Researchers analysing multi-year data from over 47,000 dogs found that those receiving CBD supplements consistently showed less intense aggressive behaviours as they aged, compared to dogs not given the product. The findings represent the largest comprehensive assessment of CBD use in companion animals conducted to date.
“Dogs with consistent CBD use showed a decline in the intensity of aggressive behaviours over time compared to a more steady trend among non-use dogs,” according to the study published in Frontiers in Veterinary Science.
The research, conducted using data from the Dog Aging Project – a community science initiative tracking pet health across the United States – examined owner reports on CBD and hemp supplement use between 2019 and 2023.
Dogs receiving CBD tended to be older, averaging three years older than those not given the supplements. The study found that 7.3 per cent of companion dogs in the US have been given CBD or hemp products at some point, with older animals and those with specific health conditions more likely to receive them.
Dogs with dementia showed the highest prevalence of CBD use at 18.2 per cent, followed by those with osteoarthritis (12.5 per cent) and cancer (10 per cent). After controlling for various factors, seven health conditions were significantly associated with CBD use: dementia, osteoarthritis, epilepsy, hip dysplasia, cancer, chronic diarrhoea, and gastrointestinal disorders.
Male dogs were nine per cent more likely than females to receive CBD supplements, though researchers noted the reasons remain unclear.
CBD use was notably higher in states where medical cannabis is legalised for human use, suggesting owner perceptions of cannabis benefits influence their decisions about pet supplements. The prevalence of CBD use ranged from 1.6 per cent in Iowa to 9.7 per cent in Hawaii.
“Cannabidiol use tended to be higher in states with legalized medical cannabis,” the researchers said, indicating that public perception and accessibility drive pet owners’ willingness to explore these products.
The most striking finding concerned aggression. Dogs given CBD initially showed higher-than-average aggression levels compared to non-users, suggesting owners began supplements partly in response to aggressive behaviour. Over time, however, these dogs displayed below-average aggression relative to control animals.
The same pattern appeared in secondary measures – reactions to unfamiliar circumstances and reactions to other animals – though no similar improvements emerged for anxiety, agitation, or fear-related behaviours.
“Most canine aggression is related to underlying stress or anxiety – a fight or flight response that kicks in,” said Dr Julia Albright, an associate professor at the University of Tennessee College of Veterinary Medicine. “It is unclear why only aggression but not other types of anxious or agitated behaviours seemed to be improved with CBD treatment.”
The study does have several limitations. It relies entirely on owner-reported data without objective measurements of health conditions or behaviour. Researchers lacked information on CBD dosage, formulation, administration method, or product quality, and were concerned that the data used may also have been subjected to owners’ bias – all factors that could influence outcomes.
“At this point, we do not have a complete picture about the behavioural treatment plan,” Dr Albright cautioned. The study participants also skewed towards older, wealthier populations than the general US demographic, potentially limiting the findings’ broader applicability.
The researchers emphasised that further randomised clinical trials are needed to establish whether CBD’s effects on aggression are direct or result from concurrent training or other medications owners may have implemented.
