Cannabis toxicity

From Dog

Cannabis sativa (marijuana) is a common recreational drug worldwide and accidental ingestion or inhalation by dogs has been reported[1].

Cannabis is poorly absorbed from the canine gut and inhalation appears to induce many of the clinical symptoms. This drug, which has both anticonvulsant and antiepileptic properties[2], produce a biphasic parasympathomimetic/sympathetic response, inducing bradycardia, hyperglycemia[3], pulmonary hypertension[4] and reduced intraocular pressure[5].

Toxicity signs develop after a minimum dose ingestion of 84.7 mg/kg of the active ingredient cannabidiol, with toxicity developing within 5 minutes and may persist for 3 - 4 days, depending on dog's age and duration of exposure[6].

Although rarely fatal, ingestion of this weed often results in neurological and gastrointestinal symptoms which are often dose-related and long term use results in temporary infertility in dogs[7].

Clinically affected dogs often present with whole body tremors, behavioral changes, facial and pedal pruritus and conjunctivitis[8].

Treatment usually consists of supportive therapy including intravenous fluids, diazepam and thermoregulation.

Most dogs recover from acute toxicity, although intermittent temporary psychotrophic effects have been reported up to 6 months post-exposure.


  1. Botha CJ & Penrith ML (2009) Potential plant poisonings in dogs and cats in southern Africa. J S Afr Vet Assoc 80(2):63-74
  2. Samara E et al (1988) Pharmacokinetics of cannabidiol in dogs. Drug Metab Dispos 16(3):469-472
  3. de Pasquale A et al (1978) The influence of cannabis on glucoregulation. Bull Narc 30(3):33-41
  4. Jandhyala BS et al (1976) Effects of acute administration of delta9-tetrahydrocannabinol on pulmonary hemodynamics of anesthetized dogs. Eur J Pharmacol 38(1):183-187
  5. Merritt JC et al (1981) Topical delta 9-tetrahydrocannabinol and aqueous dynamics in glaucoma. J Clin Pharmacol 21(8-9):467S-471S
  6. Janczyk P et al (2004) Two hundred and thirteen cases of marijuana toxicoses in dogs. Vet Hum Toxicol 46(1):19-21
  7. Dixit VP et al (1977) Testicular degeneration and necrosis induced by chronic administration of cannabis extract in dogs. Endokrinologie 69(3):299-305
  8. Evans AG (1989) Allergic inhalant dermatitis attributable to marijuana exposure in a dog. J Am Vet Med Assoc 195(11):1588-1590