What High-Dose Oral THC Toxicity in Sheep Can—and Cannot—Show
High-dose THC caused substantial adverse effects in sheep, but the experiment does not establish a toxic human dose or a human impairment threshold. Veterinary toxicology findings need to remain attached to the species, administration schedule, and measured outcomes.
The exposure was specific and substantial
Stevens and colleagues described eight Merino ewes given two oral doses of THC, each 88.5 mg/kg, 12 hours apart. The investigation arose within research on hemp biomass as a potential ruminant feed and a broader pharmacokinetic project.
This was controlled animal exposure, not observation of humans consuming ordinary cannabis products. The administered mass per body weight should not be converted directly into a recommended or toxic human dose.
Clinical signs and a separate cardiac marker
Observed signs included ataxia, abnormal posture, somnolence, increased salivation, and prolonged reduction in feeding with loss of body weight. Plasma troponin I increased in three of the eight sheep. Behavioral observations and a plasma cardiac marker are different endpoints, each requiring its own interpretation.
Troponin is not a measurement of blood THC, and its elevation does not quantify the degree of intoxication. Similarly, seeing ataxia after experimental administration does not make ataxia specific to THC in a different clinical case.
Why the study does not define a universal boundary
The sample was small, involved a single species and sex, and used a particular repeated high-dose regimen. Ruminant physiology, exposure formulation, and feeding conditions limit translation. The paper discusses possible implications for hemp feeding, but the experiment does not map a complete dose-response curve for every hemp preparation or animal population.
The pharmacokinetic findings were reported separately; they should not be invented from the clinical-sign descriptions in this paper.
How to evaluate an extrapolation
Ask whether the opinion concerns animal feed safety, an actual veterinary exposure, or a human case. Compare the dose, route, interval, product composition, and clinical findings. Identify which findings were directly observed rather than inferred from other cited studies.
The research supports concern about adverse effects under the tested conditions. It does not establish that any cannabinoid-positive human specimen represents equivalent exposure or proves the cause of an individual’s neurological or cardiac findings.
Related evidence
For the distinction between detecting cannabis and establishing its significance, see our analysis of exposure, impairment, and crash-risk evidence.
Primary research
The toxicology of orally administered Δ9-tetrahydrocannabinol in sheep. Toxicology Reports, 2026. DOI: 10.1016/j.toxrep.2026.102221.
