CBD is not automatically harmful to a healthy dog's liver, but it is not proven safe for dogs with liver disease or abnormal liver tests. In one six-month study, healthy dogs received 4 mg of CBD per kilogram of body weight each day, and more than half developed a temporary increase in alkaline phosphatase, or ALP. A veterinarian should approve CBD and decide whether liver monitoring is needed, especially when a dog has liver disease or takes other medication.
CBD and a Dog's Liver: at a Glance
| Situation | Practical answer |
|---|---|
| Healthy dog using CBD occasionally | It may be tolerated, but safety is not guaranteed |
| Daily or long-term CBD use | Requires veterinary supervision and liver monitoring |
| Existing liver disease or abnormal liver enzymes | Do not start CBD without the veterinarian managing the condition |
| CBD used with seizure, pain or other medication | Ask the veterinarian to review possible drug interactions |
| Product containing THC | Avoid it. THC can cause toxic effects in dogs |
| Vomiting, jaundice, tremors or seizures after use | Contact a veterinarian or emergency animal hospital immediately |
Can CBD Cause Liver Damage in Dogs?
Research in healthy dogs has not shown that standard CBD doses cause liver failure, but it has shown changes in liver-related blood tests. The most consistent finding is an increase in ALP.
In the six-month controlled study, healthy dogs received 4 mg/kg of CBD daily. More than half of the CBD-treated dogs developed a temporary ALP increase. ALT, AST, GGT, bilirubin and bile acids did not show clinically significant changes. The researchers concluded that the dogs tolerated the product but said the ALP increase needed careful interpretation.
In a separate nine-month study, healthy dogs received 5 or 10 mg/kg of CBD each day. Both doses increased ALP. The 10 mg/kg dose produced more liver-enzyme changes, but the study did not find clear evidence of liver injury from the wider liver panel.
A clinical epilepsy study used 9 mg/kg/day. Dogs receiving CBD had substantially higher ALP activity and a statistically significant increase in ALT compared with dogs receiving placebo. This does not show that every dog will develop liver damage, but it is a reason to treat higher-dose and long-term use cautiously.
What Does a High ALP Result Mean?
A high ALP result does not by itself show that CBD has damaged the liver. ALP is less specific for liver-cell injury than ALT. It can come from the liver, bone or other sources.
A veterinarian may interpret ALP alongside:
- ALT and AST
- GGT
- Bilirubin
- Albumin and cholesterol
- Pre- and post-meal bile acids
- The dog's symptoms and physical examination
- Other medicines, including corticosteroids and anticonvulsants
A rising ALP still matters. It can make future blood tests harder to interpret, particularly if ALT, bilirubin or bile acids are also abnormal.
Is CBD Safe for a Dog That Already Has Liver Disease?
CBD should not be given to a dog with diagnosed liver disease unless the treating veterinarian specifically recommends it.
Most controlled CBD safety studies involved clinically healthy dogs. They do not establish that CBD is safe for dogs with chronic hepatitis, copper-associated liver disease, a portosystemic shunt, gallbladder disease, jaundice or reduced liver function. The liver processes CBD, and liver disease can change how a dog processes medicines and supplements.
Veterinary advice is needed before CBD is considered for a dog with:
- Elevated ALT, ALP, AST, GGT or bilirubin
- Abnormal bile-acid results
- A history of hepatitis or liver failure
- Gallbladder disease
- Current treatment with seizure, pain, cancer, steroid or sedative medication
Can CBD Interact With a Dog's Medication?
Yes. CBD may affect how some medicines are processed, although the effect of many such interactions in dogs is still uncertain.
CBD is metabolized through liver enzymes in the canine cytochrome P450 system. Laboratory research using canine liver tissue found that CBD and CBDA can inhibit pathways involved in the metabolism of certain drugs, including tramadol. These findings show a possible interaction, but laboratory results do not predict the exact effect in every dog.
A veterinarian should review CBD use carefully when a dog takes:
- Phenobarbital or other anticonvulsants
- Tramadol or other pain medicines
- Sedatives
- Corticosteroids
- Chemotherapy
- Multiple prescription medicines
Do not reduce, stop or increase a prescription medicine because of CBD without veterinary instructions.
Is CBD Oil the Same as Hemp Seed Oil?
No. Hemp seed oil and CBD oil are different products.
- CBD oil contains cannabidiol extracted from cannabis or hemp.
- Hemp seed oil is pressed from hemp seeds and naturally contains little to no CBD.
- Full-spectrum hemp extracts may contain other cannabinoids, including trace THC.
- THC is a different cannabinoid and can cause toxic effects in dogs.
The U.S. Food and Drug Administration has not approved cannabis for any use in animals. It also says it cannot ensure the safety or effectiveness of cannabis products marketed for pets. Product concentration and purity can vary, so a label should not be treated as equivalent to a veterinary prescription.
How to Use CBD More Cautiously if a Veterinarian Approves It
If a veterinarian decides CBD is reasonable for a particular dog:
- Obtain baseline bloodwork before starting, especially if use will be daily.
- Give the veterinarian the exact product label, concentration and certificate of analysis, if available.
- Avoid products containing THC or products with undisclosed ingredients.
- Do not combine CBD with other supplements or medicines without checking first.
- Use the veterinarian's dose and follow-up schedule instead of copying a dose from an online product label.
- Repeat liver testing as recommended, particularly during long-term use or when the dog has liver risk factors.
Stop CBD and contact the veterinarian if liver enzymes rise substantially or the dog develops new symptoms.
Warning Signs After Giving CBD
Contact a veterinarian promptly if a dog develops:
- Repeated vomiting or diarrhea
- Refusal to eat
- Marked lethargy or weakness
- Yellow gums, skin or whites of the eyes
- Increased thirst or urination
- Dark urine or unusual bleeding
- Loss of coordination
- Excessive drooling
- Tremors, agitation or seizures
FDA guidance lists lethargy, depression, drooling, vomiting, agitation, tremors and convulsions among possible adverse signs after cannabis exposure.
Bottom Line
Before giving CBD, have the treating veterinarian review the product, dose, other medicines and recent liver results. Daily use, higher doses and any history of liver disease call for closer monitoring.