Cannabinoids in Companion Animals: Clinical Notes for Veterinary Teams
These are the clinical notes for the 1-hour continuing education lecture “CBD for Pets,” presented by Dr. Terry Fossum for the Dr. Fossum’s Pet Care veterinary CE series.
They are written for veterinarians and veterinary technicians: the endocannabinoid pharmacology, the published veterinary trials, what each one measured and where each one is thin, the product-quality questions clients cannot evaluate alone, and the regulatory requirements that decide what any of us may say out loud. The lecture was recorded in 2020; a dated what-has-changed section keeps the volatile facts current.
Clinical bottom line
Clients ask about hemp-derived CBD, and the profession is not uniformly ready: in the 2019 VIN survey of 2,130 US veterinarians, 61.5 percent were comfortable discussing it with colleagues and 45.5 percent with clients.
The veterinary literature the lecture reviews is four small, short studies (two controlled canine trials, one open-label pilot and one healthy-animal tolerance study that includes cats); what repeats across them is pharmacologic, not clinical: alkaline phosphatase rises in a share of dogs, cats absorb or eliminate oral CBD differently from dogs, and CBD shares cytochrome P450 metabolism with much of the formulary.
Product quality is the exam-room problem you can actually solve: 69 percent of 84 online CBD products were mislabeled in a 2017 JAMA analysis, and only 10 of 27 labeled veterinary hemp products were within 10 percent of their stated cannabinoid content in a 2020 Cornell analysis, so certificate-of-analysis literacy is the most useful thing a veterinary team can teach a client.
Legally, Epidiolex is the only FDA-approved CBD drug (human), no cannabinoid product is approved for animals, and disease claims for any other CBD product are off-limits for everyone, including us; a veterinarian’s extralabel use of the approved human drug is a separate question under AMDUCA and state law.
About the lecturer
Terry W. Fossum, DVM, MS, PhD, DACVS is a board-certified veterinary surgeon and the author of Small Animal Surgery, a standard surgical textbook of the profession. Disclosure, made in the lecture’s opening minutes and repeated here: Dr. Fossum is the CEO and co-founder of Dr. Fossum’s Pet Care, which sponsors this CE program and sells hemp-derived products; the lecture’s product segment is deliberately not part of these educational notes.
Where the profession stands (1:00)
The lecture opens with the 2019 VIN survey of 2,130 US veterinarians (Kogan 2019): 61.5 percent felt comfortable discussing CBD with colleagues, 45.5 percent with clients. Comfort did not differ by state law; behavior did: veterinarians in states with legal recreational marijuana were more likely to talk with clients about CBD and to recommend it.
Two findings worth remembering in practice: recent graduates were less comfortable discussing CBD than their more experienced colleagues, and participants felt their state associations and boards had not given them enough guidance to practice within the law. Whether both still hold in 2026 is untested; in practice, client demand still runs ahead of institutional guidance.
The survey also asked what respondents discussed CBD for (pain, anxiety and seizures were the most common answers) and what they saw go wrong (sedation was the most commonly reported side effect). Those are perceptions, not outcomes; the studies below are where the measurements are.
Definitions that decide legality (3:24)
- Hemp vs marijuana is a lab result, not a plant. Both are Cannabis sativa. The 2018 Farm Bill defines hemp as the plant and its derivatives, extracts and cannabinoids with a delta-9 THC concentration of not more than 0.3 percent on a dry-weight basis; above that it is marijuana, a controlled substance (the 2026 changes to both definitions are in the regulatory section). The lecture’s usage note, that “cannabis” on a label or in a guidance document usually means the THC content has not been stated, is her reading of the documents, not a legal definition.
- Non-intoxicating is the clearer word. The lecture draws a line between acting on the central nervous system and intoxicating: hemp-derived CBD does the first and not the second, THC does both. The terms psychoactive and psychotropic are used inconsistently, so for clients say simply that CBD is non-intoxicating and THC is not.
- Hemp seed oil is not CBD. Seed-pressed oil contains essentially no cannabinoids; it is a culinary and cosmetic ingredient. Many “hemp oil for pets” listings are exactly this. If the certificate of analysis does not state cannabinoid content, the content cannot be assessed.
- Extract types: full spectrum (whole plant, THC included), broad spectrum (whole plant minus THC), isolate (CBD alone). These are commercial terms rather than standardized guarantees of composition; the batch-specific analysis is what counts. The lecture discusses the entourage and dose-response hypotheses behind whole-plant extracts; they are hypotheses, not established clinical comparisons among veterinary products. Its concrete point is that dogs’ sensitivity to THC, tied in the lecture to receptor density in the canine cerebellum, argues for products with THC removed.
