{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,4]],"date-time":"2026-08-04T01:45:22Z","timestamp":1785807922597,"version":"3.56.0"},"reference-count":46,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2025,9,30]],"date-time":"2025-09-30T00:00:00Z","timestamp":1759190400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["www.mdpi.com"],"crossmark-restriction":true},"short-container-title":["Animals"],"abstract":"<jats:p>Background: Right heart failure (RHF) in dogs is marked by pathological fluid redistribution and extracellular fluid (ECF) accumulation, which intensifies cardiac work-load and disrupts systemic homeostasis. This study aimed to validate the clinical utility of phase angle (PhA), a key biomarker derived from bioelectrical impedance analysis (BIA), as a non-invasive and real-time indicator of fluid distribution abnormalities in canine RHF. PhA reflects cellular integrity and fluid balance, making it a promising tool for detecting ECF accumulation, one of the hallmark features of RHF. Additionally, the study assessed the feasibility and clinical applicability of the InBody M20 device in veterinary cardiology, supporting its potential role in monitoring and managing fluid-related complications in dogs with RHF. Methods: A total of 110 canine patients presenting to the Tokyo University of Agriculture and Technology Veterinary Hospital were enrolled and categorized into three groups: right-sided heart failure (RHF), left-sided heart failure (LHF), and healthy controls. Phase angle (PhA) was measured using the InBody M20 device, and plasma osmolality (OSM) was also assessed. Additionally, the effects of body weight and age on PhA values were analyzed to account for potential confounding factors. Results: Dogs in the RHF group exhibited significantly lower phase angle (PhA) values and higher plasma osmolality (OSM) compared to those in the LHF and control groups. A strong positive correlation was observed between PhA and OSM (r = 0.9211, p &lt; 0.0001). Additionally, PhA measured at 5 kHz demonstrated a significant negative correlation with body weight (r = \u20130.4536, p = 0.0007), while PhA at 50 kHz showed a significant negative correlation with age (r = \u20130.3219, p = 0.0176). Conclusions: PhA is a reliable and non-invasive biomarker for assessing extracellular fluid accumulation and diagnosing right heart failure in dogs. Its strong correlation with plasma osmolality, as well as its associations with body weight and age, highlights its clinical relevance for comprehensive fluid status evaluation. The findings support the feasibility and applicability of using the InBody M20 device in veterinary cardiology to monitor and manage fluid-related complications in canine patients.<\/jats:p>","DOI":"10.3390\/ani15192877","type":"journal-article","created":{"date-parts":[[2025,9,30]],"date-time":"2025-09-30T16:43:54Z","timestamp":1759250634000},"page":"2877","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Phase Angle as a Non-Invasive Biomarker of Fluid Overload in Canine Right Heart Failure: A Bioelectrical Impedance Approach"],"prefix":"10.3390","volume":"15","author":[{"given":"Zongru","family":"Li","sequence":"first","affiliation":[{"name":"Veterinary Teaching Hospital, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6256-4539","authenticated-orcid":false,"given":"Ahmed S.","family":"Mandour","sequence":"additional","affiliation":[{"name":"Department of Animal Medicine (Internal Medicine), Faculty of Veterinary Medicine, Suez Canal University, Ismailia 41522, Egypt"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1953-4294","authenticated-orcid":false,"given":"Ahmed","family":"Farag","sequence":"additional","affiliation":[{"name":"Veterinary Teaching Hospital, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-8778-3923","authenticated-orcid":false,"given":"Tingfeng","family":"Xu","sequence":"additional","affiliation":[{"name":"Veterinary Teaching Hospital, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0004-8304-2667","authenticated-orcid":false,"given":"Kazuyuki","family":"Terai","sequence":"additional","affiliation":[{"name":"Veterinary Teaching Hospital, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2514-695X","authenticated-orcid":false,"given":"Kazumi","family":"Shimada","sequence":"additional","affiliation":[{"name":"Veterinary Teaching Hospital, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5291-925X","authenticated-orcid":false,"given":"Lina","family":"Hamabe","sequence":"additional","affiliation":[{"name":"Veterinary Teaching Hospital, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3124-912X","authenticated-orcid":false,"given":"Aimi","family":"Yokoi","sequence":"additional","affiliation":[{"name":"Veterinary Teaching Hospital, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9948-6490","authenticated-orcid":false,"given":"Ryou","family":"Tanaka","sequence":"additional","affiliation":[{"name":"Veterinary Teaching Hospital, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,9,30]]},"reference":[{"key":"ref_1","first-page":"1","article-title":"Analysis of Body Composition: A Critical Review of the Use of Bioelectrical Impedance Analysis","volume":"2","author":"Mialich","year":"2014","journal-title":"Int. J. Clin. Nutr."