Marijuana detected in multiple dogs
Travis Mays, MS, PhD
The Texas A&M Veterinary Medical Diagnostic Laboratory (TVMDL) received serum for marijuana testing from three different dogs over a period of five days. Each case was unrelated, and the dogs ranged in age from 1 to 12 years old. Clinical history was not provided. The serum samples were processed using solid phase extraction (SPE). Detection of tetrahydrocannabinol (THC) was performed using a Thermo Scientific™ TSQ Altis™ triple quadrupole mass spectrometer. Estimated serum concentrations of THC ranged from 40 to 80 ng/mL.
THC is the principal psychoactive constituent of cannabis. Exposure to marijuana in companion animals is usually by accidentally ingesting it, although some are exposed via inhalation from second-hand smoke or smoke blown intentionally in their face.1 THC exposure in companion animals may also be the result of administering cannabidiol (CBD) containing products. Due to limited federal regulations and oversight of CBD manufacturing, many CBD products are not certified. Therefore, concentrations of CBD and THC in some products may be unknown or inaccurate, leading to inadvertent exposure to THC in dogs and cats. There is little data in the scientific literature describing the pharmacokinetics of THC resulting from CBD administration in companion animals. One group of researchers observed a mean maximum plasma THC concentration of 10.5 ng/mL following the administration of escalating doses of CBD oil (549 mg CBD; ~53 mg/kg) in dogs.2 Although published data are limited, it is unlikely the estimated concentrations of THC observed in the three dogs tested by TVMDL were the result of administration of CBD containing products.
While the oral LD50 of THC in dogs is estimated to be more than 3 g/kg3, dogs have more cannabinoid receptors in the brain and throughout the body compared to humans, thus intoxication may occur with doses as low as 85 mg/kg.4 According to the ASPCA APCC Database, the most common side effects of marijuana toxicosis are depression, ataxia, and bradycardia. Other signs include agitation, vocalization, vomiting, diarrhea, hypersalivation, tachycardia, hypothermia, mydriasis, urinary incontinence, seizures, and coma.3 THC is readily and rapidly absorbed when inhaled. Absorption is slower and less predictable when ingested. In dogs, onset of clinical signs occurs in minutes if inhaled, and typically within 60 minutes if ingested.1
For more information about TVMDL’s Cannabinoids test visit tvmdl.tamu.edu or call 1.888.646.5623.
1 Brutlag A and Hommerding H. Toxicology of Marijuana, Synthetic Cannabinoids, and Cannabidiol in Dogs and Cats. Vet Clin Small Anim. 2018, 48:1087-1102.
2 Vaughn D, Kulpa J and Paulionis L. Preliminary Investigation of the Safety of Escalating Cannabinoid Doses in Healthy Dogs. Front Vet Sci. 2020, 7:51.
3 Fitzgeral KT, Bronstein AC and Newquist KL. Marijuana Poisoning. Topics in Compan An Med. 2013, 28:8-12.
4 Spiller K. Lost in the weed: Marijuana toxicosis in the age of legalization. VetBloom, 6 June 2017, http://blog.vetbloom.com/ecc/marijuana-toxicosis/.
5 Donaldson C. Marijuana exposure in animals. Toxicology Brief. 2002, 437-439.