Plant induced photosensitvity and dermatitis in livestock

Authors: Stegelmeier, Bryan; Davis, Thomas - Zane; CLAYTON, MICHAEL - Utah State University

Submitted to: Veterinary Clinics of North America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2020
Publication Date: 10/5/2020
Citation: Stegelmeier, B.L., Davis, T.Z., Clayton, M.J. 2020. Plant induced photosensitvity and dermatitis in livestock. Veterinary Clinics of North America. 36:725-733. https://doi.org/10.1016/j.cvfa.2020.08.008.
DOI: https://doi.org/10.1016/j.cvfa.2020.08.008

Interpretive Summary: Whether poisoned by grazing certain toxic plants, by eating contaminated feed, or by topical contact with plant toxins, certain plants poison livestock causing photosensitivity and dermatitis. These dermal lesions are rarely fatal, and with appropriate therapy and protection from additional exposure most lesions heal with few permanent sequelae. However, these lesions often result in costly production losses and missed opportunities. Affected animals may prematurely wean babies, stop eating especially if feed is in the sun, and extensive dermatitis may preclude animals from being worked, or it may impair breeding. As dermatitis is a relatively non-specific response that results from many different etiologies, diagnosis can be challenging. Incorporation of field studies, clinical signs, gross and microscopic pathology as well as chemical identification of plants, toxins and metabolites in animal samples are essential to make an accurate diagnosis. The objectives of this review are to briefly introduce toxic plants that result in photosensitivity and dermatitis, review the toxins and pathogenesis of plant induced skin disease and summarize treatments and recommendations to avoid poisoning.

Technical Abstract: Whether poisoned by grazing certain toxic plants, by eating contaminated feed, or by topical contact with plant toxins, certain plants poison livestock causing photosensitivity and dermatitis. These dermal lesions are rarely fatal, and with appropriate therapy and protection from additional exposure most lesions heal with few permanent sequelae. However, these lesions often result in costly production losses and missed opportunities. Affected animals may prematurely wean babies, stop eating especially if feed is in the sun, and extensive dermatitis may preclude animals from being worked, or it may impair breeding. As dermatitis is a relatively non-specific response that results from many different etiologies, diagnosis can be challenging. Incorporation of field studies, clinical signs, gross and microscopic pathology as well as chemical identification of plants, toxins and metabolites in animal samples are essential to make an accurate diagnosis. The objectives of this review are to briefly introduce toxic plants that result in photosensitivity and dermatitis, review the toxins and pathogenesis of plant induced skin disease and summarize treatments and recommendations to avoid poisoning.