogs with HTGP showed no development of hypoalbuminemia or azotemia over a median follow-up period of 18 months., Conclusions and Clinical Importance: Geriatric Miniature Schnauzers with HGTP may have a good prognosis overall, and are not typically azotemic or hypoalbuminemic., (Copyright © 2017 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

This is a retrospective case series of 27 dogs with emphysematous cystitis. Medical records from two veterinary teaching hospitals from 1992 to 2014 were reviewed. The aims of the study were to determine imaging findings, common underlying disease processes, and prevalent bacterial species and their antimicrobial susceptibility patterns in dogs with emphysematous cystitis. The most common lower urinary tract sign was hematuria. Gas was detected in the wall and lumen of the urinary bladder in 14 of 27 dogs (51.9%), in only the wall of the bladder in 9 of 27 dogs (33%), and in only the lumen of the bladder in 4 of 27 dogs (14.8%). Comorbid diseases were identified in all but one case. The most common comorbid disease processes were diabetes mellitus in 33% of dogs, neurologic disease in 26% of dogs, and adrenal disease in 19% of dogs. Bacterial isolates included Escherichia coli, Enterococcus spp., Klebsiella pneumoniae, Proteus mirabilis, Streptococcus spp., and Actinomyces spp. Enterococcus spp. were always isolated in mixed infections with gas-producing bacterial species. During the period of study, most isolates were predicted to be susceptible to beta-lactam drugs, but updated veterinary breakpoints suggest that fluoroquinolones or trimethoprim-sulfamethoxazole would be more appropriate choices for empiric therapy.