Hemp, also known as Cannabis sativa, is a plant that has been cultivated for centuries due to its versatile uses. Hemp can be used to produce paper, fabrics, ropes, biodegradable plastic, fuel, and antibacterial detergents, among others. It is also used as a food source, with products such as flour, oils, seeds, herbal teas, and beer being obtained from hemp. Hemp flowers have been used for both curative and recreational purposes due to their psychotropic effects. The plant contains nearly 500 chemical compounds, including phytocannabinoids, terpenes, flavonoids, amino acids, fatty acids, vitamins, and macro- and micro-elements, among others. Hemp products have been authorized in some countries for therapeutic purposes as a second-choice approach for clinical conditions such as pain and inflammation, epilepsy, anxiety disorders, nausea, emesis, and anorexia, among others.

Hempseed and hempseed meals are rich sources of protein, polyunsaturated oils, vitamins, and minerals. Whole hempseed contains about 20-25% protein, 25-35% carbohydrates, 25-35% oil, vitamins, and minerals. Hempseed contains two main proteins, edestin and albumin, which contain significant amounts of all essential amino acids. In addition, hempseed contains amino acids arginine and glutamic acid at exceptionally high levels, as well as good amounts of sulfur-containing amino acids methionine and cystine. The oil obtained from hempseed is characterized by a great amount of the two essential fatty acids (EFAs) linoleic acid (LA, 18:2 ω-6) and α-linoleic acid (ALA), resulting in a 3.5:1 ratio of Omega-6 to Omega-3. Hempseed oil also tends to contain high amounts of metabolites of LA and ALA, such as γ-linolenic acid (GLA) and stearidonic acid (SDA, Omega 3), respectively. Hempseed and hempseed cakes contain tocopherols, especially γ-tocopherol.

Hemp has been evaluated for use in animal nutrition. Hempseed and hempseed cakes could be used as feed materials for all animal species, although with species-specific differences with regard to the rate of inclusion in the diet. Hemp oil can be used as a supplement in feed mixtures for animals as a rich source of essential fatty acids, while seeds and hempseed cakes can be used as a fat and protein source in animals' diets. Several studies have evaluated the effects of the intake of hempseed or its products in animals, albeit with results not always conclusive.

Hemp contains a considerable number of active ingredients, mainly represented by phytocannabinoids, terpenes and terpenoids, and flavonoids, as well as saturated and unsaturated fatty acids, proteins, carbohydrates, chlorophylls, vitamins, and minerals, among others. Many of the constituents of C. sativa can be classified as either nutrients, nutraceuticals, or pharmaceutical ingredients.
The two most well-known compounds are THC and CBD. THC is responsible for the psychotropic effects of the plant, while CBD is not psychoactive and may counteract the effects of THC. Other compounds in the plant may also contribute to its therapeutic properties. When all the compounds in the plant work together, it is known as the entourage effect.

The body has an endocannabinoid system (ECS) that includes cannabinoid receptors, endocannabinoids (compounds produced by the body that bind to these receptors), and enzymes that synthesize and break down these compounds. The ECS plays a role in many physiological functions, including memory, learning, coordination of motor functions, pain relief, anti-inflammatory response, antioxidant activity, and regulation of sleep, appetite, and reproductive functions. It may also be involved in neuroprotection and control of the proliferation of cancer cells. As a result, the compounds in cannabis that interact with the ECS may be useful in treating a range of conditions.

In humans, cannabis is being investigated as a treatment for conditions such as pain associated with multiple sclerosis, neuropathic pain, anorexia, nausea, and vomiting associated with certain pathologies or their treatment, some forms of glaucoma, and epilepsy. In veterinary medicine, cannabis derivatives have been used by some veterinarians to control pain (especially neuropathic, osteoarthritis, and cancer pain), epilepsy refractory to conventional treatments, allergic skin diseases, and mood disorders (such as anxiety) in dogs and cats. However, there is a need for more studies to investigate the efficacy, tolerability, and pharmacokinetics of cannabis derivatives in animals.

Giorgia della Rocca* and Alessandra Di Salvo

published: 28 July 2020 doi: 10.3389/fvets.2020.00387