Key studies on CBD for dogs have found that, over time, proper dosages of CBD can raise liver enzyme levels. Specifically, ALP, an enzyme that often tests higher as a dog's body metabolizes medications, showed higher levels in 55% of dogs studied.
The ALP raise in these dogs was modest, and not considered clinically abnormal or harmful in general and overall liver function remained within normal limits, which is why the study found that long-term daily feeding of cannabidiol is well-tolerated by healthy dogs.
This article explores relationship between CBD and canine liver enzymes, based on the available research and what that means for dog owners considering CBD for their pets.
Let's take a closer look.
Does CBD Raise Liver Enzymes Dangerously in Dogs?
Note: The dogs in all studies mentioned were studied taking weight-based dosages of CBD. More research is needed to understand the effects of large doses of CBD on dogs' liver enzyme levels.
The short answer is no, research into CBD hasn't shown to raise liver enzymes in dogs to dangerous levels, or even levels outside their normal range. That doesn't mean that it couldn't for some dogs, however.
In order to make the most informed decision for your own pet, you'll need to look a little closer.
Dogs who are on medications, have liver issues, or those that have existing health conditions might have different reactions to CBD, because there can be interactions between CBD and different medications.
Understanding Liver Enzymes & How They're Measured
Here is some key context that will help you understand the research findings, and how they relate to your dog's liver health.
- Liver enzyme levels are examined in relation to the dog's baseline before the study.
In canine CBD's most prominent long-term study (referenced above), liver enzymes were measured in relation to what each dog's baseline was before the study. Results are stated in relation to the group's average baseline (e.g. "levels were +15 U/L after week 18").
Every dog has its own baseline level of liver enzyme activity that can be influenced by a number of factors like health and medications. Testing over the course of weeks is a good way to see how a new supplement like CBD influences liver activity in relation to other factors.
- Liver enzyme activity) are measured in units per liter (U/L).
The U/L metric doesn't actually measure how many liver enzymes are in a liter of your dog's blood. Instead, U/L measures how many units of a substance could be broken down by a given liter of blood. This is why it's more accurate to think of enzyme levels as "enzyme activity." Think of it as "this is how intensely my dog's liver is working to metabolize things."
CBD Influences The Enzyme ALP (Alkaline Phosphatase) - What This Means
ALP is an enzyme produced by the bones and liver. Bones produce it during growth or repair, and the liver uses it when processing bile or detoxifying substances like medications and supplements.
Dogs have a normal ALP range of 20-200 U/L. While studies have shown that CBD raises ALP levels modestly, the reported changes were well within the normal range.
Here is the breakdown of canine CBD's landmark study week-by-week as it relates to liver enzyme levels:
- At week 4, the average increase was +8.5 U/L
- At week 10, the average increase was +15.1 U/L
- At week 18, the average increase was +4.7 U/L
- At week 26, the average increase was +6.1 U/L
These changes are highly normal for dogs that are using a new supplement or medication. There is an initial rise, followed by a balancing out of the levels. Additionally, a 4 week wash out period brought ALP levels back to baseline in the dogs studied.
Why Does CBD Cause Canine ALP to Rise?
CBD is metabolized by cytochrome P450 enzymes, a group of enzymes that both humans and dogs use as a key actor in metabolizing substances and detoxifying the body.
The induction (production) of P450 enzymes is known to cause an increase in ALP levels. This is a common occurrence among humans and dogs, it helps to explain why canine ALP levels rise with CBD use, although the exact correlation isn't fully understood.
There's one other interesting finding that partially explains the rise in ALP levels. As we mentioned before, both the bones and liver produce ALP enzymes. The bone's variety is called BALP (bone-specific ALP), a subcategory within the ALP group.
Adult dogs produce BALP when they are growing, healing, or remodeling. In the Frontiers in Veterinary Science (2022) long-term CBD study (Bradley et al.), researchers found that there was a strong positive correlation between ALP and BALP activity.
“The same dogs that had the largest increase in ALP also had the largest increase in BALP. The strong positive correlation between elevations in total ALP and BALP suggests that the rise in total ALP could be, at least partly, a consequence of increased osteoblastic activity, though further research will be required to confirm this directly.” - (Bradley et al.)
This finding indicates that the mild rise in ALP seen with CBD use may reflect normal bone-related enzyme activity rather than liver strain, aligning with the overall observation that the dogs remained healthy throughout the study.
With Proper Dosage, CBD Hasn't Shown to Influence Liver Enzymes Other Than ALP
Of 6 key studies that examined dogs' liver enzyme levels while taking weight-based dosages CBD, none of them found any influence on liver enzymes other than ALP.
The only other enzyme that saw an increase was ALT, which showed a rise in one study when CBD was given in addition to NSAIDs or phenobarbital. In that case, ALT's U/L typically stayed well within its normal range.
What makes this even more important is that none of the other liver-related enzymes changed alongside ALP. Enzymes like ALT, AST, GGT, bilirubin, and bile acids all stayed stable throughout the study. These are the markers that typically show up first if the liver is under stress, so their stability adds weight to the idea that the ALP rise wasn’t a sign of liver trouble.
Instead, the pattern points to a normal metabolic response—something the body adjusts to over time. When CBD was stopped, enzyme levels returned to baseline, showing that the change was temporary and reversible in the dogs studied. In other words, the liver continued doing its job just fine, even as ALP shifted slightly in response to CBD’s metabolism.
Studies for reference: Bradley et al., Frontiers in Veterinary Science (2022); Vaughn et al., American Journal of Veterinary Research (2021); Gamble et al., Frontiers in Veterinary Science (2018); Deabold et al., Animals (2019); Doran et al., American Journal of Veterinary Research (2021); and Talsma et al., Frontiers in Veterinary Science (2024, CBD + NSAID study).
So, Which Dogs Should Avoid CBD?
While CBD is generally well-tolerated by healthy adult dogs, there are a few cases where it’s best to hold off or talk with your vet first.
- Dogs taking other medications: CBD is processed by the same liver enzymes (the cytochrome P450 group) that metabolize many common drugs. Combining CBD with certain medications—especially NSAIDs, anticonvulsants, or steroids—can alter how those drugs are broken down, leading to complications.
- Dogs with existing liver conditions: Because the liver is responsible for metabolizing CBD, dogs with known liver disease or elevated liver enzymes should be monitored closely or avoid CBD altogether unless guided by a veterinarian.
- Very young, pregnant, or nursing dogs: There’s not enough long-term data on CBD use in these groups, so it’s safest to avoid it until more research is available.
- Dogs with unknown health issues: If your dog hasn’t had recent bloodwork or a checkup, it’s a good idea to confirm normal liver and kidney function before introducing CBD.
In short, CBD has shown a strong safety record in healthy dogs, but like any supplement, it’s not a one-size-fits-all solution. When in doubt, loop in your vet—especially if your dog is on medications or managing a chronic condition.
