Andre emphasizes that approval of cannabis-based products for use in food animals likely will require science-based withdrawal times and extensive testing to avoid cannabinoid residues in meat or milk.
Hemp products, on the other hand, while still regulated at the federal level, probably face an easier path toward licensing and commercial veterinary use, particularly in food animals. But even for CBD extracted from hemp, Andre says, manufacturers will need to develop uniform, proven methods for growing, extracting, storing and administering the products for consistent, predictable results.
The situation somewhat resembles the early days of commercial ethanol production. Distillers’ grains established value as a byproduct feed for livestock, but producers and nutritionists struggled with inconsistencies in quality and feed value. Over time, the distilleries worked to capture more value by adopting processes that improved the consistent quality of distillers’ grains for feed.
Stephanie McGrath, DVM, MS, ACVIM, is an assistant professor in veterinary neurology and neurosurgery at Colorado State University. She has conducted studies using CBD-dominant (or hemp products) products in dogs for several years, and says regulatory changes now have made it easier to legally research THC as well. She believes CBD in particular has significant potential in veterinary medicine, but more research is needed.
McGrath has conducted safety tests to evaluate delivery methods, dosage and side effects, and randomized, controlled experiments testing CBD treatments for epilepsy and arthritis in dogs. Her tests indicate, first, that the treatments are extremely safe. She’s found some moderate improvements in treated animals versus controls, but the improvements were not large enough to recommend changing from conventional treatments. The pilot studies used small sample sizes though, and she says questions remain regarding optimal doses and delivery methods such as topical, transdermal or oral for various treatments.
Looking ahead, she believes research could show benefits in anxiety relief, appetite stimulation and reductions in side effects from cancer treatments in companion animals. Just as in human medicine, she says, the consequences of reducing stress are positive overall for patient outcomes, and stress reduction could prove a key application in food animals.
Stephen Cital, RVT, RLAT, SRA, VTS-LAM, is the COO for the Veterinary Anesthesia Nerds and Veterinary Cannabis Academy, the Executive Director for the Academy of Laboratory Animal Veterinary Technicians and Nurses and Chair Elect for the Committee on Veterinary Technician Specialties. He envisions a bright future for cannabis in veterinary medicine, but acknowledges that the research to enable therapeutic uses in food animals will take time.
Biomass from hemp production, including leaf material and seeds, already finds its way into animal feeds, and research shows considerable benefits, with the seeds in particular containing valuable fatty acids for enhancing livestock nutrition, Cital says. After the seeds are crushed for oil production, the remaining hulls and meal can provide a high-quality feed, as with soy and cottonseed. These products contain no significant levels of cannabinoids, and thus are not subject to specific regulations.
Figure 1. We asked farmers and ranchers their opinion about using cannabis in animals. Here's what they said.
He has no doubt that research will verify efficacy of CBD and THC-containing products for therapeutic applications in livestock, but concerns over residues and determination of withdrawal times will require extensive research and testing.
Cital notes that research also has suggested that biomass produced in hemp processing contains terpenes with antifungal properties. Anecdotal evidence from farmers using the material in livestock bedding suggests it could help reduce fungal infections in animals’ feet and respiratory systems.
Recent research, Cital says, indicates cannabinoids could improve in-vitro bovine oocyte maturation.
Poultry research using rations based on hemp seeds shows higher triglyceride levels in egg yolks, suggesting the product could help make eggs healthier (see Research Evaluates Multiple Applications below).
FDA serves as gatekeeper
The farm bill’s relaxation of regulations on growing commercial hemp likely will boost supplies of hemp byproducts considerably. However, the FDA has clearly stated that medicinal claims for cannabis products will face the same scrutiny as other new drugs.
“We continue to be concerned at the number of drug claims being made about products not approved by the FDA that claim to contain CBD or other cannabis-derived compounds,” says FDA Commissioner Scott Gottlieb, MD. “Among other things, the FDA requires a cannabis product (hemp-derived or otherwise) that is marketed with a claim of therapeutic benefit, or with any other disease claim, to be approved by the FDA for its intended use before it may be introduced into interstate commerce. This is the same standard to which we hold any product marketed as a drug for human or animal use.”
Gottlieb goes on to say that selling unapproved products with unsubstantiated therapeutic claims is not only a violation of the law, but also can put patients at risk, as these products have not been proven to be safe or effective.
The FDA is, however, open to approval of cannabis-derived drugs, given adequate testing to ensure safety and efficacy. In June 2018, the FDA approved Epidiolex CBD oral solution for the treatment of seizures associated with two rare and severe forms of epilepsy: Lennox-Gastaut syndrome and Dravet syndrome. This is the first FDA-approved drug that contains a purified drug substance derived from marijuana. It is also the first FDA approval of a drug for the treatment of patients with Dravet syndrome.
Hemp products used in food or feed face an easier path to acceptance. Gottlieb notes that some foods are derived from parts of the hemp plant that may not contain cannabinoids, meaning that their addition to foods might not raise the same issues as the addition of drug ingredients like CBD and THC.
In 2018, FDA announced completed evaluation of three Generally Recognized as Safe (GRAS) notices related to hulled hemp seeds, hemp seed protein and hemp seed oil and that the agency had no questions regarding conclusions that the use of such products as described in the notices is safe. “Therefore, these products can be legally marketed in human foods for these uses without food additive approval, provided they comply with all other requirements and do not make disease treatment claims,” he says.
Research Evaluates Multiple Applications
Recent research, and even some dating back to the 1970s, explores a variety of potential uses for cannabis components in veterinary medicine. Following are a few sample titles illustrating that diversity.
- Cannabinoid-Induced Chemotaxis in Bovine Corneal Epithelial Cells, Investigative Ophthalmology and Visual Science, 2015
- Antimicrobial activity of Cannabis sativa, Thuja orientalis and Psidium guajava leaf extracts against methicillin-resistant Staphylococcus aureus, Journal of Integrative Medicine, 2018
- Exocannabinoids effect on in vitro bovine oocyte maturation via activation of AKT and ERK1/2, Reproduction, 2016
- Pharmacological Properties of Cannabinoid Receptors in the Avian Brain: Similarity of Rat and Chicken Cannabinoid1 Receptor Recognition Sites and Expression of Cannabinoid2 Receptor-Like immunoreactivity in the Embryonic Chick Brain, Pharmacology & Toxicology, 2001
- Diet-induced changes in n-3 and n-6 derived endocannabinoids and reductions in headache pain and psychological distress, Journal of Pain, 2015
- Hempseed Products Fed to Hens Effectively Increased n‑3 Polyunsaturated Fatty Acids in Total Lipids, Triacylglycerol and Phospholipid of Egg Yolk, Lipids, 2016
- Increasing Levels of Dietary Hempseed Products Leads to Differential Responses in the Fatty Acid Profiles of Egg Yolk, Liver and Plasma of Laying Hens, Lipids, 2016
- Cannabinols and Feeding in Sheep, Psychopharmacology, 1979
- Performance, egg quality, and blood plasma chemistry of laying hens fed hempseed and hempseed oil, Poultry Science, 2014
- The Effects of Hemp By-Products Feeding on Gut Microbiota and Growth in Broiler Chickens, Mendelnet, 2016
Read more about cannabis in animal feed here:
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