The endocannabinoid system in one page (13:15)
Three components, present in all vertebrates and characterized only recently (CB1 was characterized in 1988 and cloned in 1990; CB2 was cloned in 1993). Receptors: CB1, the most abundant G-protein-coupled receptor in the brain, largely inhibits neurotransmitter release, modulates neuronal excitability and synaptic plasticity, and is where THC acts on memory, pain, emotion, and appetite. CB2 lives mostly peripherally, is upregulated by inflammation and immune activation, and is an immunomodulatory mediator. Endocannabinoids: anandamide (AEA) and 2-AG, made on demand rather than stored. Degradative enzymes: FAAH and MAGL, which end the signal quickly.
The system’s defining feature is retrograde signaling: endocannabinoids made by the postsynaptic neuron travel backward and reduce presynaptic transmitter release. The network effect depends on the synapse: suppressing an inhibitory input disinhibits the target neuron (depolarization-induced suppression of inhibition), suppressing an excitatory input reduces excitation.
The lecture uses that feedback role to explain why the system keeps turning up in pain, anxiety and seizure research. It is a rationale for studying the system, not evidence that modulating it does anything in a patient.
Two dog-specific points. In cell-system work CBD does not occupy THC’s binding site on CB1; it has been described as a negative allosteric modulator of the receptor and as an inhibitor of FAAH, which would prolong the animal’s own anandamide signaling. Those are in-vitro findings that vary by species and experimental system, not an established mechanism in dogs.
The lecture also notes that dogs carry a higher density of cannabinoid receptors in the cerebellum than people do, offered as the reason THC produces the classic static ataxia in dogs; whatever the mechanism, THC-containing products need particular care in this species.
The four veterinary studies: design, dose, endpoints, limits (44:36)
| Study | Design | Dose used | What was measured, tolerance findings, limits |
|---|---|---|---|
| Cornell, osteoarthritis (Gamble 2018) | Randomized, placebo-controlled, owner- and veterinarian-blinded crossover; 22 client-owned dogs enrolled, 16 completed; NSAIDs, fish oil and glucosamine/chondroitin allowed if unchanged for 4 weeks before and during; gabapentin and tramadol stopped at least 2 weeks before | 2 mg/kg PO q12h, 4 weeks per arm, 2-week washout (PK phase: single doses of 2 and 8 mg/kg in 4 beagles) | Measured: owner CBPI and Hudson activity scores and a veterinary pain assessment at weeks 2 and 4; CBC and chemistry at each visit. PK: median elimination half-life 4.2 h at both doses. Tolerance: no owner-reported side effects; alkaline phosphatase rose during the CBD period (p under 0.01), flagged by the authors as worth monitoring, clinical significance unresolved. Limits: single site, 4-week arms, 16 analyzed. Outcome data: PMID 30083539. |
| Colorado State, idiopathic epilepsy (McGrath 2019) | Randomized, blinded, placebo-controlled; 26 client-owned dogs with intractable idiopathic epilepsy (12 CBD, 14 placebo); oil added to existing antiepileptic drugs | 2.5 mg/kg PO q12h, 12 weeks | Measured: seizure frequency against baseline, responder status defined as a 50 percent or greater decrease, plasma CBD concentrations, adverse effects. Withdrawals: 2 CBD-group dogs for ataxia; 9 CBD and 7 placebo dogs analyzed after other exclusions. Tolerance: serum alkaline phosphatase rose significantly in the CBD group; no adverse behavioral effects reported by owners. Limits: 16 analyzed; the authors call for a higher-dose study. Outcome data: PMID 31067185. |
| Healthy dogs and cats, PK and 12-week tolerance (Deabold 2019) | 8 healthy dogs (CBD-infused soft chew) and 8 healthy cats (CBD-infused fish oil); single-dose PK screening; the only one of the four to include cats | 2 mg/kg total CBD PO q12h for 12 weeks (single-dose PK at 2 mg/kg) | Measured: serum CBD pharmacokinetics; CBC and chemistry every 4 weeks. PK: cats receiving the oil reached far lower serum concentrations than dogs receiving the chew, read by the authors as different absorption or elimination; species and formulation differed. Total CBD in this study means CBD plus CBDA. Tolerance: one cat with a persistent ALT rise above the reference range; cats showed excessive licking and head-shaking during oil dosing; dogs had occasional loose stool. Limits: healthy animals, 8 per species, no placebo arm. Data: PMID 31635105. |
| 90-day OA pilot, full-spectrum hemp (Kogan 2020) | Open-label pilot, no placebo; 37 dogs with chronic maladaptive pain from OA, most from one pain-management practice; NSAIDs, tramadol and amantadine not allowed; gabapentin, Adequan and chondroprotectants allowed; oil supplied and clinic costs reimbursed by the manufacturer | Full-spectrum hemp extract in hemp seed oil, escalated at 2-week intervals to final doses of 0.3 to 4.12 mg/kg twice daily | Measured: veterinary pain assessment and owner questionnaires over 90 days; concurrent gabapentin use tracked (23 of 37 on it at enrollment). Completion: 32 of 37. Tolerance: no adverse effects reported. Limits: open-label, industry-supplied product, not MEDLINE-indexed. Data: AHVMA Journal 2020;58:35-45. |
Read as a set: two controlled canine trials (4 and 12 weeks, 16 dogs analyzed in each), one open-label pilot with an industry-supplied product, and one healthy-animal tolerance study that is the only one of the four to include cats. All four are small and short.
