Dose off the EPA plus DHA, per kilogram
The number that matters is the combined EPA and DHA a cat gets each day, scaled to its weight. A capsule labelled "1000 mg fish oil" may only carry 150 to 300 mg of actual EPA plus DHA, so always work from the active figure on the label.
Dose by goal and body weight
| Goal | EPA+DHA per kg/day | 5 kg cat | 10 kg cat |
|---|---|---|---|
| General maintenance | 30–40 mg | 150–200 mg | 300–400 mg |
| Heart health | 40–50 mg | 200–250 mg | 400–500 mg |
| Joints / arthritis | 50–75 mg | 250–375 mg | 500–750 mg |
| Kidney disease (CKD) | 112–120 mg | 560–600 mg | 1120–1200 mg |
| Safe ceiling | 75 mg | 375 mg | 750 mg |
All figures are total daily EPA plus DHA. The therapeutic kidney dose sits above the general ceiling on purpose and should only be given under veterinary supervision. This is general information, not veterinary advice.
Giving it safely
- Start low. Begin at about half the target and build up over 1 to 2 weeks; if the cat gets loose stools, drop the dose by a quarter.
- Count the diet. Many cat foods already contain some omega-3, so factor that in rather than adding the full dose on top.
- Mind the calories. Fish oil is about 9 kcal per gram, so trim food slightly for cats watching their weight.
- Pause before surgery. Because it can slow clotting, stop fish oil ahead of any procedure and avoid combining it with blood-thinning medication. Confirm with your vet.
Common questions
How much fish oil should I give my cat?
Dose by the combined EPA plus DHA, not the oil volume. General health maintenance is about 30 to 40 mg per kg of body weight per day, so a 5 kg cat gets roughly 150 to 200 mg daily. Higher therapeutic doses exist for specific conditions but should be confirmed with a vet.
Can a cat have too much fish oil?
Yes. Above about 75 mg of EPA plus DHA per kg per day, cats can develop diarrhoea, poor blood clotting, easy bruising and a fishy odour. Stay under that ceiling unless a vet has set a higher dose and is monitoring your cat.
Do I dose by the milligrams of oil or the EPA and DHA?
By the EPA and DHA. A 1000 mg fish oil capsule often contains only 150 to 300 mg of actual EPA plus DHA, and this varies a lot by brand. Read the label and dose off the active omega-3 figure, not the total oil weight.
