- Distinguishing features
- Marijuana is an annual herb 6-10 feet tall with palmately compound leaves; leaflets are narrow, long, and coarsely serrate; flowers are small and green in clusters in the axils of the upper leaves; marijuana is dioecious.
- An annual plant growing to 6 feet in height. The stem is erect and multibranched. Palmate leaves are opposite toward the base and alternate at the top, with 5-11 leaflets each. Male and female flowers grow on separate plants and are greenish-white.
- Geographic range
- Grows across the United States in most soil types. Often found in soils, as well as in illegal cultivation. Cannabis is a common roadside weed in the midwestern United States.
- Toxic principle
- More than 60 cannabinoid compounds have been isolated from C. sativa. Tetrahydrocanibinol (THC) is the compound most toxic to the nervous system.
- Animals are rarely poisoned because of the low palatability of the plant. However, cattle, horses, pigs, ferrets, and dogs are susceptible to intoxication after exposure. THC concentrations are highest in flowers and leaves.
- Mechanism of toxicologic damage
- Cannabinoids are rapidly absorbed from smoke and more slowly absorbed post-ingestion. They are rapidly metabolized by the mixed-function oxidase system in the liver. Toxic effects are mainly in the central nervous system, repiratory system, and endocrine system.
- Clinical signs
- CNS depression is the most commonly observed sign of poisoning in dogs. Hyperexcitability, vomiting, salivation, muscle tremors, and ataxia may also be seen in intoxicated animals. Intoxication usually lasts a few hours. In severe cases, coma and death are rarely seen.
- Mild intoxication requires only close observation and sedation. Induced emesis, oral activated charcoal, and bowel evacuation may be helpful in reducing clinical signs in severe cases. Body temperature should be closely monitored.
C. sativa is one of the oldest cultivated plants. It was first grown in China 6,000 years ago and has historically been used to treat various medical symptoms including insomnia, migraine headaches, and asthma. Today, marijuana is used medicinally to treat glaucoma and to relieve some of the side-effects of cancer therapy. In the United States, medicinal use of marijuana is controversial and use of marijuana without a prescription is illegal.