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"173.e17","DOI":"10.1016\/j.jamda.2014.10.024","article-title":"The Bioimpedance Phase Angle Predicts Low Muscle Strength, Impaired Quality of Life, and Increased Mortality in Old Patients with Cancer","volume":"16","author":"Norman","year":"2015","journal-title":"J. Am. Med. Dir. Assoc."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"10895","DOI":"10.3390\/s140610895","article-title":"The Theory and Fundamentals of Bioimpedance Analysis in Clinical Status Monitoring and Diagnosis of Diseases","volume":"14","author":"Khalil","year":"2014","journal-title":"Sensors"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"676","DOI":"10.1016\/j.cardfail.2008.04.005","article-title":"The Usefulness of Bioelectrical Impedance Analysis in Differentiating Dyspnea Due to Decompensated Heart Failure","volume":"14","author":"Parrinello","year":"2008","journal-title":"J. Card. Fail."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"61","DOI":"10.1159\/000210663","article-title":"Relationship between Extracellular Water Fraction of Total Body Water Estimated by Bioimpedance Spectroscopy and Cardiac Troponin T in Chronic Haemodialysis Patients","volume":"28","author":"Park","year":"2009","journal-title":"Blood Purif."},{"key":"ref_6","first-page":"35","article-title":"Hypertrophy-Type Resistance Training Improves Phase Angle in Young Adult Men and Women","volume":"38","author":"Ribeiro","year":"2017","journal-title":"Int. J. Sports Med."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"147","DOI":"10.1007\/s11606-013-2585-z","article-title":"Phase Angle, Frailty and Mortality in Older Adults","volume":"29","author":"Hall","year":"2014","journal-title":"J. Gen. Intern. Med."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"361","DOI":"10.1002\/ajpa.10301","article-title":"Reliability and Variability of Bioimpedance Measures in Normal Adults: Effects of Age, Gender, and Body Mass","volume":"122","author":"Dittmar","year":"2003","journal-title":"Am. J. Phys. Anthropol. Off. Publ. Am. Assoc. Phys. Anthropol."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Langer, R.D., Silva, A.M., Borges, J.H., Cirolini, V.X., P\u00e1scoa, M.A., Guerra-J\u00fanior, G., and Gon\u00e7alves, E.M. (2019). Physical Training over 6 Months Is Associated with Improved Changes in Phase Angle, Body Composition, and Blood Glucose in Healthy Young Males. Am. J. Hum. Biol., 31.","DOI":"10.1002\/ajhb.23275"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"732","DOI":"10.1111\/ggi.13241","article-title":"Phase Angle Measured by Electrical Bioimpedance and Global Cardiovascular Risk in Older Adults","volume":"18","author":"Saad","year":"2018","journal-title":"Geriatr. Gerontol. Int."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"3889","DOI":"10.1007\/s11259-024-10555-1","article-title":"Bioelectrical Impedance Analysis (BIA) Detects Body Resistance Increase in Dogs Undergoing Blood Donation","volume":"48","author":"Nisini","year":"2024","journal-title":"Vet. Res. Commun."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1757S","DOI":"10.1093\/jn\/132.6.1757S","article-title":"Evaluation of Multifrequency Bioelectrical Impedance Analysis for the Assessment of Extracellular and Total Body Water in Healthy Cats","volume":"132","author":"Elliott","year":"2002","journal-title":"J. Nutr."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"72","DOI":"10.1111\/jvim.14885","article-title":"Longitudinal Analysis of Quality of Life, Clinical, Radiographic, Echocardiographic, and Laboratory Variables in Dogs with Preclinical Myxomatous Mitral Valve Disease Receiving Pimobendan or Placebo: The EPIC Study","volume":"32","author":"Boswood","year":"2018","journal-title":"J. Vet. Intern. Med."},{"key":"ref_14","unstructured":"Boon, J.A. (1998). Manual of Veterinary Echocardiography, Wiley-Blackwell."