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CBD and epilepsy/ seizure management

Review article

Potschka H, Bhatti SFM, Tipold A & McGrath S 2022, “Cannabidiol in canine epilepsy”, Veterinary Journal, Oct 6:105913. doi: 10.1016/j.tvjl.2022.105913. Epub ahead of print. PMID: 36209995.

CBD and epilepsy - human studies  

  • evidence from controlled trials with CBD in human patients with epileptic encephalopathies has only recently become available

  • clinical data from human patients support a relevant antiseizure effect with efficacy against various seizure types.

  • placebo-controlled, randomized trials have been conducted in human patients with different epileptic and developmental encephalopathies,  all characterized by difficult-to-treat seizures with a high rate of drug resistance

  • Safety – randomized blinded controlled trials and open label extension trials in human patients confirmed an acceptable safety profile of CBD. The most common adverse effects comprised diarrhea, pyrexia, decreased appetite and somnolence


 Drug-refractory canine epilepsy:

  •  McGrath et al., 2019 – see below for summary

  • Garcia et al., 2022 - see below for summary



Studies generally confirm tolerability and safety


  • Vaughn et al., 2020 

  • Deabold et al., 2019

  • Chicoine et al., 2020

  • (click here for more information about these)


First reported rare case of a suspected severe cutaneous adverse reaction to CBD: 

(Simpson, A.C., Bradley, C.W., Schissler, J.R., 2020. Probable cutaneous adverse drug reaction due to a cannabidiol-containing hemp oil product in a dog. Veterinary Dermatology 31, 404–e108)


Author’s conclusions about CBD and canines

  •  consider the pharmaceutical quality of the CBD formulation,

  • avoid CBD formulations with > 0.2 % THC

  • closely monitor ALP levels.

  • Titre dose, and dose < 10 mg/kg CBD

McGrath S, Bartner LR, Rao S, Packer RA & Gustafson DL 2019, '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', Journal of the American Medical Association, vol. 254, no. 11, pp. 1301-1308.


Objective: To assess the effect of oral cannabidiol (CBD) administration in addition to conventional antiepileptic treatment on seizure frequency in dogs with idiopathic epilepsy.


Design: Randomized blinded controlled clinical trial.


Animals: 26 client-owned dogs with intractable idiopathic epilepsy – 17 finished the study.


Inclusion criteria comprised:

1) a tier II confidence level for diagnosis of idiopathic epilepsy

2) at least two epileptic seizures per month for a minimum of 16 weeks;

3) treatment with at least one conventional ASM; and

4) phenobarbital or potassium bromide concentrations in the therapeutic range and/or administration of zonisamide or levetiracetam at recommended doses.



  • Dogs were randomly assigned to a CBD (n = 12) or placebo (14) group.

  • The CBD group received CBD-infused oil (2.5 mg/kg BID) for 12 weeks in addition to existing antiepileptic treatments,

  • The placebo group received oil without CBD under the same conditions.

  • Seizure activity, adverse effects, and plasma CBD concentrations were compared between groups.



  • Dogs in the CBD group had a significant (33%) reduction in seizure frequency, compared with the placebo group.

  • the number of responders with an at least 50 % reduction in seizure frequency proved to be identical in both dog groups.

  • Plasma CBD concentrations were correlated with reduction in seizure frequency.  Possibly need higher doses?

  • Dogs in the CBD group had a significant increase in ALP

Garcia, GA, Kube, S, Carrera-Justiz, S, Tittle D & Wakshlag JJ 2022, “Safety and efficacy of cannabidiol-cannabidiolic acid rich hemp extract in the treatment of refractory epileptic seizures in dogs”, Frontiers in Veterinary Science, vol. 29, 9:939966.


Design: randomized blinded clinical trial


Sample: 14 dogs with idiopathic or presumed idiopathic epilepsy


Inclusion criteria:

  • treated for over a year and remained only partially responsive to common highest tolerable doses of medication, yet still having at least one epileptic event per month



  • dogs receiving placebo or capsule containing CBD/CBDA-rich hemp extract in a sesame oil preparation.

  • Dose: as close to 2 mg/kg body weight BID PO.

  • Treatment was switched after 3 months.



  • During CBD/CBDA exposure, seizure frequency as well as the number of days with seizure activity were significantly lower than during the placebo phase

  • 6/14 dogs - had a ≥ 50 % reduction in seizure frequency in the CBD/CBDA treatment phase

    • No respective reduction for dogs in the placebo group.

  • Except for mild increases in ALP, there were no changes in blood counts and serum chemistry became evident.

  • The data argued against a relevant impact on serum concentrations of phenobarbital, zonisamide, and bromide.

  • Adverse events were minor with somnolence and ataxia observed in three and four dogs, respectively

Mogi, C & Fukuyama, T 2019, ‘Cannabidiol as a potential anti-epileptic dietary supplement in dogs with suspected epilepsy: three case reports’, Pet Behaviour Science, vol. 7, pp. 11 –16


1.    Case 1: 3-year 2-month-old, 33-kg MN Labrador Retriever, seizures since 6 mths of age.  Approx 6 seizures per year
2.    Case 2: 11-year 2-month-old, 4-kg MN Papillon.  Seizures since 3 years old
3.    Case 3: 10-year 2-month-old, 2-kg male Chihuahua.  Seizures since 3 years old


They administered CBD BID PO for 8 weeks.  Used CBD-containing full-spectrum hemp extract

  • Case 1: dosage CBD @ 0.51mg/kg/day

  • Case 2:  dosage @ 1.25mg/kg/day

  • Case 3:  dosage @ 5.0mg/kg/day


•    Case 1: fewer seizures, less excitable.  Owner felt the dog showed improvement.  
•    Case 2: symptoms unchanged but dog settled down and slept longer
•    Case 3: owner felt that seizure-like behaviour decreased slightly with treatment. The owner also reported that the dog showed less aggression toward familiar people, such as the owner’s children 

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