animals Article Endometrial Status in Queens Evaluated by Histopathology Findings and Two Cytological Techniques: Low-Volume Uterine Lavage and Uterine Swabbing Alba Martí 1 , Anna Serrano 1 , Josep Pastor 1, *, Teresa Rigau 1 , Ugné Petkeviˇ ciuté 1 , Maria Àngels Calvo 2 , Esteban Leonardo Arosemena 2 , Aida Yuste 2 , David Prandi 1 , Adrià Aguilar 1 and Maria Montserrat Rivera del Alamo 1   Citation: Martí, A.; Serrano, A.; Pastor, J.; Rigau, T.; Petkeviˇ ciuté, U.; Calvo, M.À.; Arosemena, E.L.; Yuste, A.; Prandi, D.; Aguilar, A.; et al. Endometrial Status in Queens Evaluated by Histopathology Findings and Two Cytological Techniques: Low-Volume Uterine Lavage and Uterine Swabbing. Animals 2021, 11, 88. https:// doi.org/10.3390/ani11010088 Received: 4 December 2020 Accepted: 30 December 2020 Published: 5 January 2021 Publisher’s Note: MDPI stays neu- tral with regard to jurisdictional clai- ms in published maps and institutio- nal affiliations. Copyright: © 2021 by the authors. Li- censee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and con- ditions of the Creative Commons At- tribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Department of Animal Medicine and Surgery, Veterinary School, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain; g21alba@gmail.com (A.M.); anna95serrano@gmail.com (A.S.); teresa.rigau@uab.cat (T.R.); petkeviciute.ugne23@gmail.com (U.P.); david.prandi@uab.cat (D.P.); adria.aguilar@uab.cat (A.A.); mariamontserrat.rivera@uab.cat (M.M.R.d.A.) 2 Department of Anatomy, Veterinary School, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain; mariangels.calvo@uab.cat (M.À.C.); estebanleonardo.arosamena@uab.cat (E.L.A.); aidayuste@gmail.com (A.Y.) * Correspondence: josep.pastor@uab.cat; Tel.: +34-581-3445 Simple Summary: The endometrium health of feline queens can be difficult to assess due to the reduced size of the uterus, which hinders representative biopsy sampling. This may result in limitations in diagnosing endometritis, and consequently in detecting infertility problems. Although histology is considered the most reliable technique for diagnosing endometritis in many species, cytology is also gaining importance and may be an alternative tool for evaluating the endometrium in small species. Two different common cytological techniques (uterine lavage and uterine swabbing) were compared to determine the reliability of cytology for evaluating the endometrium status in queens. Histopathological and bacteriological information was used for the control methods. Our results demonstrated that cytology may be a useful diagnostic tool for assessing the endometrial status. In addition, when comparing cytological techniques, the uterine lavage method was more representative than uterine swabbing. Abstract: Endometritis is associated with fertility problems in many species, with endometrial biopsy being the main diagnostic tool. In feline queens, the reduced size of the uterus may make it difficult to obtain representative diagnostic samples. Endometrial cytology may represent a valuable diagnostic tool for evaluating the health status of the endometrium in queens. Fifty domestic shorthair queens were included and divided into two cytological diagnostic technique groups, the uterine lavage (UL; n = 28) and uterine swabbing (US; n = 22) groups. Cytological results were compared with histopathological and bacteriological information. Changes in the histopathological patterns were also evaluated and compared with progesterone levels to confirm previous published data. Furthermore, the results from both cytological sampling methods were compared to evaluate the utility of each method. Endometritis was ruled out in all queens by means of histology and microbiology. Leukocyte counts and red blood cell/endometrial cell ratios were significantly higher in US than UL samples. Additionally, UL sampling is less affected by blood contamination and cells are better preserved. The combination of endometrial cytology and uterine culture might be useful for evaluating the endometrial characteristics in queens. The UL evaluation method is more representative of the actual endometrial status than the US technique. Keywords: uterus; cytology; polymorphonuclear neutrophil; queen Animals 2021, 11, 88. https://doi.org/10.3390/ani11010088 https://www.mdpi.com/journal/animals