CBD is reported to have low bioavailability in humans and dogs and also goes through a high first-past effect in the liver. To address these challenges, CBD is often administered in oil-based formulations. The liver metabolizes CBD and inhibits several cytochrome p450 isoenzymes raising the concern for potential drug interactions. McGrath et al. initially reported on adverse effects associated with CBD in healthy dogs.
Elevations in alkaline phosphatase enzyme (ALP) were noted in over a 1/3 of the dogs with no evidence of hepatotoxicity based on normal fasting and post-prandial bile acids, so the study concluded that CBD was well tolerated in dogs.
Also in a study conducted by McGrath et al., adverse effects associated with CBD were observed in healthy dogs. They divided 30 healthy Beagles into three groups and administered CBD in different forms – oral capsule, transdermal cream, or oral oil suspension – at doses ranging from 10 to 20 mg/kg/day over a six-week period. Interestingly, all the dogs in the study developed diarrhea, but it was successfully treated with metronidazole therapy.
Additionally, some dogs showed elevated levels of alkaline phosphatase enzyme (ALP), but there was no evidence of liver damage based on normal fasting and post-prandial bile acids. Despite this, the study again concluded that CBD was well tolerated by dogs.
In a follow-up study by the same researchers (McGrath et al.,), the effect of CBD was evaluated in conjunction with conventional antiepileptic treatments in dogs with refractory epilepsy. This randomized, controlled clinical trial involved 26 client-owned dogs, who were assigned to either a treatment group or a placebo group for a duration of 12 weeks. We will discuss the findings on CBD for epilipesy in dogs further in the next post.