Vetnews | Maart 2026 22 « BACK TO CONTENTS In an attempt to elucidate the origin of the leukaemia, corroborating the patient’s exposure to glyphosate, whole blood was collected in a heparin tube for the comet assay (HALDER et al., 2002). For the comet assay (Figure 2), the results indicate moderate damage (x±SD), as observed across all parameters, such as Tail Length (10.06±7.14), Olive Tail Moment (2.25±2.01), and %DNA in the tail (21.51±15.36). In this regard, in at least one of the parameters, the mean was consistent with other studies that demonstrated significant DNA damage due to pesticide exposure (HONG et al., 2017; KWIATKOWSKA et al., 2017; LOPES et al., 2021). Furthermore, DNA fragmentation may also indicate cytotoxic potential, as previously described (ESCOBAR et al., 2007). Other studies also highlight the genotoxicity attributed to herbicides in dogs. Both glyphosate and 2,4-D were genotoxic to canine cells at concentrations of 0.10 μM and above (TINDLE et al., 2025). Glyphosate exposure, as previously stated, may be cancerous, particularly regarding the surfactants used in the current formulation of the product (GASNIER et al., 2009). Its full toxic potential, especially regarding cancer presentations (CHANG; DELZELL, 2016; DAVOREN; SCHIESTL, 2018), is yet to be established in both humans and animals. The dog reported in the present document was young, with no previous conditions and a recent exposure to a supposedly large amount of glyphosate in its environment. Both haematology and myelogram support the diagnosis of leukaemia, and the comet assay further suggests a toxic agent as a possible factor in the cancer development. Among herbicides, glyphosate has been reported as the main culprit in poisoning cases involving domestic animals such as dogs, cats, horses, goats, and sheep (CALONI et al., 2016). However, acknowledging some limitations of this study, it is important to highlight the financial constraints that prevented additional investigations using flow cytometry and immunocytochemistry to determine the cellular origin. Furthermore, chemotherapy was recommended; however, the treatment was not carried out for personal reasons, and the patient died five days after the consultation. Necropsy was not authorised. Further toxicological analysis from serum samples was attempted, but was not successful due to the difficulty in glyphosate detection and the lack of specialised services in Brazil. Considering the susceptibility of domestic animals to contact with pesticides and other xenobiotics, this study highlights the risks of intoxication. Exposure to household xenobiotics may occur through oral ingestion or inhalation, although some pesticides are not volatile due to their molecular weight. However, inhalation of glyphosate surfactant herbicide by a dog has been documented, resulting in hypersalivation, tremors, and hyperthermia, followed by death (CORTINOVIS et al., 2015). In the present study, it was not possible to determine the route and duration of exposure. Finally, environmental contamination by household chemicals represents a global challenge, and bioindicators such as pets can be essential tools for effective monitoring and risk assessment (BERTERO et al., 2020). Conclusion In this study, we report a case of suspected glyphosate poisoning in a dog. Although the data indicate a severe acute response of leukaemia and DNA damage, further studies are still needed in the future. The findings contribute to the understanding of glyphosate poisoning and its consequences in canines. This case reinforces the importance of implementing biosecurity measures in rural areas and training veterinarians to recognise early signs of pesticide poisoning in domestic animals. v Figure 1. Microscopic evaluation of cells from a dog suspected of glyphosate poisoning. A) Photomicrograph of blood smear of intense cellularity composed of 95% of blasts of unidentified origin and 5% of segmented neutrophils. 100x. B) Cytological sample of moderate cellularity, with predominance of primitive cells of undetermined origin Figure 2. Photomicrograph of the Comet Assay showing one normal nucleoid and another fragmented in a dog suspected of glyphosate poisoning. Article References available on request Email: assistant@sava.co.za ADVERTISE IN VETNEWS MAGAZINE
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