Pop open any cupboard in a dog owner's kitchen and you'll likely see a bottle of fish oil or salmon oil sitting next to the treats. Some people swear by fish oil, others claim salmon oil is the only way. So, which one really pulls ahead if you want happy joints, a shiny coat, and that extra wag in your dog's tail?
Understanding Omega-3s: The Real Reason We Use Fish and Salmon Oil
Let’s get this clear up front: the big reason everyone’s obsessed with both oils is omega-3 fatty acids, especially EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). These two guys are like superheroes for your dog’s body. They tame inflammation, help the heart tick along nicely, and even play a big role upstairs in the brain. Human and animal studies (like a 2018 veterinary study out of the University of Glasgow) show dogs on omega-3-rich diets see less itchy skin, fewer allergic outbursts, and even walk easier as they age. The best part? Omega-3s aren’t something a dog’s body can just whip up. They have to eat them.
So why these oils? Lots of fish in the sea have omega-3, but cold-water ocean fish (like salmon, sardines, anchovies, and mackerel) have the highest amounts. Fish oil is usually a blend: think of a mix of anchovy, sardine, and mackerel. Salmon oil, as the name gives away, comes from salmon—period.
Now, here’s where numbers get fun. Per teaspoon, salmon oil usually offers slightly higher amounts of DHA, while anchovy-sardine blends (your typical fish oil) usually supply a bit more EPA. Both matter, but some vets argue DHA is especially important for dogs still growing or those with cognitive struggles.
A quick fact: Farmed salmon (which provides most commercial salmon oil) can contain more omega-3 than wild salmon. That sounds great—but there’s more to consider (hold onto that thought for a couple of paragraphs).
All this means if you’re mainly after those omega-3s, both oils do a solid job. The real difference comes with purity, sourcing, and those hidden extras in the bottle.
Fish Oil: The Pros, Cons, and Real Ingredients
Traditional fish oil, the stuff you’ll find in most pet shops, is usually squeezed from those small, fatty fish. Think sardines, anchovies, mackerel, and sometimes herring—all cold-water dwellers. Most brands offer fish oil in liquid form or, less commonly, soft gel capsules you can snip open over your dog’s food.
On the plus side, fish oil often has a milder smell and taste than pure salmon oil, making it easier for some picky dogs. It’s usually richer in EPA, which some experts say packs the bigger punch against joint and skin inflammation.
The blend in fish oil also keeps costs down. A good bottle made from anchovy and sardine won’t break the bank, especially compared to salmon oil, and you’re still getting a huge omega-3 payload. Tested batches from known brands like Grizzly, Zesty Paws, and even supermarket offerings usually show consistent omega-3 content, if you check lab reports and independent reviews out of the UK and EU.
But not all fish oil is sunshine and roses. Because it’s a blend, quality depends on the source of the fish. Oils from polluted waters—think busy North Atlantic shipping lanes—might have more heavy metals (like mercury) or PCBs, unless they’re thoroughly filtered. Clean brands always mention “molecular distillation” or third-party purity testing on the bottle. Don’t spot those claims? Move on. Fish oil also oxidises easily, especially if it’s been sitting on a warm shelf at some generic store. Rancid oil not only smells horrid, it can actually be harmful to your dog’s health.
And here’s a quirky tip: Some fish oil supplements are beefed up with vitamins A and D. Overdose is possible if you use them alongside a diet already rich in fish—so read those labels closely.
Salmon Oil: Pure, Potent, But Not Without Pitfalls
Salmon oil gets its power from, well, salmon. This oil is often thicker, more golden, and—let’s be honest—has that distinct “fishy” aroma that some dogs adore and others… not so much. If your dog’s been eyeing your smoked salmon breakfast, he won't complain about this supplement.
The big selling point here is purity and source. Salmon oil is, no surprise, single-sourced. You know exactly what’s inside. Norwegian and Scottish farmed salmon dominate the market, since they’re raised in controlled environments less likely to result in heavy metal contamination (as long as the farm’s got a good rep). That means fewer worries over mercury, PCBs, or microplastics. Most reputable salmon oil on UK shelves comes from farms with certifications like “Friend of the Sea”. Always look for these certifications or ask the brand questions before you buy.
