CBD dosage for dogs by weight: what the veterinary studies used

The published canine CBD studies are small, short, and mostly industry-funded, but they are consistent about one number: 2 mg per kilogram, twice daily. This page lays out what those studies measured, turns the mg-per-kg figures into a weight-band table, and summarizes what AVMA and FDA say. The calculator on this page is a serving-size helper; it is general information, not personalized guidance, and your veterinarian should know about anything you give your dog.

What dose did the veterinary studies use?

The Cornell group first ran a single-dose pharmacokinetic study in 4 beagles at 2 mg/kg and 8 mg/kg. At 2 mg/kg the elimination half-life was a median 4.2 hours, time to peak was 1.5 hours, and peak plasma concentration was 102.3 ng/mL; no side effects were observed (Gamble et al., 2018). The short half-life is why every canine study dosed twice daily rather than once, and why a single evening serving is unlikely to carry into the next day.

The clinical arm enrolled 22 client-owned dogs, of which 16 completed a 10-week crossover of 2 mg/kg twice daily and placebo, 4 weeks each with a 2-week washout. Owners reported no side effects. The study was funded by a pet CBD company, and the authors' conclusion is specific to the dogs they enrolled (Gamble et al., 2018). Nothing in it describes what any product does for any dog, and this page does not either.

A longer study fed 20 healthy dogs 4 mg/kg once daily for 26 weeks against 20 placebo dogs, with health checks at 2, 4, 10, 18 and 26 weeks and a 4-week washout, and concluded that "4 mg CBD/kg BW is well tolerated in clinically healthy dogs" (Bradley et al., 2022). Note the difference: 2 mg/kg twice daily and 4 mg/kg once daily are the same 4 mg/kg per day.

How much is that for a dog of a given weight?

Weight band	Kilograms	Low (0.5 mg/kg)	Mid (1 mg/kg)	Study dose (2 mg/kg)
5 to 15 lb	2.3 to 6.8 kg	1 to 3.5 mg	2.5 to 7 mg	4.5 to 13.5 mg
16 to 30 lb	7.3 to 13.6 kg	3.5 to 7 mg	7 to 13.5 mg	14.5 to 27 mg
31 to 50 lb	14.1 to 22.7 kg	7 to 11.5 mg	14 to 22.5 mg	28 to 45.5 mg
51 to 80 lb	23.1 to 36.3 kg	11.5 to 18 mg	23 to 36.5 mg	46.5 to 72.5 mg
80+ lb	36.3+ kg	18+ mg	36.5+ mg	72.5+ mg

Each cell is one serving. The studies gave two servings a day, 12 hours apart (Gamble et al., 2018; Deabold et al., 2019). The low and mid columns are arithmetic fractions of the study dose, not doses any study tested; they exist because starting below a study dose and stepping up over 1 to 2 weeks lets you watch for the effects below before you reach the full amount. Round to the nearest dropper mark rather than chasing a decimal.

To turn milligrams into a dropper mark, use the product's mg per mL. A 1000 mg bottle in 30 mL is 33.3 mg/mL, so a 20 lb dog at the 1 mg/kg midpoint (9 mg) gets about 0.27 mL, and at the 2 mg/kg study dose (18 mg) about 0.54 mL. Confirm the mg per mL against the product's certificate of analysis; AVMA notes reports that "a substantial portion of products currently available on the market are labelled inaccurately" (AVMA).

What did blood work show in the studies?

The Colorado State trial reported the same signal: dogs on 2.5 mg/kg twice daily for 12 weeks had a significant increase in serum alkaline phosphatase activity, 2 dogs in the CBD group developed ataxia and were withdrawn, and owners reported no adverse behavioral effects (McGrath et al., 2019). The 26-week study found that the ALP rise occurred without changes in ALT, AST, GGT, bilirubin or bile acids, correlated strongly with the bone isoenzyme of ALP (r of about 0.9), and returned to placebo levels after a 4-week washout (Bradley et al., 2022).

Not every study saw it. In the 12-week Cornell safety study, no dog's ALP left the reference range of 5 to 131 U/L; the mean moved from 39 to 61 U/L, which was not statistically significant (p = 0.09), and the authors concluded the supplement "was not detrimental based on CBC or biochemistry values" (Deabold et al., 2019). The most common unwanted effect in that study was loose stool, recorded 44 times across 53 total events (3.3% of observations), with vomiting 6 times.

The practical reading is that ALP is the one lab value a veterinarian is likely to want to see before and during use, that the published rises were not accompanied by other liver markers, and that none of this has been studied in dogs with existing liver findings. Tolerance at very high single doses looks wide: in 20 beagles given up to 10 escalating doses from about 2 to 62 mg/kg, 94.9% of all adverse events were mild and "dogs tolerated dose escalation of the CBD oil well, experiencing only mild AEs" (Vaughn et al., 2020).

What do AVMA and FDA say?

AVMA's page draws the federal line at 0.3% THC by dry weight: above it is marijuana, a Schedule I controlled substance; below it is hemp, descheduled in 2018. It adds that "State laws legalizing marijuana or hemp use in people do not apply to such use in animals," while noting that many states have since passed laws specific to hemp-derived products in animals (AVMA). Whether your veterinarian can discuss or recommend CBD depends on the state; ask directly.

THC is the ingredient to keep away from dogs. ASPCA Animal Poison Control lists marijuana as toxic to dogs, cats and horses, names delta-9-THC as the toxic principle, and lists vomiting, incoordination, sleepiness or excitation, hypersalivation, dilated pupils and low body temperature among the clinical signs (ASPCA). A canine CBD product should carry a certificate of analysis showing THC non-detect at a stated limit of quantitation, and dogs have no business near human THC gummies.

FDA's page also states that adding CBD to animal food is prohibited and that it cannot ensure the safety or effectiveness of unapproved products; AVMA's legal update records that FDA does not intend to address CBD in food for animals (FDA; AVMA). That is the regulatory backdrop for every pet CBD product sold today, including the ones on this site.

How should you start and what should you watch?

Keep a short log: date, mg given, with food or not, and one line on stool, appetite, energy and coordination. Loose stool and vomiting were the most frequent events in the 12-week safety study (Deabold et al., 2019); ataxia led to 2 withdrawals in the Colorado State trial (McGrath et al., 2019). Any of those is a reason to drop back a step or stop and call your veterinarian, as is any sign on the FDA or ASPCA lists above.

Tell your veterinarian before you start, not after, and ask whether a baseline ALP is worth running given the published pattern (Bradley et al., 2022). If your dog takes any prescription drug, the same enzyme-interaction questions that apply to people apply here, and the veterinary literature on that is thinner still.

This page is general information, not personalized guidance. FDA has not evaluated these statements.