Pyrrole detection and the pathologic progression of Cynoglossum officinale (houndstongue) poisoning in horses.
Abstract: Houndstongue (Cynoglossum officinale), a noxious weed that contains pyrrolizidine alkaloids (PAs), infests pastures and fields in the western United States and Europe. The purpose of this study was to develop techniques to better diagnose PA poisoning and describe the progression of gross and microscopic lesions caused by houndstongue intoxication. Six horses were gavaged daily with a suspension of houndstongue containing 5 or 15 mg/kg total PA for 14 days. Two horses were treated similarly with ground alfalfa as controls. Liver biopsy samples and serum biochemical and hematologic values were evaluated biweekly. Within 7 days after dosing, horses treated with 15 mg/kg PA developed severe liver disease characterized by altered bile acid metabolism, elevated serum enzymes, and extensive hepatocellular necrosis with minimal periportal fibrosis and biliary hyperplasia. The condition of these animals continued to deteriorate, and they were euthanized. For several weeks after dosing, horses treated with 5 mg/kg PA were depressed, had transient elevations of serum enzymes and bile acids, and developed minimal periportal hepatocellular necrosis with fibrosis. The biochemical changes resolved by 6-8 weeks; however, the histologic disease persisted with extensive megalocytosis by week 14. Throughout the study, the rate of hepatocellular proliferation remained constant. Biliary cells had an increase in mitotic rate that correlated with the histologic changes. Hepatic tissue-bound pyrroles (PA metabolites) were identified in necropsy samples of treated animals using gas chromatography/mass spectrometry and photometrically with Ehrlich's reagent. These findings suggest that pyrrole extraction and identification are useful in documenting PA exposure and that houndstongue is extremely toxic to horses.
Publication Date: 1996-01-01 PubMed ID: 9026086DOI: 10.1177/104063879600800113Google Scholar: Lookup
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- Journal Article
Summary
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The research in this article investigates the effects of the houndstongue plant, specifically its pyrrolizidine alkaloids (PAs), on horses and develops methods for diagnosing PA poisoning. The results show that ingestion of this plant, common in western America and Europe, can cause severe liver disease in horses and that identifying pyrrole metabolites can be a useful tool for diagnosing PA poisoning.
Objective and Methodology
- The main goal of this study was to develop diagnostic techniques for PA poisoning in horses and to explore the pathologic progression of the condition induced by houndstongue intoxication.
- In the experiment, six horses were administered a houndstongue suspension containing either 5 or 15 mg/kg total PA, daily for two weeks. Two horses were given ground alfalfa for the same duration as a control group.
- Throughout the study, liver biopsy samples were taken and serum biochemical and hematologic values were evaluated biweekly.
Results and Findings
- Within a week of dosing, the horses administered with the higher concentration of PA (15 mg/kg) developed severe liver disease with symptoms including altered bile acid metabolism, elevated serum enzymes, and widespread hepatocellular necrosis. The animals’ health worsened and they had to be euthanized.
- The horses exposed to a lower concentration of PA (5 mg/kg) showed symptoms of depression, temporary spike in serum enzymes and bile acids, and minor hepatocellular necrosis with fibrosis. The biochemical changes ceased by the sixth and eighth weeks, however, the histologic changes persisted with significantly enlarged cells by the fourteenth week.
- Throughout the experiment, the rate of liver cell proliferation remained consistent. Meanwhile, the mitotic rate or cell division in biliary cells had a noticeable increase pleasingly fitting with the histologic changes.
- Post-mortem examination of the horses revealed the presence of hepatic tissue-bound pyrroles (PA metabolites) in their samples. These pyrroles were detected and assessed using gas chromatography/mass spectrometry and a photometric procedure with Ehrlich’s reagent.
Conclusions
- This research concludes that pyrrole extraction and identification is useful in documenting PA exposure in cases of houndstongue intoxication.
- The study also illuminates the severe toxic effects of houndstongue on horses, particularly the damage it can cause to the liver.
Cite This Article
APA
Stegelmeier BL, Gardner DR, James LF, Molyneux RJ.
(1996).
Pyrrole detection and the pathologic progression of Cynoglossum officinale (houndstongue) poisoning in horses.
J Vet Diagn Invest, 8(1), 81-90.
https://doi.org/10.1177/104063879600800113 Publication
Researcher Affiliations
- USDA Agricultural Research Service, Poisonous Plant Research Laboratory, Logan, UT 84341, USA.
MeSH Terms
- Alkaloids / analysis
- Animals
- Biopsy
- Cecum / pathology
- Colon / blood supply
- Colon / pathology
- Dermatitis / pathology
- Dermatitis / veterinary
- Edema
- Horse Diseases
- Horses
- Infarction
- Liver / pathology
- Necrosis
- Plants, Toxic
- Poisoning / blood
- Poisoning / pathology
- Poisoning / veterinary
- Pyrroles / analysis
Citations
This article has been cited 9 times.- Jager MC, Luethy D, Shallop S, Cathcart J, Divers TJ, Tan JY, Beasley EM, Johnson P, Leduc L, Smith C, Jamieson CA, Magdesian KG, Van de Walle GR, Tomlinson JE. Chronic hepatitis in horses with persistent equine hepacivirus infection. Equine Vet J 2026 Mar;58(2):444-457.
- Stegelmeier BL, David TZ, Panter KE, Welch KD, Knoppel EL. A Review of Intermittent Poisoning to Mitigate Toxic Plant-Induced Disease in Livestock. Vet Sci 2024 Dec 31;12(1).
- Jager MC, Choi E, Tomlinson JE, Van de Walle G. Naturally acquired equine parvovirus-hepatitis is associated with a wide range of hepatic lesions in horses. Vet Pathol 2024 May;61(3):442-452.
- Panter KE, Stegelmeier BL, Gardner DR, Stonecipher CA, Lee ST, Kitchen D, Brackett A, Davis C. Clinical, pathologic, and toxicologic characterization of Salvia reflexa (lance-leaf sage) poisoning in cattle fed contaminated hay. J Vet Diagn Invest 2021 May;33(3):538-547.
- Waizenegger J, Glück J, Henricsson M, Luckert C, Braeuning A, Hessel-Pras S. Pyrrolizidine Alkaloids Disturb Bile Acid Homeostasis in the Human Hepatoma Cell Line HepaRG. Foods 2021 Jan 14;10(1).
- Kolrep F, Numata J, Kneuer C, Preiss-Weigert A, Lahrssen-Wiederholt M, Schrenk D, These A. In vitro biotransformation of pyrrolizidine alkaloids in different species. Part I: Microsomal degradation. Arch Toxicol 2018 Mar;92(3):1089-1097.
- Khordadmehr M, Rezazadeh F, Ashrafi-Helan J, Hosseini-Ghomi MM. The first report of pyrrolizidine alkaloid poisoning in a gazelle (Gazella Subgutturosa) - histopathologic diagnosis. Interdiscip Toxicol 2016 Mar;9(1):30-33.
- Mezzasalma V, Ganopoulos I, Galimberti A, Cornara L, Ferri E, Labra M. Poisonous or non-poisonous plants? DNA-based tools and applications for accurate identification. Int J Legal Med 2017 Jan;131(1):1-19.
- Cortinovis C, Caloni F. Alkaloid-Containing Plants Poisonous to Cattle and Horses in Europe. Toxins (Basel) 2015 Dec 8;7(12):5301-7.
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