What repeats across them is pharmacologic, not clinical: the one study that included cats found lower serum exposure in cats than in dogs (with different formulations in the two species), and alkaline phosphatase rose in both controlled canine trials. Efficacy conclusions belong to the papers, and the lecture is explicit that it is reporting literature, not making a claim.
Tolerance data, hepatic enzymes and CYP450 interactions (51:36)
In people, a 2011 review of the human literature reported chronic use and doses up to 1,500 mg per day as well tolerated and listed inhibition of hepatic drug metabolism among the reported effects (Bergamaschi 2011); a human review cannot establish veterinary safety, and milligram-per-day human doses do not translate to milligram-per-kilogram animal protocols.
In animals, the largest denominator is the National Animal Supplement Council’s member-reported adverse-event system. The lecture quotes NASC’s November 2019 report: roughly 56 million hemp-product administrations, most in dogs, with nine adverse events reported in dogs, one in a cat, three in horses and none serious. Those numbers are a 2019 snapshot.
NASC’s published surveillance for hemp-derived products sold for dogs from 2010 to 2023 (Bookout 2024) reports about 2.1 adverse events and 0.01 serious adverse events per million administrations sold. Read them for what they are: complaint counts against estimated units sold, compiled and published by the industry council, not active surveillance of followed patients, so they are not incidence rates.
The two standing cautions from the studies: alkaline phosphatase rises in a share of dogs (clinical significance unresolved; monitor), and CBD shares cytochrome P450 metabolism with much of the small-animal formulary, so treat anticoagulants, anticonvulsants and other narrow-margin drugs as interaction-watch patients; the lecture’s interaction list is a watch list, not a list of documented reactions. The lecture’s monitoring recommendation is plain: any animal on chronic CBD should be under veterinary care with baseline and follow-up bloodwork.
Product quality: the part clients cannot see (32:50)
The market’s reference study (Bonn-Miller 2017, JAMA): of 84 CBD products bought online in 2016, 69 percent were mislabeled against measured content (43 percent under-labeled, 26 percent over-labeled), and THC was detected in 18 of the 84.
The pet shelf has its own data: in a 2020 Cornell analysis of 29 over-the-counter veterinary hemp products, measured CBD ranged from 0 to 88 mg per mL or gram, only 10 of the 27 labeled products were within 10 percent of their stated total cannabinoid content (median 93 percent of claim, range 0 to 154 percent), 22 of 29 could supply a third-party certificate of analysis, and 4 of 29 carried heavy-metal contamination, lead most often (Wakshlag 2020). The teachable skill is reading a batch-specific certificate of analysis:
- What should be there: total CBD, total cannabinoids (they differ when minor cannabinoids such as CBG, CBC or CBN are included), and the terpene profile, all matching the label.
- What should not: pesticide and chemical residues, microbial growth, mycotoxins, and heavy metals. Hemp takes up soil contaminants readily, which is why cultivation practices and batch testing matter.
- What drives cost: concentration, cultivation practices, and extraction method (supercritical CO2 or ethanol, each legitimate when done well); judge a product by its analysis, not its price.
- THC persistence: the lecture’s reminder that cannabinoids are detectable far longer than most screened substances, so a mislabeled product is not a trivial exposure for an owner who is drug-tested, or for a dog given a THC-containing dose nobody intended.
Regulatory requirements, as recorded and as of now (25:57)
The lecture’s regulatory chapter, recorded in 2020, still frames the requirements correctly: the 2018 Farm Bill legalized hemp; marijuana is a controlled substance; Epidiolex, a purified CBD, is the only FDA-approved CBD drug (approved June 25, 2018; the lecture misspeaks the year); and no cannabinoid product is approved for animals.
