FAQs about Medical Marijuana in Companion Animals

By Carrie Jurney DVM DACVIM (Neurology) 

With the rise in popularity of medical and recreational marijuana in humans, it follows that people will be curious about using these products in their pets. This is still a tricky subject for the veterinarian, as evidence is lacking and legality is questionable at best for our patient population. 

As a practicing neurologist in San Francisco, it’s a conversation I have frequently. This prompted me to research the efficacy, safety and legality of these products for veterinary patients. Here’s what my investigations have shown: 

Is it legal to prescribe? 

The short answer is medical marijuana is not legal to prescribe for companion animals anywhere in the United States. There has yet to be a state that included veterinarians in the legal language for their medical marijuana laws, so regardless of the laws for human consumption in your state, veterinarians are in no way excluded from the federal law. 

It is equally important to note that the AVMA and the FDA state that these products are not known to be safe nor efficacious. ^{1, 2} When I contacted the Pennsylvania Veterinary Medical Board about their recommendations, they stated that there have been no specific policy or regulations made on this subject. 

What about supplements? 

There are supplements widely available on the internet, many are based on cannabidiol or CBD. There are several pet focused brands. The legal definition of these products is still under debate. In December of 2016 the DEA announced a new definition for marijuana that included CBD as a marijuana extract, and therefore a Schedule 1 substance.³ The Hemp Industry Association has responded, and there is legal action pending, that this designation violates Sec 7606 of the Farm Bill which allows for the legal sale of cannabis based products with less than 0.3% THC.⁴

Is it safe?

Marijuana is a fairly safe product in terms of fatal toxicity. There have been only 2 reported fatalities from marijuana toxicity in 338 clinical cases in the veterinary literature, although one of these studies noted that the volume of cases seen for toxicity has risen sharply with legalization.^5,6

It is also important to note that across many studies in human medicine there are consistent reports of adverse effects associated with medical use. Doses and formulations that would be well tolerated in our veterinary species are still not known. 

An additional concern are reports of pesticides in dispensary obtained marijuana products. In one such report 84% of tested samples had unacceptable levels of pesticides.⁷ Legal regulation and enforcement of pesticide use on marijuana is still in development in most states.  

Does it work?

There is interesting and emerging research on a variety of uses for medical marijuana for conditions like pain, seizures, nausea and cancer. Many of these studies do show statistically significant therapeutic action of these substances. As a neurologist, I have been particularly interested in the current research of CBD in pharmacoresistant epilepsy in children, for which there have been successful trials.^{8, 9} However, it is important to note there is no current evidence for efficacy in veterinary species. The limited bioavailability data we have in dogs does suggest that dogs metabolize these products differently than humans, so we should be cautious when directly translating the human literature to our patient population. ^{10, 11}

The Clinical Pharmacology lab at Auburn University is currently offering free cannabinoid monitoring in hopes of establishing an assay for toxicity and efficacy. You can submit samples via their webform. 

What do I say to my clients?
When asked about these subjects from clients I say the following:

“I understand there is a lot of interesting information out there about marijuana. The truth is that we do not yet know what doses and formulation are safe or have any positive effect in pets. We do know from years of experience that pets can have some negative side effects from marijuana ingestion, so that makes me cautious. The research in humans is really interesting, but very new, and no research has been done in dogs (cats, horses, etc). Additionally, it is illegal for me to prescribe it, as veterinarians are not included in state medical marijuana laws.”

About:

Carrie Jurney DVM DACVIM (Neurology) 
President, Jurney Veterinary Neurology, Redwood City, California

References:

1. AVMA@WorkEditor. “A Sign of the Times: Medical Marijuana Use and Veterinary Medicine.”AVMA@Work Blog. AVMA, 16 July 2013. Web. 01 July 2017.
2. Office of the Commissioner. “FDA and Marijuana: Questions and Answers.” U S Food and Drug Administration Home Page. Office of the Commissioner, 30 June 2016. Web. 01 July 2017.
3. Drug Enforcement Administration. “Establishment of a New Drug Code for Marihuana Extract.” Federal Register. Office of the Federal Registrar, 14 Dec. 2016. Web. 01 July 2017.
4. Hemp Industries Association. “Hemp Industries Association Responds to DEA Final Rule Regarding ‘Marijuana Extracts’.” Hemp Industries Association News & Press Releases Hemp Industries Association, 16 Dec. 2016. Web. 01 July 2017.
5. Meola, Stacy D., et al. “Evaluation of trends in marijuana toxicosis in dogs living in a state with legalized medical marijuana: 125 dogs (2005–2010).” Journal of Veterinary Emergency and Critical Care 22.
6. (2012): 690-696.
   6. Janczyk, Pawel, Caroline W. Donaldson, and Sharon Gwaltney. “Two hundred and thirteen cases of marijuana toxicoses in dogs.” Veterinary and human toxicology 46.1 (2004): 19-20.
7. Angle, Patrick, and Steep Hill Labs, Inc. | Ste. “Steep Hill Launches New High Detection Cannabis Pesticide Testing in California.” Steep Hill Press Release (n.d.): n. pag. Steep Hill Labs, 19 Oct. 2016. Web. 1 July 2017.
8. Devinsky, Orrin, et al. “Cannabidiol in patients with treatment-resistant epilepsy: an open-label interventional trial.” The Lancet Neurology 15.3 (2016): 270-278.
9. Cross, J. Helen, et al. “Cannabidiol (CBD) reduces convulsive seizure frequency in Dravet syndrome: results of a multi-center, randomized, controlled trial (GWPCARE1)(CT. 001).” Neurology 88.16 Supplement (2017): CT-001.
10. Samara, E. M. I. L., M. E. I. R. Bialer, and R. A. P. H. A. E. L. Mechoulam. “Pharmacokinetics of cannabidiol in dogs.” Drug metabolism and disposition16.3 (1988): 469-472.
11. Samara, E. M. I. L., and M. E. I. R. Bialer. “Pharmacokinetics of the dimethylheptyl homolog of cannabidiol in dogs.” Drug metabolism and disposition 16.6 (1988): 875-879.