How Much THC Reaches Circulation From a CBD-Dominant Oil? Evidence From Beagles
A CBD-dominant hemp oil produced measurable THC exposure in dogs, and its oral availability differed from CBD’s. The product’s dominant cannabinoid does not fully describe the exposure to its other constituents.
Comparing oral and intravenous administration
Kitts-Morgan and colleagues studied six adult beagles receiving the same full-spectrum formulation intravenously, orally, and repeatedly by mouth. Serum was analyzed for CBD, THC, and several oxidative metabolites. Comparing routes in the same animals allowed estimation of systemic availability.
The oral formulation was administered with food. Results from this product and feeding condition cannot automatically be assigned to all hemp oils or to fasting animals.
Absorption is not identical to systemic availability
The reported median oral availability was approximately 31% for CBD and 41% for THC. Substantial first-pass metabolism helps explain why drug entering the gastrointestinal tract does not all reach systemic circulation as unchanged parent compound.
The formulation was well tolerated during the study. Alkaline phosphatase increased during repeated dosing but remained within the reference range. A laboratory change, an out-of-range result, and clinically demonstrated liver injury are different findings.
What this means for interpretation
The study lacked a placebo group and included few young, purpose-bred dogs. Its short repeated-dosing period cannot exclude uncommon or delayed effects, and the results do not provide a human dose conversion.
A statement that a product is “mostly CBD” is not evidence of zero THC exposure. Interpretation should identify the product composition, administered amount, food conditions, matrix, and measured analytes. The serum pharmacokinetics establish exposure in this animal model; they do not establish a human impairment threshold or safety of every full-spectrum product.
The availability estimates also varied between individual dogs: approximately 18–36% for CBD and 21–46% for THC after the single oral dose. Reporting only the median conceals that spread. Even within this small, controlled animal experiment, the proportion reaching systemic circulation was not one invariant percentage for every subject.
Related reading: physiological findings after cannabis oils in dogs.
Primary research
Susanna E. Kitts-Morgan; Richard A. Sams; William W. Muir. Pharmacokinetics of cannabidiol, (-)-trans-Δ9-tetrahydrocannabinol, and their oxidative metabolites after intravenous and oral administration of a cannabidiol-dominant full-spectrum hemp product to beagle dogs. Frontiers in Veterinary Science (2025). DOI: 10.3389/fvets.2025.1556975.