Two rules follow, and they are separate. First, any product marketed with disease or therapeutic claims is a drug by intended use, and an unapproved one, whatever it contains; FDA’s warning letters to pet CBD sellers quote exactly such claims. Second, because CBD is the active ingredient of an approved drug, it cannot be added to food, including animal food and treats, or sold as a dietary supplement, and no CBD ingredient has an approved food-additive petition or GRAS status for animal feed.
The lecture’s own practice of not linking studies from product pages is a conservative reading of the intended-use test: marketing material can establish what a product is for. State veterinary boards remain a patchwork on what vets may discuss or recommend, which is why the lecture points to the interactive state-guidance map maintained on this site.
What has changed since the recording, verified September 29, 2026: the state map has kept expanding: 41 states plus the District of Columbia allow medical cannabis and 24 states plus DC allow adult use (National Conference of State Legislatures counts as of June 26, 2025), against the lecture’s 33 and 11.
Epidiolex now carries three indications (Lennox-Gastaut syndrome, Dravet syndrome and tuberous sclerosis complex) for patients 1 year and older, since July 31, 2020. There is still no FDA-approved, conditionally approved or indexed animal drug containing CBD; FDA’s Center for Veterinary Medicine said so in its January 16, 2025 request for information on cannabis-derived products in veterinary practice (docket FDA-2024-N-5976), and it issued CBD warning letters to pet-product sellers in April 2025.
Two federal definitions are moving: a law of November 12, 2025 rewrites hemp around total THC and, from November 12, 2026, excludes finished hemp-derived cannabinoid products with more than 0.4 milligrams of total THC per container; and on April 28, 2026 the Drug Enforcement Administration moved FDA-approved drug products containing marijuana, and marijuana handled under state medical-marijuana licenses, to Schedule III, with the broader rescheduling of marijuana still pending.
Some states have written veterinarians into law: California’s AB 1885 (2022) bars its board from disciplining a veterinarian solely for discussing or recommending cannabis for an animal, within a veterinarian-client-patient relationship and short of negligence. And the feline literature is no longer one study deep: an escalating-dose tolerance study in healthy cats (Kulpa 2021) and a long-term daily-feeding study (Coltherd 2024) have been published since. The lecture’s own posture, teaching mechanism and evidence without product claims, is the one these notes follow.
Frequently asked questions
What do I tell a client who is going to buy CBD no matter what I say?
Teach the certificate of analysis: cannabinoid content matching the label, THC status stated, residues, microbes, metals and mycotoxins screened.
Ask for a label with a stated cannabinoid concentration per mL and directions written for the species (the lecture’s own example was a human brand whose pet product gave no workable way to dose a dog), ask them to tell you the product and dose so it lives in the record, and schedule bloodwork if use will be chronic.
Board positions on discussing and recommending CBD vary by state, and a few states have written explicit protection into law (California in 2022); check your board’s position, then have the conversation, because it keeps you in the loop.
Which patients deserve extra caution?
Patients on drugs with cytochrome P450 metabolism and narrow margins: anticoagulants, anticonvulsants, some cardiac and behavioral medications. Add patients with pre-existing hepatic disease, given the recurring ALP and ALT observations, and cats generally, whose absorption kinetics differ and whose evidence base, one study at the time of the lecture, is still thin: an escalating-dose tolerance study and a long-term feeding study have been added since.
Whether use is appropriate at all is an individualized call on the patient, the drug list and the product; monitoring does not make a poor candidate a good one.
Is there an approved veterinary cannabinoid product I can prescribe?
No. Epidiolex is human-labeled, and no FDA-approved, conditionally approved or indexed animal drug contains CBD, per FDA’s January 2025 request for information. Everything else in the animal space is sold outside an approval pathway, which is exactly why product quality varies so widely and why the COA, not the label art, is the document that matters. Confirmed against FDA’s Center for Veterinary Medicine statements as of September 2026.
Watch the full lecture
The full hour includes the receptor-density illustrations, the complete study walk-throughs and the state-guidance discussion. Watch it free and earn the credit: CBD for Pets (1 CE hour). Watch at least 75 percent, pass the six-question quiz at 70 percent, and the certificate is issued on the spot and emailed to you.
This program has been RACE approved for 1 hour of continuing education credit (Medical category) in jurisdictions that recognize RACE approval. RACE program number 20-1211620, provider number 50-29133, approved through 2028-06-11. RACE does not accredit, endorse, or certify any program or person, nor does RACE approval validate the content of the program.
