Description of Acute and Chronic Cases of Poisoning by Oxalis pes-caprae.

Oxalis pes-caprae is one of the most widespread invasive plants in the Mediterranean areas, especially in central and southern Italy, Sicily, and Sardinia. It is an herbaceous species of South African origin, very common in uncultivated areas, in meadows, and at the edges of roads but also in vegetable gardens and fields, where it can become a weed. Its negative impact on the economic sector is significant due to the presence of large quantities of oxalates, which are toxic and dangerous for grazing livestock; the ingestion of high amounts of oxalates causes the accumulation of oxalate crystals, which can lead to kidney failure and anuria. This work represents a descriptive, field-based case report of epidemiological relevance, describing two cases of acute and chronic poisoning by Oxalis pes-caprae found in two different sheep farms in southern Sardinia. In February 2024, the sudden death of about 40 animals was reported in a sheep farm. On another farm, seven animals died (between March and July 2024), while others showed poisoning symptoms such as weight loss, submandibular edema, and a barrel-shaped abdomen. This manuscript aims to highlight the damage caused by poor attention in pasture management and the importance of seasonal risk management; it is necessary to pay attention to the herbaceous species present in pastures, especially in our region, where climatic temperatures no longer respect seasonality and herbaceous species that normally grow in spring are easily found also in the winter months.