Peer-reviewed veterinary case report
Severe urticaria in a horse after consumption of horseweed (Conyza canadensis (L.) Cronquist) - A case study.
- Journal:
- Acta veterinaria Hungarica
- Year:
- 2025
- Authors:
- Cserhalmi, Dániel & Wermer, Kata
- Affiliation:
- University of Veterinary Medicine
- Species:
- horse
Plain-English summary
This case study discusses a Welsh pony mare that developed severe hives after eating horseweed, a type of plant. The pony showed signs like swollen eyes, low energy, and widespread hives on her skin. A thorough examination didn't show any other health issues, and tests confirmed that horseweed was the main plant she had been eating, which can cause allergic reactions in some horses. This study is significant because it provides new insights into how horseweed can affect horses, particularly in causing allergic reactions. The treatment for the pony's condition was successful in addressing her symptoms.
Abstract
Our paper presents a case study of a Welsh pony mare with grazing-induced severe urticaria. The main clinical signs were eye swelling, depression and extensive urticaria. Physical examination revealed no other abnormalities. Botanical sampling revealed horseweed (Conyza canadensis) as the most abundant species and a potential allergen plant due to sesquiterpene lactones (SQL). Differential diagnosis strongly suggested that the clinical signs were the result of a hypersensitivity reaction to this plant. Former studies brought controversial data about the toxic or allergic potential of horseweed especially for equids thus our paper is the first interpretation of horseweed induced urticaria.
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Search related cases →Original publication: https://pubmed.ncbi.nlm.nih.gov/40471695/