Vetnuus | March 2026 21 Material and Methods Case study A seven-month-old, 10.2 kg male, mixed breed canine, was referred to the Veterinary Hospital of the Federal University of Goiás, presenting mental confusion and imbalance. During the anamnesis, the guardian reported changes in consciousness plus uncoordinated head and hind limb movements. It was also reported hyporexia and normodipsia, with no history of diarrhoea, fainting, epileptic seizures, trauma, or previous illnesses. The patient lived in a rural environment, and when asked about access to toxic products, it was reported that twelve days before the consultation, they had used the product Roundup® in the grass of the farm to kill weeds. The animal had access to the grass area and the street and was fed only homemade food. Clinical exams A depressed state of consciousness and reactive superficial mandibular and cervical lymph nodes were observed on physical examination. Mucosal staining, capillary filling time, skin turgor, temperature, and cardiac and pulmonary auscultation were normal. The neurological examination revealed a reduced response to threat in both eyes, preserved facial sensitivity, normal to reduced swallowing and jaw tone, and preserved withdrawal reflex and superficial pain in the four limbs. When assessing the patient in motion, proprioceptive ataxia, broad-based station, and head tremors when moving around were observed. Based on history, anamnesis, and clinical signs, some infectious diseases, such as distemper, ehrlichiosis, toxoplasmosis, leishmaniasis, and herbicide poisoning, were suspected. To better understand this case, a rapid test for distemper (Alere®), Complete blood count (CBC), search for Lentz corpuscles, creatinine, and alanine aminotransferase (ALT) were requested. Comet Assay The comet assay was performed on peripheral blood as a biomarker of genotoxicity. The alkaline assay was based on Singh et al. (1988), with some modifications (RAMOS et al., 2021). A total of 15 μL of blood was homogenised in 120 μL of low- melting-point agarose. This sample was placed on slides, and after solidification, the slides were immersed in a cold lysis buffer in a light-protected chamber, where they remained for 15 hours. After this period, the slides were removed from the lysis solution and placed in a horizontal electrophoresis tank, where they were incubated in an alkaline buffer at 4°C for 30 minutes. Electrophoresis was then performed for 30 minutes at 25 volts and 250 mA, maintaining a temperature of 4°C. The slides were neutralised using a Tris solution, repeated three times at 5-minute intervals. After neutralisation, the slides were washed with distilled water and then fixed by immersion in absolute ethanol for 10 minutes. Once dried, the DNA was stained with 100 μL of SYBR® Green I solution. A total of 100 cells per slide (two slides in total) were analysed using an Axio Imager D2® fluorescence microscope (Carl Zeiss, Berlin, Germany) by a single observer, using a 20x objective. Three genomic damage parameters were assessed: tail length, percentage of DNA in the tail, and Olive tail moment. Data Analysis The data from this case are presented in absolute and relative frequencies, as well as compared to findings from other studies analysing the same parameters/biomarkers. Furthermore, for the Comet Assay, the data are presented as mean ± standard deviation (SD). Results and Discussion This study highlights a fatal case of suspected glyphosate poisoning in a dog. The rapid test result was negative, and the CBC showed normocytic normochromic anaemia, packed cell volume (PCV) of 20%, with the slight presence of codocytes and thrombocytopenia (50.000/µl). Anaemia is characterised by a reduction in red blood cells or in the blood’s ability to transport oxygen, due to decreased packed cell volume, red blood cell count, or haemoglobin concentration below reference values (PADALINO et al., 2016). In this context, some studies indicate an association between anaemia and exposure to pesticides (YUSHANANTA et al., 2020; ASIF SYED et al., 2021). It was also possible to observe intense leukocytosis (447.200/ µl), composed of 95% of blasts of unidentified origin and 5% of segmented neutrophils. The observed blasts showed mild to moderate anisocytosis and pleomorphism, mild to moderately basophilic cytoplasm, and mild to moderate vacuolization in all cells. Its nucleus/cytoplasm ratio varied from mild to moderate; the nuclei had moderate anisocariosis, moderate pleomorphism (round, oval, and monocytoid), possible figures of aberrant mitosis, and rare binucleations. The nucleoli, possibly prominent, rounded, or angular nucleoli, were observed, sometimes multiple, with discrete anisonucleolysis. Rare lymphoglandular corpuscles were present, mild to moderate cell fragility and recurrent cell apoptosis (Figure 1). Based on the patient’s history and complementary exams, leukemia was investigated. Leukemia is a clonal proliferation of hematopoietic stem cells in the bone marrow (DAVIS et al., 2014). Thus, for further clarification, the patient was directed to perform the myelogram. Optical microscopy showed a moderately cellular sample, with a high predominance (more than 95%) of primitive cells of undetermined origin isolated in cell islands. Cellular characteristics included mild to moderate anisocytosis, high to medium nucleus/cytoplasm ratio, and intense cytoplasmic and nuclear basophilia. There was intense cellular fragility and rare lymphoglandular corpuscles; some cells had a morphology similar to “hand mirror.” Rare myeloid precursors and possible mature neutrophils, very few erythroid precursors, and no megakaryocytic precursors were observed (Figure 1). Such findings indicated an exacerbated proliferation of the blast population with a break in the expected proportionality of the medullary compartments, confirming the suspicion of leukemia. Leukemia is a complex neoplasia that is often associated with previous exposure to toxic components such as benzene (SNYDER, 2012). Acute myeloid leukemia is a rare and progressive cancer in dogs. Recent studies revealed that diagnosis can be based on more than 20% blasts in bone marrow, as described in the present report (DAVIS et al., 2018). The most common clinical signs are inappetence, lethargy, and lymphadenopathy, and clinical pathology findings suggest an increase in blast circulation, anemia, and thrombocytopenia, also corroborating our findings. The mean survival time was 19 days, ranging from 1 to 121 days. Article >>>22
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