Dogs develop complex multifactorial diseases analogous to humans, including inflammatory diseases, metabolic diseases, and cancer. Therefore, they represent relevant large animal models with the translational potential to human medicine.Organoids are 3-dimensional (3D), self-assembled structures derived from stem cells that mimic the microanatomy and physiology of their organ of origin. These translational in vitro models can be used for drug permeability and discovery applications, toxicology assessment, and to provide a mechanistic understanding of the pathophysiology of multifactorial chronic diseases. Furthermore, canine organoids can enhance the lives of companion dogs, providing input in various areas of veterinary research and facilitating personalized treatment applications in veterinary medicine. A small group of donors can create a biobank of organoid samples, reducing the need for continuous tissue harvesting, as organoid cell lines can be sub-cultured indefinitely.Herein, three protocols that focus on the culture of intestinal and hepatic canine organoids derived from adult stem cells are presented. The Canine Organoid Isolation Protocol outlines methods to process tissue and embedding of the cell isolate in a supportive matrix (solubilized extracellular membrane matrix). The Canine Organoid Maintenance Protocol describes organoid growth and maintenance, including cleaning and passaging along with appropriate timing for expansion. The Organoid Harvesting and Biobanking Protocol describes ways to extract, freeze, and preserve organoids for further analysis.

Dogs develop complex multifactorial diseases analogous to humans, including inflammatory diseases, metabolic diseases, and cancer. Therefore, they represent relevant large animal models with the translational potential to human medicine.Organoids are 3-dimensional (3D), self-assembled structures derived from stem cells that mimic the microanatomy and physiology of their organ of origin. These translational in vitro models can be used for drug permeability and discovery applications, toxicology assessment, and to provide a mechanistic understanding of the pathophysiology of multifactorial chronic diseases. Furthermore, canine organoids can enhance the lives of companion dogs, providing input in various areas of veterinary research and facilitating personalized treatment applications in veterinary medicine. A small group of donors can create a biobank of organoid samples, reducing the need for continuous tissue harvesting, as organoid cell lines can be sub-cultured indefinitely.Herein, three protocols that focus on the culture of intestinal and hepatic canine organoids derived from adult stem cells are presented. The Canine Organoid Isolation Protocol outlines methods to process tissue and embedding of the cell isolate in a supportive matrix (solubilized extracellular membrane matrix). The Canine Organoid Maintenance Protocol describes organoid growth and maintenance, including cleaning and passaging along with appropriate timing for expansion. The Organoid Harvesting and Biobanking Protocol describes ways to extract, freeze, and preserve organoids for further analysis.

This study was done to investigate epidemiological data and to report causes of lower urinary tract disease in a population of cats presented at the Small Animal Clinic of the University of Veterinary and Pharmaceutical Sciences Brno. Cats presented with lower urinary tract disease signs that had undergone a thorough physical examination and urinalysis (dipstick, urine specific gravity, urine sediment and dipslide urine culture) were included in the study. Urine samples were collected only by cystocentesis or sterile catheterization. Bloodwork, abdominal ultrasound, and abdominal radiographs were performed in 118 (66%), 170 (96%) and 9 (5%) patients, respectively. Cats that were treated with antibiotics or glucocorticoids during an episode of feline lower urinary tract disease (FLUTD) or during the foregoing month and which had undergone perineal urethrostomy or catheterization in private practice, were excluded. The study population consisted of 177 cats. Forty-one (23%) cats were diagnosed with a urethral plug, 26 cats (14%) with a urinary tract infection (UTI), 9 cats (5%) with urolithiasis and 101 cats (57%) with feline idiopathic cystitis (FIC). The cats diagnosed with UTI were significantly older than the cats with FIC, urethral plugs and urolithiasis. Urinary tract infection was diagnosed significantly more often in patients older than 10 years, and in female cats. The diagnosis of urethral plug was made significantly more often in males. Feline idiopathic cystitis and urethral plugs are the most common causes of FLUTD, and the causes are significantly age and sex-related.

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The permeable support system is typically used in conjunction with traditional twodimensional (2D) cell lines as an in vitro tool for evaluating the oral permeability of new therapeutic drug candidates. However, the use of these conventional cell lines has limitations, such as altered expression of tight junctions, partial cell differentiation, and the absence of key nuclear receptors. Despite these shortcomings, the Caco-2 and MDCK models are widely accepted and validated for the prediction of human in vivo oral permeability. Dogs are a relevant translational model for biomedical research due to their similarities in gastrointestinal anatomy and intestinal microflora with humans. Accordingly, and in support of parallel drug development, the elaboration of an efficient and accurate in vitro tool for predicting in vivo drug permeability characteristics both in dogs and humans is highly desirable. Such a tool could be the canine intestinal organoid system, characterized by three-dimensional (3D), self-assembled epithelial structures derived from adult stem cells.The (1) Permeable Support Seeding Protocol describes the experimental methods for dissociating and seeding canine organoids in the inserts. Canine organoid isolation, culture, and harvest have been previously described in a separate set of protocols in this special issue. Methods for general upkeep of the canine intestinal organoid monolayer are discussed thoroughly in the (2) Monolayer Maintenance Protocol.Additionally, this protocol describes methods to assess the structural integrity of the monolayer via transepithelial electrical resistance (TEER) measurements and light microscopy. Finally, the (3) Permeability Experimental Protocol describes the tasks directly preceding an experiment, including in vitro validation of experimental results.