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1142","DOI":"10.1111\/j.1939-1676.2009.0392.x","article-title":"Guidelines for the Diagnosis and Treatment of Canine Chronic Valvular Heart Disease","volume":"23","author":"Atkins","year":"2009","journal-title":"J. Vet. Intern. Med."},{"key":"ref_16","unstructured":"Fox, P.R. (1988). Canine and Feline Cardiology, Churchill Livingstone."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1292\/jvms.62.109","article-title":"Examination of Quantitative Analysis and Measurement of the Regurgitation Rate in Mitral Valve Regurgitation by the \u201cProximal Isovelocity Surface Area\u201d Method","volume":"62","author":"Doiguchi","year":"2000","journal-title":"J. Vet. Med. Sci."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"S215","DOI":"10.1016\/j.jvc.2014.09.004","article-title":"Congenital Heart Defects in Cats: A Retrospective Study of 162 Cats (1996\u20132013)","volume":"17","author":"Tidholm","year":"2015","journal-title":"J. Vet. Cardiol."},{"key":"ref_19","unstructured":"Kittleson, M.D. (1998). Small Animal Cardiovascular Medicine, Mosby. Congenit. Pulmonic Stenosis."},{"key":"ref_20","first-page":"82","article-title":"Japanese Society of Veterinary Cardiology, Veterinary Cardiology Certification Program, Lecture (25) Valvular heart disease in dogs and cats: Treatment of mitral regurgitation","volume":"3","author":"Koyama","year":"2014","journal-title":"Vet. Circ. Small Anim. Cardiol. J."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"364","DOI":"10.2460\/javma.2000.216.364","article-title":"Influence of Open Surgical Correction on Intermediate-Term Outcome in Dogs with Subvalvular Aortic Stenosis: 44 Cases (1991\u20131998)","volume":"216","author":"Orton","year":"2000","journal-title":"J. Am. Vet. Med. Assoc."},{"key":"ref_22","first-page":"65","article-title":"Japanese Society of Veterinary Cardiology, Veterinary Cardiology Certification Program, Lecture 5, Congenital Heart Disease: Left-to-Right Shunt Disease","volume":"4","author":"Chimura","year":"2015","journal-title":"Vet. Circ. Small Anim. Cardiol. J."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"309","DOI":"10.1177\/0148607106030004309","article-title":"Phase Angle from Bioelectrical Impedance Analysis: Population Reference Values by Age, Sex, and Body Mass Index","volume":"30","author":"Danielzik","year":"2006","journal-title":"J. Parenter. Enter. Nutr."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"263","DOI":"10.21037\/cdt-20-302","article-title":"Pathophysiology of Heart Failure","volume":"11","author":"Schwinger","year":"2021","journal-title":"Cardiovasc. Diagn. Ther."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"465","DOI":"10.1042\/cs0620465","article-title":"The Renin-Angiotensin-Aldosterone System, Antidiuretic Hormone and Sympathetic Nerve Activity in an Experimental Model of Congestive Heart Failure in the Dog","volume":"62","author":"Riegger","year":"1982","journal-title":"Clin. Sci."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Ishikawa, S., and Funayama, H. (2023). Hyponatremia Associated with Congestive Heart Failure: Involvement of Vasopressin and Efficacy of Vasopressin Receptor Antagonists. J. Clin. Med., 12.","DOI":"10.3390\/jcm12041482"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"51","DOI":"10.1111\/jvim.15998","article-title":"Correction of serum chloride concentration in dogs with congestive heart failure","volume":"35","author":"Adin","year":"2021","journal-title":"J. Vet. Intern. Med."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"53","DOI":"10.1111\/jvim.15662","article-title":"Role of electrolyte concentrations and renin-angiotensin-aldosterone activation in the staging of canine heart disease","volume":"34","author":"Adin","year":"2020","journal-title":"J. Vet. Intern. Med."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1439","DOI":"10.1378\/chest.109.6.1439","article-title":"Early Diagnosis and Estimation of Pulmonary Congestion and Edema in Patients with Left-Sided Heart Diseases from Histogram of Pulmonary CT Number","volume":"109","author":"Kato","year":"1996","journal-title":"Chest"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"e263","DOI":"10.1016\/j.jacc.2021.12.012","article-title":"2022 AHA\/ACC\/HFSA Guideline for the Management of Heart Failure: A Report of the American College of Cardiology\/American Heart Association Joint Committee on Clinical Practice Guidelines","volume":"79","author":"Heidenreich","year":"2022","journal-title":"J. Am. Coll. Cardiol."