CBD for cats: absorbed 7 times less than in dogs

Five published studies have given CBD to cats, all of them healthy, and three compared it with a placebo. No study has included sick cats. Groups are small, and pet-product manufacturers funded at least four of the studies: Ellevet Sciences, Canopy Growth and Mars Petcare.

ALT (alanine aminotransferase) is a liver enzyme. When a blood test shows it rising, the liver is under strain, which is why vets monitor it through any long course of treatment.

In the Deabold trial, 8 dogs and 8 cats received the same product at the same dose. Peak blood CBD reached 301 ng/mL in the dogs and 43 ng/mL in the cats. Total exposure over the day, given by the area under the curve, came to 1,297 against 164 ng·h/mL.

Poorer absorption is no reason to raise the dose, for three reasons. The first is that the form of the product makes a large difference. Depending on the study, a 2025 review in the Journal of Feline Medicine and Surgery reports peaks of 42 ng/mL with a fish-oil base and 465 ng/mL with a paste. Food also counts: at the same dose, fed cats reached 463 ng/mL and fasted cats 269 ng/mL.

The second is metabolism, since cats and humans process cannabinoids through different pathways. The same review describes hydroxylation at positions 6 and 4' in cats, whereas humans mainly produce a derivative hydroxylated at position 7. Cats also clear many phenolic compounds poorly. They lack the UGT1A6 enzyme, inactivated in every member of the cat family, which accounts for their sensitivity to paracetamol. No study has shown that this deficit affects CBD, but it illustrates why data from dogs or humans cannot simply be applied to cats.

The third is the gap between individuals. In the Lyons trial, the coefficient of variation of blood levels went above 100% at some sampling times, so cats on the same dose ended up with very different blood levels.

The effects reported in these healthy cats remained mild. Over twelve weeks and 1,344 observations, the Deabold team recorded 476 episodes of excessive licking (35.4%) and 339 of head shaking (25.2%). In the Kulpa trial, the CBD oil mainly caused drooling and roughly an hour of drowsiness, both of which passed without treatment. The vomiting and diarrhoea seen were attributed to the MCT carrier oil and not to CBD.

The liver needs watching. In the Deabold trial, one cat had ALT above the normal range from start to finish. At four weeks in the first Coltherd trial, ALT in the CBD group was 1.44 times the placebo value. Two cats from that group were withdrawn from the long study for suspected cholangitis, an inflammation of the bile ducts. The 26-week trial found no such difference.

The danger with the most evidence behind it is THC. In the Kulpa trial, oils containing THC produced more neurological effects and behaviour changes than the CBD oil. The 2025 review adds that these effects lasted longer when CBD and THC were combined. Since an oil sold for humans may contain THC up to the legal limit of 0.3%, its measured level matters as much as the CBD dose.

In humans, CBD changes how some medicines act because it slows the liver enzymes that clear them. Our article on CBD and drug interactions explains this mechanism, which nobody has studied in cats. For a cat already on treatment, the vet's opinion counts most of all.

Any CBD product that claims a therapeutic effect for an animal, against pain for example, is a veterinary medicine. Anses points this out and adds that such a product needs an authorisation from Anses or from the European Commission, granted on criteria of quality, safety and efficacy. No veterinary medicine containing CBD is authorised in France.

By way of exception, a vet may prescribe a human medicine when no suitable veterinary medicine exists. This is the "cascade" of article L5143-4 of the French Public Health Code. For pain in dogs and cats, the veterinary medicines agency (ANMV) has stated that authorised medicines exist, which rules out CBD by that route.

For food, the French agriculture ministry's notice of 20 May 2026 calls for CBD foodstuffs intended for humans to be withdrawn, because they have no novel food authorisation. Pet products are outside its scope. Our update on CBD regulation in 2026 explains that regime. Horses also come under racing rules, covered in CBD in equines.

A brand name is not enough information. Your vet will need:

• the cat's weight and age, and any treatment it is on;
• the actual concentration of the product, in mg of CBD per mL;
• the measured Δ⁹-THC level, and confirmation that no other cannabinoid such as HHC is present;
• the excipients: carrier oil, flavourings, sweeteners.

A rough calculation shows why an oil made for humans fits a cat badly. For a 4 kg cat, the lowest dose in the trials, 2 mg/kg, comes to 8 mg. That is 0.16 mL of a 5% oil, under a fifth of a millilitre. The figure is no dosage recommendation. It shows that a few drops more or less change the dose completely.

You can check a product's data on its certificate of analysis. Our guide explains how to read a certificate of analysis, and the laboratory page describes the measurement methods. Dogs have different reference points and limits, set out in our article on CBD for dogs and the veterinary framework.