Salmon oil leans a little heavier on DHA compared to blended fish oils, which sparks lots of interest for owners of puppies (since DHA supports brain and eye development) and seniors (better memory, less canine drift). And some research done at the University of Edinburgh in 2022 found that salmon oil supplementation improved inflammatory skin conditions and helped lower allergy outbreaks in sensitive breeds.
It’s not all benefits, though. Salmon oil tends to cost more—sometimes double the price of equally potent blended fish oil. It also spoils quickly once opened, thanks to those sensitive fats. Make sure you keep it in a dark, cool place, and buy small bottles if you’ve only got one little dog. And, yes, that fishy whiff lingers on food bowls, hands, and sometimes even on your pet’s face for hours.
Farmed salmon does sometimes carry the risk of lower “wild” nutrient diversity, since their diets can be tightly managed compared to wild fish. If wild-caught salmon oil is available, it often has more omega-3 (per independent tests from consumer groups in 2023), but sourcing and sustainability become big concerns. There’s only so much wild salmon to go around, and the ethical price tag can sneak up on you.
So, Which Oil Does Your Dog Need?
This is where things get interesting. If you’re after maximum omega-3 bang for your buck, fish oil blends are usually cheaper and offer bigger bottles with a strong dose of EPA. For picky eaters or small dogs, the milder taste and lighter consistency of fish oil is a big plus—you won’t get that suspicious look at dinner time.
Got a pup with major skin troubles, allergies, or growing puppies with brains that need fuel? You might want to lean toward salmon oil, thanks to the higher DHA, and the extra peace of mind when it comes to purified sourcing—especially from certified Scottish or Norwegian brands. For senior dogs, the gentle anti-inflammatory lift and those cognitive benefits can be worth the slightly fishier taste and the extra cash.
If your household already eats lots of fish (especially oily ones), keep an eye on total omega-3 intake. More is not always better—too much oil can cause diarrhea, greasy stools, or even affect how blood clots. Always start with the lowest recommended dose on the bottle or use your vet’s guidance, particularly if your dog’s on medications or has a wonky liver.
Let’s not forget cats. Both oils are technically safe for kitties (in the proper dosage), but many cat owners notice salmon oil is more readily accepted than the typical fish oil blends. Just don’t get creative with dosing. Cats need less than half the amount a dog weighs.
Make sure to rotate bottles or buy smaller quantities, as both fish and salmon oil will go bad surprisingly fast—sometimes within 30 days of opening. If you get a bottle that leaves a bitter taste or an overwhelming smell, that’s rancid oil. Bin it straight away and start fresh. For extra shelf-life, keep the oil in the fridge after opening and toss it if you notice any thickening or color changes.
Tips for Shopping and Using Fish or Salmon Oil for Your Pet
If you’ve decided to try either supplement, here are some real-world tricks. Don’t buy the cheapest bottle you see at the discount store. Instead, look for oils with a clear omega-3 content (showing EPA and DHA numbers right on the packaging), a recent production date, and some mention of third-party testing for purity. Trusted brands openly share lab analysis, and those in the UK often link to results on their websites.
Buy small bottles—especially at first. Both oils go bad quickly, even in the fridge. For a single medium-sized dog, a 250ml (about 8 ounces) bottle should last around a month. Don’t leave the cap open and always wipe the nozzle after dispensing—bacteria love fatty residue.
You can pour the oil straight over your dog’s food, or—if they turn up their nose—try mixing it with a teaspoon of plain yoghurt or a small bit of wet food. If your pet is a fussy eater, salmon oil usually has the stronger taste hit, while blended fish oil is often milder. Some oils are “flavoured” to hide the fish scent, but that can be a sign of lower quality or masking old stock.
Watch out for reactions. Start slow—a quarter to half-dose for the first week—especially if your dog’s got a sensitive stomach. Loose stools or greasy patches on the coat are signs you’re giving too much, or the oil is going off. Some sensitive breeds, like Bulldogs, Dachshunds, and Pugs, may react to even small changes, so keep an eye open.
And don’t forget, these are fish oil supplements, not miracle cures. If your dog’s got a medical issue—stuff like sudden hair loss, red rashes, or mobility problems—see your vet. The right oils help, but they’re not a substitute for real medical care.
