Abstract
OBJECTIVE: To assess the usefulness of rectal temperature responses in Australian bred Merino sheep, following the oral administration of Hypericum perforatum (St John's wort), as an early indicator of Hypericum intolerance. DESIGN: Thirty-three Merino ewes were divided into three groups of 11. Each group was dosed with finely ground, dried, flowering growth stage H perforatum plant material at either 5.7, 4.0, or 2.85 g dry plant per kg live weight. This corresponded to 5.3, 3.7 and 2.65 mg hypericin per kg live weight, respectively. PROCEDURE: The sheep were dosed with a plant slurry by stomach tube and then exposed to bright sunlight for up to 5 h per day over successive days. Their clinical responses were observed and rectal temperature measured. RESULTS: Ingestion of H perforatum followed by exposure to bright sunlight frequently resulted in clinical signs attributable to skin irritation and central nervous effects, including an inappropriate increase in body temperature. A decrease in H perforatum ingestion from 5.7 to 2.85 g dry plant per kg live weight and a corresponding decrease in hypericin ingestion from 5.3 to 2.65 mg per kg live weight, was associated with a decrease in the severity of the clinical signs, including the severity of the hyperthermia. CONCLUSIONS: The rectal temperature rise in affected sheep is a reliable indicator of the early development of an adverse clinical effect. There appears to be an absolute requirement for exposure to bright sunlight before any effects of H perforatum will develop. A single dose of H perforatum remains potentially effective for up to 4 days. In the small group of Merino sheep tested a tolerance level for H perforatum, eaten at the flowering stage, of < 1% (plant wet weight) of body weight and a tolerance level for hypericin of < 2.65 mg per kg live weight, were demonstrated.
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Claims 7
Claim · model-written summary
Hypericum perforatum ingestion followed by bright sunlight exposure caused clinical signs including an inappropriate increase in body temperature in sheep.
- Taxon
- Hypericum perforatum
_Hypericum_perforatum_flower_and_buttons.jpg?width=60)
Hypericum perforatumt0 - Treatment
- Ingestion of H perforatum followed by exposure to bright sunlighte1
- Interactor
- sheep
Ovis ariest0herbivore - Outcome
- body temperaturee1
- Direction
- increasee1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_Hypericum_perforatum_flower_and_buttons.jpg?width=500)
Verbatim
t0“sheep intoxicated by St John's wort (Hypericum perforatum)”
e1“Ingestion of H perforatum followed by exposure to bright sunlight frequently resulted in clinical signs attributable to skin irritation and central nervous effects, including an inappropriate increase in body temperature”
Claim · model-written summary
A decrease in H perforatum intake from 5.7 to 2.85 g dry plant per kg live weight was associated with reduced severity of clinical signs.
- Taxon
- H perforatumHypericum perforatume2
- Treatment
- H perforatum ingestione2
- Outcome
- severity of the clinical signse3
- Direction
- decreasee3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“A decrease in H perforatum ingestion from 5.7 to 2.85 g dry plant per kg live weight”
e3“was associated with a decrease in the severity of the clinical signs”
Claim · model-written summary
Exposure to bright sunlight appears to be an absolute requirement before H perforatum effects develop.
- Taxon
- H perforatumHypericum perforatume4
- Treatment
- exposure to bright sunlighte4
- Outcome
- any effects of H perforatume4
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e4“There appears to be an absolute requirement for exposure to bright sunlight before any effects of H perforatum will develop”
Claim · model-written summary
A single dose of H perforatum remains potentially effective for up to 4 days.
- Taxon
- H perforatumHypericum perforatume5
- Treatment
- A single dose of H perforatume5
- Outcome
- potentially effectivee5
- Value
- up to 4 dayse5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“A single dose of H perforatum remains potentially effective for up to 4 days”
Claim · model-written summary
The tolerance level for H perforatum eaten at the flowering stage was below 1% of body weight (plant wet weight) in the small Merino group tested.
- Taxon
- H perforatumHypericum perforatume6
- Organ / stage
- flowering stagee6
- Outcome
- tolerance levele6
- Value
- < 1% (plant wet weight) of body weighte6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“a tolerance level for H perforatum, eaten at the flowering stage, of < 1% (plant wet weight) of body weight”
Claim · model-written summary
The tolerance level for hypericin was below 2.65 mg per kg live weight in the small Merino group tested.
- Taxon
- Hypericum perforatumHypericum perforatumt0
- Compound
- hypericine7
- Outcome
- tolerance levele7
- Value
- < 2.65 mg per kg live weighte7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“sheep intoxicated by St John's wort (Hypericum perforatum)”
e7“a tolerance level for hypericin of < 2.65 mg per kg live weight”
Claim · model-written summary
The rectal temperature rise in affected sheep is a reliable indicator of the early development of an adverse clinical effect.
- Taxon
- sheepOvis ariese7
- Outcome
- rectal temperature risee7
- Qualifier
- reliable indicator of the early development of an adverse clinical effecte7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e7“The rectal temperature rise in affected sheep is a reliable indicator of the early development of an adverse clinical effect”