Large-scale epidemiological and diagnostic assessment of canine cytology in Portugal: insights from 12,671 retrospective cases

Vet World Vol.18 October-2025 Article - 3

Research Article

Veterinary World, 18(10): 2955-2968

https://doi.org/10.14202/vetworld.2025.2955-2968

Paula Brilhante-Simões^1,2,3, Ricardo Lopes^4,3, Leonor Delgado^1,4,5, Ana Machado^1,6, Augusto Silva¹, Carla Gomes⁷, Ângela Martins⁸, Ricardo Marcos^9,10, Felisbina Queiroga^6,8,11, and Justina Prada^6,8,11

1. INNO Veterinary Laboratories, R. Cândido de Sousa 15, 4710–300 Braga, Portugal.

2. Department of Veterinary and Animal Sciences, University Institute of Health Sciences (IUCS), Polytechnic and University Higher Education Cooperative (CESPU), 4585-116, Gandra, Portugal.

3. Department of Veterinary Sciences, University of Trás–os–Montes e Alto Douro (UTAD), 5000-801, Vila Real, Portugal.

4. Department of Veterinary and Animal Sciences, University Institute of Health Sciences (IUCS), Polytechnic and University Higher Education Cooperative (CESPU), 4585-116, Gandra, Portugal.

5. UNIPRO-Oral Pathology and Rehabilitation Research Unit, University Institute of Health Sciences- Polytechnic and University Higher Education Cooperative (CESPU), 4585-116, Gandra.

6. Department of Veterinary Sciences, University of Trás–os–Montes e Alto Douro (UTAD), 5000-801, Vila Real, Portugal.

7. Animal Health Ireland, 2-5 The Archways, Carrick-on-Shannon, Co. Leitrim N41 WN27, Republic of Ireland.

8. Animal and Veterinary Research Centre (CECAV), Associate Laboratory for Animal and Veterinary Sciences (AL4AnimalS), University of Trás-os-Montes e Alto Douro (UTAD), 5000-801, Vila Real, Portugal.

9. Cytology and Hematology Diagnostic Services, Laboratory of Histology and Embryology, Department of Microscopy, ICBAS-School of Medicine and Biomedical Sciences, University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313, Porto, Portugal.

10. Animal Morphology and Toxicology Team (CIIMAR). Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Matosinhos, Portugal.

11. Center for the Study of Animal Sciences of the Institute of Sciences, Technologies and Agro-Environment of the University of Porto, CECA-ICETA, University of Porto, 4200-465, Porto, Portugal.

Background and Aim: Cytology is a minimally invasive, rapid, and cost-effective diagnostic tool widely used in veterinary medicine for evaluating a broad range of lesions. While extensively applied in clinical practice, large-scale epidemiological analyses of cytologic findings in canine populations are limited. This study aimed to evaluate the diagnostic performance of cytology in dogs in Portugal, assessing associations between lesion type, anatomical location, and demographic factors, and to identify patterns that can improve diagnostic utility in veterinary practice.

Materials and Methods: A retrospective analysis was conducted on 12,671 cytological samples collected from canine patients between January 2010 and December 2016, submitted by 355 veterinary practices across mainland Portugal. Samples were categorized by anatomical location and diagnostic classification (neoplastic, inflammatory, non-neoplastic/non-inflammatory, and other). Demographic variables (sex, age, and breed) were recorded. Statistical analyses included non-parametric tests, logistic regression, and trend analyses to explore associations between diagnostic outcomes and study variables.

Results: The overall diagnostic yield was 69.03%, with the highest rates in fluid (80.21%), mucosal (77.08%), and glandular (75.78%) samples. Cutaneous/subcutaneous lesions, although the most frequent, had the lowest diagnostic yield (66.12%). Of diagnostic cases, 43.94% were neoplastic, with prevalence increasing significantly with age, from 17.75% in dogs ≤1 year to 54.75% in those >10–15 years (p < 0.001). Females were more likely to present epithelial and mesenchymal lesions, while males more frequently had round cell and melanocytic lesions. Breed analysis revealed no significant predispositions after statistical adjustment. Veterinary hospitals achieved higher diagnostic rates than clinics (p = 0.002). Non-diagnostic samples (30.97%) were primarily attributed to poor sample quality or insufficient cellularity.

Conclusion: Cytology is a valuable first-line diagnostic modality in canine veterinary practice, particularly effective for fluid, mucosal, and glandular lesions. Lesion prevalence varies significantly with age and sex, highlighting the need for tailored diagnostic considerations. Standardizing sample collection and preparation techniques, especially for anatomical sites with lower yields, could further improve diagnostic accuracy. While the absence of histopathological confirmation limits definitive classification, the large dataset and standardized diagnostic review strengthen the reliability of findings. Integrating cytology into routine diagnostics can enhance early disease detection, guide treatment decisions, and support epidemiological surveillance.

Keywords: canine cytology, diagnostic yield, epidemiology, neoplasia, retrospective study, veterinary diagnostics.

How to cite this article: Brilhante-Simões P, Lopes R, Delgado L, Machado A, Silva A, Gomes C, Martins Â, Marcos R, Queiroga F, and Prada J (2025) Large-scale epidemiological and diagnostic assessment of canine cytology in Portugal: insights from 12,671 retrospective cases, Veterinary World, 18(10): 2955-2968.

Received: 19-03-2025 Accepted: 29-08-2025 Published online: 08-10-2025

Corresponding author: Felisbina Queiroga E-mail: Felisbina Queiroga

DOI: 10.14202/vetworld.2025.2955-2968

Copyright: fqueirog@gmail.com, et al. This article is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.