L-Carnitine in dog and cat food

Is it OK for dogs and cats?

Dogs

No known concern at the amounts used in dog foods; dogs make their own L-carnitine, and it is commonly added to weight-loss diets. A link between low carnitine and heart disease (DCM) in dogs has been reported only in small case studies, and in those dogs vets give L-carnitine as a treatment.

Cats

No known concern at the amounts used in cat foods. Studies in overweight cats found that added L-carnitine helped fat burning while conserving lean body mass, and vets give it as part of treatment for cats with fatty liver disease (hepatic lipidosis).

How settled this is: No known concern at the amounts used in complete foods

What L-Carnitine is

L-carnitine is a water-soluble compound made in the body. Merck describes it as a conditionally essential, vitamin-like nutrient synthesised in the liver and kidneys from SAMe (which comes from methionine), lysine, vitamin C, vitamin B6 and iron. The L form should be used for supplementation: a review of canine heart disease notes that D-carnitine can interfere with the body's use of L-carnitine.

Why it is in pet food

Merck notes that most diets formulated for weight loss in dogs and cats include supplemental L-carnitine, along with more protein and fibre. In overweight cats, three investigational studies summarised by Merck found that added L-carnitine helped fatty acid oxidation while conserving lean body mass. FEDIAF's nutrient tables for complete foods do not list L-carnitine, so there is no FEDIAF minimum for foods to meet.

What it does in the food

Carnitine moves long-chain fatty acids into the mitochondria, where they are broken down (beta-oxidation) for energy; a review of canine heart disease notes that roughly 60% of the heart's energy comes from this route. The body builds it from lysine and methionine. A feline review describes higher carnitine needs when cats mobilise large amounts of body fat, as in fasting or hepatic lipidosis; in cats fed 25% of their energy needs, supplemental carnitine kept liver fat build-up minimal. Merck notes that cats' natural prey contains 150-3,000 mg L-carnitine per kg of tissue, substantially more than many cat foods.

Safety and limits

The sources cited here do not report harm from L-carnitine at the amounts used in complete foods, and FEDIAF's guidelines list no maximum for it. Treatment doses are set by vets for specific conditions: Merck recommends 250-500 mg per cat daily for cats with hepatic lipidosis, and a review of canine DCM cites 50-100 mg/kg every 8 hours for dogs with systemic carnitine deficiency. Merck also notes that a study of many over-the-counter L-carnitine products found a lack of bioavailability. For dogs, the review lists carnitine deficiency among nutritional factors in DCM but says only small case studies have reported it, such as two Boxer littermates with DCM that improved when given L-carnitine. The same review describes a separate trial in which Cocker Spaniels with DCM and low plasma taurine improved when given taurine and L-carnitine.

What depends on the amount and the recipe

Dogs and cats normally make their own L-carnitine, so whether added carnitine matters depends on the situation: it is most discussed for weight-loss diets, for cats mobilising body fat quickly (fasting, rapid weight loss, hepatic lipidosis), and for some dogs with carnitine-responsive heart disease. In dogs, the canine review suggests very low-protein diets may supply fewer precursors for carnitine and taurine synthesis. The form matters too: the bioavailability of L-carnitine salts and esters can vary, and D-carnitine should not be used.

Not the same as

• D-carnitine (or DL-carnitine) — Not the form to use for supplementation; D-carnitine can interfere with the body's use of L-carnitine.
• Acetyl-L-carnitine and L-carnitine salts (e.g. L-carnitine L-tartrate) — Related forms that supply carnitine. The canine review notes bioavailability varies by form: in one piglet study, salts were similar to free L-carnitine and esters were lowest.
• Taurine — A different nutrient often discussed alongside carnitine in heart disease; cats must get taurine from food.

Sources

1. Feline Hepatic Lipidosis (full review Aug 2023, updated Jun 2025) — Merck Veterinary Manual, 2025. L-carnitine is a conditionally essential vitamin-like nutrient made in liver and kidneys from SAMe, lysine, vitamin C, B6 and iron; three studies in overweight cats show benefit for fatty acid oxidation while conserving lean mass; prey contains 150-3,000 mg/kg; dosing 250-500 mg/cat/day in hepatic lipidosis; many OTC products lacked bioavailability.
2. Nutrition in Disease Management in Small Animals (full review Nov 2023, updated Jun 2025) — Merck Veterinary Manual, 2025. Most diets formulated for weight loss in dogs and cats include more protein and fibre and supplemental L-carnitine.
3. Verbrugghe A, Bakovic M. Peculiarities of One-Carbon Metabolism in the Strict Carnivorous Cat and the Role in Feline Hepatic Lipidosis. Nutrients 5(7):2811-2835 — Nutrients (MDPI), via PubMed Central, 2013. SAMe is a precursor of L-carnitine, a conditionally essential amine made in the liver that carries long-chain fatty acids into mitochondria; relative carnitine deficiency in feline hepatic lipidosis; minimal liver lipid in cats at 25% of energy needs given carnitine; effect on fatty acid oxidation in overweight cats losing weight; cats need dietary taurine.
4. McCauley SR et al. Review of canine dilated cardiomyopathy in the wake of diet-associated concerns. J Anim Sci 98(6):skaa155 (authors at BSM Partners and The Heart Vet) — Journal of Animal Science (Oxford University Press), via PubMed Central, 2020. Carnitine is water-soluble, made in the liver, precursors lysine and methionine, transports long-chain fatty acids; ~60% of heart energy from beta-oxidation; only small case studies link carnitine deficiency to canine DCM (e.g. Boxer littermates); MUST trial Cocker Spaniels with low taurine improved on taurine and L-carnitine; dose 50-100 mg/kg q8h for systemic deficiency; D-carnitine interferes; bioavailability of salts and esters varies; low-protein diets may lack carnitine and taurine precursors.
5. Nutritional Guidelines for Complete and Complementary Pet Food for Cats and Dogs (September 2025) — FEDIAF (European Pet Food Industry Federation), 2025. The recommended nutrient tables for complete dog and cat foods list no minimum or maximum for L-carnitine.

Checked against these sources on 2026-10-15. Definitions are in our own words. This is a reading aid, not veterinary advice: a vet who knows your animal comes first.