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Abassi, Z., Khoury, E.E., Karram, T., and Aronson, D. (2022). Edema Formation in Congestive Heart Failure and the Underlying Mechanisms. Front. Cardiovasc. Med., 9.","DOI":"10.3389\/fcvm.2022.933215"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"465","DOI":"10.1007\/s11154-022-09757-2","article-title":"The Role of Bioelectrical Phase Angle in Patients with Heart Failure","volume":"24","author":"Scicchitano","year":"2023","journal-title":"Rev. Endocr. Metab. Disord."},{"key":"ref_33","first-page":"387","article-title":"Body Composition Measurements: Interpretation Finally Made Easy for Clinical Use","volume":"6","author":"Kyle","year":"2003","journal-title":"Curr. Opin. Clin. Nutr. Metab. Care"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"1009","DOI":"10.1007\/s10741-022-10276-0","article-title":"Right Heart Failure in Left Heart Disease: Imaging, Functional, and Biochemical Aspects of Right Ventricular Dysfunction","volume":"28","author":"Ghio","year":"2023","journal-title":"Heart Fail. Rev."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"381","DOI":"10.1007\/s11154-022-09780-3","article-title":"Bioimpedance Basics and Phase Angle Fundamentals","volume":"24","author":"Ward","year":"2023","journal-title":"Rev. Endocr. Metab. Disord."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"563","DOI":"10.1007\/s11154-023-09803-7","article-title":"Future Lines of Research on Phase Angle: Strengths and Limitations","volume":"24","author":"Bellido","year":"2023","journal-title":"Rev. Endocr. Metab. Disord."},{"key":"ref_37","unstructured":"King, K.C., and Goldstein, S. (2022). Congestive Heart Failure and Pulmonary Edema. StatPearls [Internet], StatPearls Publishing."},{"key":"ref_38","doi-asserted-by":"crossref","unstructured":"Heymsfield, S. (2005). Human Body Composition, Human Kinetics.","DOI":"10.5040\/9781492596950"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"877","DOI":"10.1152\/ajplegacy.1966.210.4.877","article-title":"Correlation between Body Fluid Volumes and Body Weight in the Rat","volume":"210","author":"Fernandez","year":"1966","journal-title":"Am. J. Physiol. Content"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"49","DOI":"10.1093\/ajcn\/82.1.49","article-title":"Bioelectrical Impedance Analysis: Population Reference Values for Phase Angle by Age and Sex","volume":"82","author":"Barros","year":"2005","journal-title":"Am. J. Clin. Nutr."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"227","DOI":"10.1016\/j.rvsc.2009.07.009","article-title":"Effect of Breed on Body Composition and Comparison between Various Methods to Estimate Body Composition in Dogs","volume":"88","author":"Jeusette","year":"2010","journal-title":"Res. Vet. Sci."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"689","DOI":"10.1055\/s-0030-1269828","article-title":"Pleural Effusions from Congestive Heart Failure","volume":"31","author":"Porcel","year":"2010","journal-title":"Semin. Respir. Crit. Care Med."},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Rae, L., Rand, J., and Ward, L. (2024). Measuring body composition in dogs using bioelectrical impedance spectroscopy. Vet. J., 304.","DOI":"10.1016\/j.tvjl.2024.106067"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"1295","DOI":"10.2460\/ajvr.2001.62.1295","article-title":"Use of dual energy x-ray absorptiometry for noninvasive body composition measurements in clinically normal dogs","volume":"62","author":"Lauten","year":"2001","journal-title":"Am. J. Vet. Res."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"325","DOI":"10.1385\/JCD:4:4:325","article-title":"Dual X-ray absorptiometry assessment of body composition in children with altered body posture","volume":"4","author":"Lark","year":"2001","journal-title":"J. Clin. Densitom."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"65","DOI":"10.1016\/j.tvjl.2016.04.007","article-title":"Measuring body composition in dogs using multifrequency bioelectrical impedance analysis and dual energy X-ray absorptiometry","volume":"212","author":"Rae","year":"2016","journal-title":"Vet. J."}],"container-title":["Animals"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-2615\/15\/19\/2877\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T04:16:36Z","timestamp":1759983396000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-2615\/15\/19\/2877"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,9,30]]},"references-count":46,"journal-issue":{"issue":"19","published-online":{"date-parts":[[2025,10]]}},"alternative-id":["ani15192877"],"URL":"https:\/\/doi.org\/10.3390\/ani15192877","relation":{},"ISSN":["2076-2615"],"issn-type":[{"value":"2076-2615","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,9,30]]}}}