How Risky Is It To Use Cannabis Around Pets?

When smoking cigarettes was common, there was a lot of misinformation about how harmful secondhand smoke could be. As more data emerged, smoking bans emerged to protect workers, children, and anyone else who may be at risk. This is one of the reasons why cannabis is so regulated: to avoid exposing people to unwanted risks of second-hand smoke. 

States that allow personal consumption typically only do so in private residences, prohibiting public consumption. There is one group that still faces the risks of secondhand smoke without having the ability to make the choice for themselves. Pets are often exposed to their owners’ second-hand smoke, and that is not really good for them. Animals’ threshold for cannabis tolerance is different from humans, and any exposure may be potentially harmful.

Is Cannabis Secondhand Smoke Safer than Tobacco

Multiple studies have been done regarding the harmfulness of secondhand smoke on pets, but most of the data are based on tobacco smoke. 

The Centers for Disease Control and Prevention (CDC) points out that cannabis and tobacco smoke contain many of the same toxins, but in different amounts. [1] In fact, cannabis smoke has a higher concentration of multiple toxic particles, including significant amounts of hydrogen cyanide and more than triple the concentration of ammonia than tobacco. [2] 

These differences may be negligible to humans, but animals have different metabolisms, cardiovascular, and digestive systems. Cannabis appears to be potentially more toxic to the average household pet. [3]

Risky Pleasure 

Pet owners should be concerned with cannabis smoke’s ability to permeate an entire house. One study found the concentration of fine particle matter (PM_2.5) was 4.4 times higher in every room following cannabis smoking compared to tobacco. [4] Fine particles from smoke may lead to heart disease or stroke after extended exposure. [5] This means that even if the cannabis is smoked in a single room, pets anywhere in the house may still be at risk of exposure. 

These data should be assessed with skepticism, though, because while tobacco is linked to cancer, the connection has not been established with cannabis. [6][7] 

Since there is not enough long term data about cannabis exposure in pets, most veterinarians are focused on the short term risks of cannabis consumption.

Secondhand Smoke Risks for Dogs

Cannabis can be toxic for dogs, who are even more at risk than other common pets for two main reasons. Studies show that dogs living in smokers’ houses see higher incidence of allergies, respiratory issues, eye infections, and lung cancer. [8] 

These represent a possible long term risk, but there are multiple short term risks as well.

There is No Smoke Without Fire 

Over the last seven years, the number of dogs overdosing on cannabis has risen almost 450% over the last six years. [9] Anyone who has ever owned a dog knows that their curious nature means that they are prone to eat anything they can find. This means that edibles may not be a safe alternative for dog owners. Moreover big cities have also seen a 300% rise in dogs exposed to cannabis from eating cannabis butts. Even taking your dog for a walk may put them at risk if you are not paying attention. If a dog does consume too much cannabis, there are several signs to watch out for. [11] Smaller doses may lead to the following symptoms: 

• Lethargy;
• Stumbling;
• Agitation;
• Vomiting;
• Heart irregularity;
• Seizures. 

Cats and Cannabis Consumption

Cannabis is also toxic to cats, but the risks are different from dogs. The good news for cat owners is that 96% of veterinary visits due to cannabis exposure come from dogs, not cats. [12] When it comes to secondhand smoke, though, cats face a higher risk. Cat lungs are also sensitive to smoke particles, and one study found that cats exposed to secondhand smoke are three times more likely to develop malignant lymphoma than those who are not. [13] 

The reason cats face a higher risk could be that because they are self-cleaning animals, they could ingest smoke particles trapped in their fur during grooming. [14] 

Signs of cats exposure to cannabis are the following:

• Strange behaviors; 
• Increased vocalizations;
• Loss of coordination;
• Loss of consciousness; 
• Heart palpitations.

