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Feline diabetes mellitus is a common endocrine disease with increasing prevalence. It shows similarities with human type 2 diabetes and is characterized by insulin resistance and deficient insulin secretion. Moreover, cats and humans belong to the very few species that form amyloid depositions in the pancreatic islets. However, little is known about cat islet function and no studies have addressed insulin secretion from isolated islets ex vivo. The aim of this study was to establish a protocol for isolation of islets of Langerhans from pancreata of cats euthanized due to disease, and to evaluate insulin secretion responses to various physiological and pharmacological stimuli. Collagenase digestion of pancreatic tissue from 13 non-diabetic cats and two cats with diabetic ketoacidosis yielded individual islets surrounded by a layer of exocrine tissue that was reduced after two days in culture. Histological examination showed islet amyloid in pancreatic biopsies from most non-diabetic and in one diabetic cat. Islets from non-diabetic cats cultured at 5.5 mM glucose responded with increased insulin secretion to 16.7 mM glucose, 30 mM K + and 20 µM of the sulfonylurea glipizide (2-3 times basal secretion at 3 mM glucose). The glucagon-like peptide-1 receptor agonist exendin-4 (100 nM) had no effect under basal conditions but potentiated glucose-triggered insulin release. Only one of nine islet batches from diabetic cats released detectable amounts of insulin, which was enhanced by exendin-4. Culture of islets from non-diabetic cats at 25 mM glucose impaired secretion both in response to glucose and K + depolarization. In conclusion, we describe a procedure for isolation of islets from cat pancreas biopsies and demonstrate that isolated cat islets secrete insulin in response to glucose and antidiabetic drugs. The study provides a basis for future ex vivo studies of islet function relevant to the understanding of the pathophysiology and treatment of feline diabetes., Competing Interests: Declaration of Competing Interest There are no conflicts of interest for any of the authors., (Copyright © 2023. Published by Elsevier Inc.)

Background: Biological variation (BV) of urinary (U) biochemical analytes has not been described in absolute terms, let alone as a ratio of the U-creatinine or fractional excretion in healthy dogs. These analytes are potential diagnostic tools for different types of kidney damage and electrolyte disorders in dogs., Objectives: We aimed to investigate the BV of specific gravity, osmolality, creatinine, urea, protein, glucose, chloride, sodium, potassium, calcium, and phosphate in urine from healthy pet dogs., Methods: Blood and urine samples from 13 dogs were collected once weekly for 8 weeks. Samples were analyzed in duplicate and in randomized order. For each sample, U-analyte and serum concentrations were measured, and U-analyte/U-creatinine and fractional excretion (FE) were calculated. Components of variance, estimated by restricted maximum likelihood, were used to determine within-subject variation (CV I ), between-subject variation (CV G ), and analytical variation (CV A ). Index of individuality (II) and reference change values were calculated., Results: CV I for all urine analytes varied between 12.6% and 35.9%, except for U-sodium, U-sodium/U-Cr, and FE-sodium, which had higher CV I s (59.5%-60.7%). For U-protein, U-sodium, U-potassium, U-sodium/U-creatinine, FE-urea, FE-glucose, FE-sodium, FE-potassium, and FE-phosphate II were low, indicating that population-based RIs were appropriate. The remaining analytes had an intermediate II, suggesting that population-based RIs should be used with caution., Conclusion: This study presents information on the biological variation of urinary and serum biochemical analytes from healthy dogs. These data are important for an appropriate interpretation of laboratory results., (© 2023 The Authors. Veterinary Clinical Pathology published by Wiley Periodicals LLC on behalf of American Society for Veterinary Clinical Pathology.)