Case of Eagle Fern (Pteridium Aquilinum) Poisoning on a Pig Farm

Abstract

Background: Free-range pig farming represents a minor proportion of pig production in France but attracts an increasing number of farmers because of societal expectations and the opportunity to use fodder consumed in the meadow. However, this type of farming faces several sanitary challenges, including biosecurity, parasitic management, and contact with wild fauna and pathogenic flora. Case presentation: Two Gascon pigs raised on an outdoor fattening farm in the Hautes-Pyrenees department of France were submitted after sudden death for necropsy at the National Veterinary School of Toulouse. The pigs were of two different breeds but from the same batch of 85 animals that had grazed on a 4-hectare plot of land being used for the first time. The combination of an in-depth interview with the breeder, the epidemiological information available, and the necropsy and histology examinations enabled the hypothesis of great eagle fern intoxication. Despite the small sample of animals available for diagnosis, the success of the administered therapy helped to confirm our diagnosis. In the short term, it was recommended that the animals be prevented access to the eagle fern by changing their pasture or by removing the plants. Vitamin B1 was administered in the feed in the amount of 1 mL per 10 kg body weight for two days (Ultra B®: 4.46 mg thiamine and 2.06 mg pyridoxine (vitamin B6) per kg body weight per day). A remarkable remission was observed, allowing 6 of 12 intoxicated animals with symptoms to survive (therapeutic success rate: 50%), but without compensating for the loss of the initial body condition. In total, out of the 85 animals in the batch after this intoxication, 6 animals died and 6 recovered.Conclusion: The interest of this report lies in the scarcity of eagle fern intoxication cases reported in the literature, although it may become a significant problem along with the development of outdoor rearing. In this context, it should be included in the differential diagnosis of nervous system symptoms in swine. The case also underlines the importance of anamnesis and discussions with the farmer to guide the diagnosis and reminds us that this step is essential in the clinical process.