References
- Kogan L, Schoenfeld-Tacher R, Hellyer P, Rishniw M. US veterinarians’ knowledge, experience, and perception regarding the use of cannabidiol for canine medical conditions. Front Vet Sci. 2019;5:338. PMID 30687726.
- Gamble LJ, Boesch JM, Frye CW, et al. Pharmacokinetics, safety, and clinical efficacy of cannabidiol treatment in osteoarthritic dogs. Front Vet Sci. 2018;5:165. PMID 30083539.
- McGrath S, Bartner LR, Rao S, Packer RA, Gustafson DL. Randomized blinded controlled clinical trial to assess the effect of oral cannabidiol administration in addition to conventional antiepileptic treatment on seizure frequency in dogs with intractable idiopathic epilepsy. J Am Vet Med Assoc. 2019;254(11):1301-1308. PMID 31067185.
- Deabold KA, Schwark WS, Wolf L, Wakshlag JJ. Single-dose pharmacokinetics and preliminary safety assessment with use of CBD-rich hemp nutraceutical in healthy dogs and cats. Animals (Basel). 2019;9(10):832. PMID 31635105.
- Kogan L, Hellyer P, Downing R. The use of cannabidiol-rich hemp oil extract to treat canine osteoarthritis-related pain: a pilot study. J Am Holist Vet Med Assoc. 2020;58:35-45. Not MEDLINE-indexed.
- Bonn-Miller MO, Loflin MJE, Thomas BF, Marcu JP, Hyke T, Vandrey R. Labeling accuracy of cannabidiol extracts sold online. JAMA. 2017;318(17):1708-1709. PMID 29114823.
- Wakshlag JJ, Cital S, Eaton SJ, Prussin R, Hudalla C. Cannabinoid, terpene, and heavy metal analysis of 29 over-the-counter commercial veterinary hemp supplements. Vet Med (Auckl). 2020;11:45-55. PMID 32346530.
- Bergamaschi MM, Queiroz RH, Zuardi AW, Crippa JA. Safety and side effects of cannabidiol, a Cannabis sativa constituent. Curr Drug Saf. 2011;6(4):237-249. PMID 22129319.
- Bookout W, Dziwenka M, Valm K, Kovacs-Nolan J. Safety study of cannabidiol products in healthy dogs. Front Vet Sci. 2024;11:1349590. PMID 38496308. Funded by the National Animal Supplement Council.
- Kulpa JE, Paulionis LJ, Eglit GM, Vaughn DM. Safety and tolerability of escalating cannabinoid doses in healthy cats. J Feline Med Surg. 2021;23(12):1162-1175. PMID 33769105.
- Coltherd JC, Bednall R, Bakke AM, et al. Healthy cats tolerate long-term daily feeding of cannabidiol. Front Vet Sci. 2024;10:1324622. PMID 38327816.
- US Food and Drug Administration. FDA regulation of cannabis and cannabis-derived products, including cannabidiol (CBD): questions and answers.
- Drugs@FDA. Epidiolex (cannabidiol) oral solution, NDA 210365: original approval June 25, 2018; new indication July 31, 2020.
- US Food and Drug Administration, Center for Veterinary Medicine. Use of cannabis-derived products, including cannabidiol, in veterinary practice; request for information. Federal Register, January 16, 2025, docket FDA-2024-N-5976.
- Agriculture Improvement Act of 2018, Pub. L. 115-334, sec. 10113 (7 U.S.C. 1639o), as amended by Pub. L. 119-37 (November 12, 2025; effective November 12, 2026).
- Drug Enforcement Administration. Schedules of controlled substances: rescheduling of Food and Drug Administration approved products containing marijuana from schedule I to schedule III; corresponding change to permit requirements. Final rule, Federal Register, April 28, 2026 (FR Doc. 2026-08176).
- National Conference of State Legislatures. State medical cannabis laws. Counts as of June 26, 2025; page updated September 2, 2026.
- National Animal Supplement Council. Ingredient risk report, hemp and hemp-derived compounds, November 2019, as presented in the lecture.
- California Assembly Bill 1885, Stats. 2022, ch. 389 (Bus. and Prof. Code sec. 4884).
Related resources on this site: the owner-facing CBD guides for dogs and cats. Educational content provided by Dr. Fossum’s Pet Care.
These notes summarize a recorded continuing-education lecture for veterinary professionals. They are educational, not clinical guidelines; decisions about an individual patient belong to the attending veterinarian.