Sardines are a good whole food source of omega 3s for dogs, and the right can is the one packed in water with no salt added. Feed them by size, from a quarter of a sardine for a toy breed to two or three for a large dog, a few times a week rather than daily. This post covers which can to buy, how many to feed, the mercury question (the answer is reassuring), and where sardines fall short of a measured fish oil, so you know when the two dollar can is enough and when it is not.
Are sardines good for dogs?
Yes, with the right can and the right amount. Sardines are small, whole fish, so a dog eating one gets the meat, the soft bones, and the fat, and the fat is the point. The NIH Office of Dietary Supplements lists a 3 ounce serving of canned sardines (its table entry is sardines in tomato sauce, drained) at 0.74 g of DHA and 0.45 g of EPA, which together is a little under 1.2 g of the two omega 3s that matter for dogs.1 That puts a single small can in the same range as a decent dose of fish oil for a mid sized dog, delivered as food instead of a pump. The bones also bring calcium, and because the fish are small and soft after canning, they are generally safe to eat whole, unlike cooked bones from a larger fish.
Why do people care about omega 3s in the first place? The Merck Veterinary Manual's osteoarthritis chapter reports that EPA supplementation and EPA rich diets have been shown to improve gait and mobility in arthritic dogs and to have an NSAID sparing effect, and its skin chapter notes essential fatty acids may help itchy dogs when used long term, with roughly one in five allergic dogs showing some improvement.23 Sardines are one way to get those fatty acids into a dog. Not the most precise way, but a cheap and real one.
Which can: in water, no salt added
Read the label. You want sardines packed in water with no salt added, and nothing else in the ingredient list. Skip sardines in oil (extra fat and calories your dog does not need), in tomato sauce, in mustard, or with chili, garlic, or onion. The ASPCA warns that excessive salt intake can produce increased thirst and urination and sometimes abnormal electrolytes in the blood, and onion and garlic are on its list of foods to avoid entirely.4 Most "in water" cans still contain some salt, so "no salt added" is the phrase to look for, and if you can only find lightly salted, drain and rinse them.
Fresh sardines, baked plain with no seasoning, also work and are lower in sodium. They are harder to find and more work. Frozen raw sardines are sold for pets; we do not sell frozen raw and this post does not cover it.
How many sardines can a dog have?
Sardines are fatty, so the portion has to respect both the treat rule (extras under 10% of daily calories) and your dog's stomach. A workable guide:
- Under 15 pounds: a quarter to half a sardine, two or three times a week.
- 15 to 40 pounds: half to one sardine, two or three times a week.
- 40 to 80 pounds: one or two sardines, two or three times a week.
- Over 80 pounds: two or three sardines, two or three times a week.
Start at the low end and watch the stool for a week. Fish oil in any form can loosen stools if the dose jumps, and Merck notes large doses of essential fatty acids may also cause weight gain or diarrhea.3 Mash them into the food rather than feeding them as a separate treat, and if you feed sardines, cut back on other fatty extras that day. Dogs with a history of pancreatitis or on a low fat diet should not get sardines without a vet's say so.
Mercury: not a problem with sardines
This is the question owners ask most, and the answer is good. Sardines are small, short lived, and low on the food chain, which is exactly the profile of a low mercury fish. The FDA's monitoring data puts sardines at a mean of 0.013 ppm mercury. For comparison, the same table lists canned light tuna at 0.126 ppm, canned albacore at 0.350 ppm, and swordfish at 0.995 ppm.5 At a few sardines a week, mercury is not a reason to hesitate.
Where sardines fall short
Three honest limits. First, precision. A can does not tell you EPA and DHA per fish, and fish vary. If your vet has given you a target omega 3 dose for a joint or skin problem, a fish oil that states milligrams of EPA and DHA per pump is the tool for hitting it. Our fish oil dosage guide explains how to read those labels, and the omega 3 products in our supplements collection are ones that print the numbers. Second, calories. Sardines are dense, and a small dog fed a whole can is getting a large share of the day's food in fat. Third, smell. Your kitchen, the dog's breath, and the trash can will all report back. Salmon has a milder reputation, and we compare the two in can dogs eat salmon.
One more: sardines are a topper, not a fix for a poor food. They add fat, protein, and omega 3s to a diet that is already complete and balanced. Our anti inflammatory diet for dogs guide puts them in context with the rest of the bowl.
When to call the vet
Call if your dog vomits or has diarrhea that lasts more than a day after eating sardines, if a small dog gags or seems uncomfortable after swallowing a whole fish, or if your dog has ever had pancreatitis and you want to add fatty fish at all. Also ask before adding sardines to a dog on a prescription diet, since the fat and calcium can change what that diet was designed to do. For a healthy dog on the amounts above, the likely worst case is a soft stool and a fishy kiss.
Sources
- National Institutes of Health, Office of Dietary Supplements, "Omega-3 Fatty Acids: Fact Sheet for Health Professionals," 2026. ods.od.nih.gov
- Merck Veterinary Manual, "Osteoarthritis in Dogs and Cats," reviewed 2024, updated 2025. merckvetmanual.com
- Merck Veterinary Manual, "Essential Fatty Acids for Integumentary Disease in Animals." merckvetmanual.com
- ASPCA Animal Poison Control Center, "People Foods to Avoid Feeding Your Pets." aspca.org
- U.S. Food and Drug Administration, "Mercury Levels in Commercial Fish and Shellfish (1990-2012)." fda.gov