Small Pets and the Largest Risk

There is a reason canaries were used as an early warning sign for toxic gas in coal mines: small animals are even more sensitive to toxins in the air. Birds, mice, and rabbits all face higher risks from second-hand smoke than larger pets. [15][16][17] Part of the reason is that birds are more sensitive to airborne toxins, but also it relates to the size of the animals lungs.[18] 

The smaller the lungs, the more they are exposed to smoke because of the surface area to volume ratios. This may help to explain why pets overdosing on cannabis is rising for almost every species. [19] 

References

1. Secondhand Marijuana Smoke | Health Effects | Marijuana | CDC. (n.d.)
2. Ott, W. R., Zhao, T., Cheng, K., Wallace, L., & Hildemann, L. M. (2021). Measuring indoor fine particle concentrations, emission rates, and decay rates from cannabis use in a residence. Atmospheric Environment: X, 10, 100106 
3. Amissah, Richard Quansah, et al. “Prevalence and characteristics of cannabis-induced toxicoses in pets: Results from a survey of veterinarians in North America.” PLoS One 17.4 (2022): e0261909.
4. Ott. W.R., Wallace, L.A., Cheng, K-C, and Hildemann, L.M., “Measuring PM2.5 concentrations from secondhand tobacco vs. marijuana smoke in 9 rooms of a detached 2-story house,” Science of the Total Environment 852 (2022) 158244.
5. Alexeeff, Stacey E., et al. “Long‐term PM2. 5 exposure and risks of ischemic heart disease and stroke events: review and meta‐analysis.” Journal of the American Heart Association 10.1 (2021): e016890.
6. Johnson, Kenneth C., et al. “Active smoking and secondhand smoke increase breast cancer risk: the report of the Canadian Expert Panel on Tobacco Smoke and Breast Cancer Risk (2009).” Tobacco control 20.1 (2011): e2-e2.
7. Melamede, Robert. “Cannabis and tobacco smoke are not equally carcinogenic.” Harm Reduction Journal 2.1 (2005): 1-4.
8. Zierenberg‐Ripoll, A., et al. “Association between environmental factors including second‐hand smoke and primary lung cancer in dogs.” Journal of Small Animal Practice 59.6 (2018): 343-349.
9. Amissah RQ, Vogt NA, Chen C, Urban K, Khokhar J. Prevalence and characteristics of cannabis-induced toxicoses in pets: Results from a survey of veterinarians in North America. PLoS One. 2022 Apr 20;17(4):e0261909. doi: 10.1371/journal.pone.0261909. PMID: 35442991; PMCID: PMC9020701.
10. Calvan, B. C. (2023, May 2). Big-city dog owners are dealing with an epidemic of marijuana butt poisonings as the number of canine cannabis cases surges 300% in 5 years. Fortune Well.
11. Johnstone, G. (2023). Marijuana Poisoning in Dogs. American Kennel Club.
12. Janeczek A, Zawadzki M, Szpot P, Niedzwiedz A. Marijuana intoxication in a cat. Acta Vet Scand. 2018 Jul 11;60(1):44. doi: 10.1186/s13028-018-0398-0. PMID: 29996908; PMCID: PMC6042427.
13. Bertone, Elizabeth R., Laura A. Snyder, and Antony S. Moore. “Environmental tobacco smoke and risk of malignant lymphoma in pet cats.” American journal of epidemiology 156.3 (2002): 268-273.
14. Smith, Victoria Anne, et al. “Hair nicotine concentration measurement in cats and its relationship to owner‐reported environmental tobacco smoke exposure.” Journal of Small Animal Practice 58.1 (2017): 3-9.
15. Hutton, A., Takkouche, S., Irshad, A., & Loutfi, C. (2020). DEVELOPMENT OF BIRD FANCIER’S LUNG AFTER WITHDRAWAL OF SECONDHAND SMOKE. Chest, 158(4), A62.
16. Chen, Chao-Yin, et al. “Short-term secondhand smoke exposure decreases heart rate variability and increases arrhythmia susceptibility in mice.” American Journal of Physiology-Heart and Circulatory Physiology 295.2 (2008): H632-H639.
17. Hutchison, Stuart J., et al. “Secondhand tobacco smoke impairs rabbit pulmonary artery endothelium-dependent relaxation.” Chest 120.6 (2001): 2004-2012.
18. Eschner, K. (2016, December 30). The Story of the Real Canary in the Coal Mine. Smithsonian Magazine.
19. LaMotte, S. (2022, April 20). It’s not just dogs: All sorts of pets are being poisoned by marijuana. CNN.

• Health & Wellness
• Troubleshooting