NEUTROPHILS WITH RING NUCLEAR CHANGES IN DOGS AND CATS TREATED AT THE VETERINARY HOSPITAL OF THE FEDERAL UNIVERSITY OF PARANÁ – PALOTINA SECTOR: FREQUENCY AND ASSOCIATION WITH HEMATOLOGICAL CHANGES AND CLINICAL OUTCOME

Abstract

The morphological evaluation of leukocytes in blood smears is an essential tool for the diagnosis and monitoring of inflammatory processes in veterinary medicine. Neutrophils with ring-shaped nuclei (donut cells) represent an atypical morphological alteration associated with granulocytic maturation dysfunctions, described in myeloproliferative and infectious diseases in humans, but scarcely studied in dogs and cats. This retrospective study evaluated 25 patients, 14 dogs and 11 cats, treated at the Veterinary Hospital of the Federal University of Paraná, Palotina Campus, between March 2024 and August 2025, who presented neutrophils with ring-shaped nuclei. Demographic data, clinical diagnoses, leukograms, and clinical outcomes were collected from these patients. A constant presence of left shift and neutrophilic toxicity was observed, even in patients with total leukocyte counts within the reference range, highlighting the importance of morphological analysis for a more accurate diagnosis. Pyometra and viral diseases were the most frequent diagnoses in dogs and cats, respectively, with high mortality associated with the presence of these cells. The results suggest that neutrophils with ring-shaped nuclei reflect an intense bone marrow response to severe inflammatory stimuli, reinforcing their relevance as a clinical and prognostic indicator. The identification of these cells should be incorporated into routine veterinary diagnostics to improve patient management.