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Hemp (Cannabis sativa)

ISSN 2398-2950

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Synonym(s): Marijuana, Hemp, Hashish, Mary Jane, Pot, Grass, CBD, THC, Weed

Introduction

  • See Cannabis poisoning Cannabis poisoning.
  • Medicinal hemp differs from medical marijuana in the concentration of cannibidiol (CBD) and tetrahydrocannabinal (THC). Industrial hemp contains high levels of CBD and not more than 0.3% THC on a dry matter basis. Medical marijuana may contain as much as 20% THC and low levels of CBD.
  • Rough-stemmed annual herb (resembles the giant ragweed).
  • Grows to a height of 1-2.5 m.
  • Flowers, leaves and stems covered with hairs which exude a sticky resin.
  • Leaves:
    • Opposite.
    • Long-stalked.
    • Each leaf has 5-7 long, pointed, coarsely toothed leaflets.
  • Flowers:
    • 2 kinds: one bearing pollen and one bearing seed.
    • Both kinds are small and green and are borne at the tip of the stem and in the upper axils of the leaves.
    • Small.
    • Green.
    • Clustered.
The US FDA has issued a warning about health risks associated with synthetic cannabinoid products contaminated with brodifacoum, a long-acting anticoagulant commonly used in rat poison. These unapproved products are being sold as substitutes for marijuana under names such as “K2” and “Spice".

Available products

  • Hemp or CBD oil.
  • CPD pet biscuits and treats.
  • CBD gummies.
  • CBD topical creams and ointments.
  • CBD 300 mg capsules.
  • CBD vaporizers.
  • CBD bath bombs.
  • CBD chocolate bars.

Legal considerations

  • Hemp is excluded from the legal definition of marijuana, often leading pet owners to assume it is legally acceptable to purchase and use.
  • Hemp is defined legally in the US as "the mature stalks of such plant, fiber produced from such stalks, oil or cake made from the seeds of such plant, any other compound, manufacture, salt, derivative, mixture, or preparation of such mature stalks (except the resin extracted therefrom), fiber, oil, cake, or the sterilized seed of such plant which is incapable of germination." Note that the leaves are not included in the definition of hemp.
  • Regulatory authorities often recognize and tolerate the cultivation of industrial hemp and its products, but this legal tolerance does not always extend to CBD products that contain more than 0.3% THC.

Medicinal properties

  • Approved indications:
    • Anorexia-cachexia syndrome.
    • Chemotherapy-induced nausea and vomiting.
    • Glaucoma.
    • Multiple sclerosis.
    • Epilepsy.
  • Proposed indications:
    • Anxiety.
    • Depression.
    • Insomnia.
    • Head injury.
    • Migraine headaches.
    • Arthritis.
    • Chronic pain.
    • Muscle spasm.
    • Parkinson's disease.
    • Tourette syndrome.

Toxicity

  • Minimum lethal oral dose in dogs: THC 3 g/kg:
    • CBD pet treats often contain only 2.5-5 mg of THC per treat.
    • CBD oil (0.3% THC) contains 90 mg THC/30 mL.
    • Reputable hemp and CBD product suppliers should provide a certificate of analysis showing both THC and CBD levels.
  • Mainly THC (tetrahydrocannabinol) and related compounds; cannabidiol (CBD), a C21 carboxylic acid:
    • CB1 receptors are found on neurons (especially canine cerebellum) and in the gastrointestinal tract and release GABA.
    • CB2 receptors are found in the immune system.
  • Entire plant, particularly leaves, flowering parts, sap, and resinous secretions.
  • Collateral toxicity from items associated with ingestion, eg chocolate, raisins, xylitol, packaging material.

Clinical signs

  • No clear-cut clinical signs.
  • Similar to those of narcotic poisoning.
  • Onset of symptoms is typically within 1-2 h of exposure but range from 5 mins to 96 h. Duration of symptoms is typically 24  h but may range from 1-5 days depending on degree of exposure.
  • The animal may at first appear highly nervous; later it may give evidence of derangement of the central nervous system and mental depression.
  • Symptoms include:
    • Ataxia and incoordination.
    • Hypersalivation.
    • Depression.
    • Disorientation.
    • Hypothermia or hyperthermia.
    • Mydriasis.
    • Tachycardia or bradycardia (higher doses).
    • Vomiting.
    • Tremors.
    • Urinary incontinence.
    • Stupor.
    • Nystagmus.
    • Apprehension.
    • Vocalization.
    • Hyperexcitability.
    • Hyperesthesia (heightened sensitivity to motion, light and sound).
    • Tachypnea.
    • Coma.
  • If death follows, it results from the depressing effect of the poison upon vital centers and organs.

Confirmatory diagnosis

  • Medical history (owner may deliberately withhold for fear of legal repercussions).
  • Stomach content analysis.
  • Urine THC levels (urine tests deigned for humans may not be accurate - false negatives).

Differential diagnoses for marijuana intoxication

  • Opioids.
  • Lysergic acid diethylamide (LSD).
  • Phencyclidine (PCP).
  • Ethanol.
  • Methanol.
  • Isopropanol.
  • Acetone.
  • Macrocyclic lactones (avermectins and milbemycins).
  • Tranquilizers.
  • Depressants.
  • Muscle relaxants Muscle relaxant: overview.
  • Benzodiazepines.
  • Ethylene glycol Ethylene glycol poisoning.
  • Diethylene glycol.
  • Hallucinogenic mushrooms Mushroom poisoning.
  • Amphetamines.
  • Xylitol.

Treatment

  • Emesis if ingestion was within 2 h (contrainidcated if severely depressed or agitated).
  • Activated charcoal Charcoal activated to prevent enterohepatic recycling.
  • Fluid support for vomiting and hypothermia.
  • Monitor body temperature, and heart and respiratory rate every 2 h.
  • Sedation for animals with severe CNS stimulation.
  • Anti-emetics for persistent vomiting.
  • Intravenous lipid therapy Intravenous lipid infusion may be useful for severely poisoned animals.

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Fitzgerald K T, Bronstein A C & Newquist K L (2013) Marijuana poisoning. Topics in Comp Anim Med 28 (1), 8-12 PubMed.
  • Meola S D, Tearney C C, Haas S A et al (2012) Evaluation of trends in marijuana toxicosis in dogs living in a state with legalized medical marijuana: 125 dogs (2005-2010). J Vet Emerg Crit Care 22 (6), 690-696 PubMed.
  • Jancyk P, Donaldson C W, Gwaltney S (2004) Two hundred thirteen cases of marijuana toxicosis in dogs. Vet Human Toxicol 46 (1), 19-21 PubMed.
  • Donaldson C W (2002) Marijuana exposure in animals. Vet Med 97 (6), 437-439 VetMedResource.

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