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How Many MG Of Fish Oil Should You Give Your Dog?

Written by FOTP Team


dog jumping high

Fish oil is famous for lubricating the old joints – but did you know it can also protect your dog against diabetes, cancer, and stress?  In this article we’ll cover the benefits and dosage (how many MG your dog needs for the best effects).  Read on to find out all about this wonder-ingredient...and why you should think about popping some too!

Why Fish Oil?

There are several Omega-3s: 

  • EPA (eicosapentaenoic acid) 
  • DHA (docosahexaenoic acid) 
  • Alpha Lipoic Acid (ALA)  

EPA and DHA are the fatty acids which can prevent inflammation – and that covers things like skin allergies and eczema as well as kidney disease, bowel disease, heart disease, and arthritis.  Fish oil is rich in these amazing fatty acids, so it’s very popular as a supplement for dogs (as well as humans).

How Can Fish Oil Help My Dog?

Fish oil is a natural anti-inflammatory, which is beneficial for lots of reasons – equipping your canine to fight off allergies, disease and even cancer.  In dogs, fish oil is particularly recommended for:

  • Treating arthritis and protecting against degradation of cartilage  
  • Treating hyperlipidaemia
  • Preventing epileptic seizures

(In humans, fish oil offers a range of similar benefits – did you know it is even recommended as part of a healthy diet to counter depression? )

Perhaps its most famous use is helping to ward off arthritis.  And while fish oil is often introduced for older dogs, you won’t regret starting early.  Give it to younger dogs to help them build resilience and prevent inflammation in their joints, especially if they work and play hard – it will reduce their risk of developing arthritis later on. 


Fish oil is not suitable for dogs who are already taking medication such as anti-coagulants and anti-inflammatories.  If your dog’s on any regular medication, diabetic, pregnant, or nursing, check with your vet before trying a new supplement. 

How Many MG of Fish Oil Should I Give My Dog?

If you’re just starting out, the rules are the same when you’re introducing any new food.  Give your dog a small amount to test their response.  They might not get along with fish oil and that’s okay – there are alternatives!

So, how much fish oil will you want to give your dog?  

Here’s how that works out for typical breed weights:

  • Great Dane (50kg) = 3,750mg – 5,000mg
  • Labrador (23kg) =    1,725mg – 2,300mg
  • French Bulldog (10kg) = 750mg – 1,000mg
  • Shih Tzu (6kg) = 450mg – 600mg

Should you dish out their serving at breakfast or supper?  According to research, it doesn’t matter what time of day you give fish oil to your dog.  It IS, however, a good idea to give it with their food.  That’s because fatty food will help to improve the absorption of fish oil.  

Does Fish Oil Cause Any Side Effects In Dogs?

Fish oil can cause gastrointestinal upset – so your dog might have some vomiting or diarrhoea.  If your dog experiences this at first, you could try (a) dividing their dosage to feed a smaller amount more frequently and (b) giving fish oil with their food (not separately).

Other side effects are uncommon, and fish oil is generally considered low-risk.  But some serious side effects could include:

  • Weight gain
  • Insulin sensitivity
  • Glycemic control
  • Altered immune function
  • Slower wound-healing

As always, if your dog experiences anything unusual, you should head down to your veterinarian to check things out. 

What Fish Oil Is Best For Dogs?

It’s really important to buy good quality fish oil or supplements.  That’s because disreputable companies sell fish oil which has not been carefully sourced or treated, and can be toxic due to metal contamination.  

When you buy your fish oil, take care to store it properly.  Fish oil should be kept in a cool, dark place that isn’t in direct sunlight.  Some oils should be kept in the fridge – always check the dates and instructions on the jar.

Is Krill Oil Better Than Fish Oil?

Recently there’s been more interest in krill oil; one study used a test group of Alaskan Huskies who were fed either krill oil or fish oil.  The dogs in the krill group experienced a raise in Omega-3 levels from 3.9 to 6.3%, significantly more than the dogs in the fish oil group.  

One reason that krill oil works well is that it also contains a powerful antioxidant (astaxanthin), which stabilises the fatty acids so they can be better-absorbed.  

When we developed our recipe for The One, we picked krill oil to supply the Omega-3s – it’s less likely to be contaminated with toxins and it has shown better results than fish oil for conditions like arthritis.  So we add whole krill to our supplement, delivering Omega-3s without the nasties. 

Does Fish Oil Contain Mercury?

Man-made pollution has affected the ocean and everything living in it.  So we’re now living with fish contaminated with our own gruesome toxins.  Because fish contains mercury, lead, and polychlorinated biphenyls (PCBs), it’s not recommended for frequent consumption.  However, recent testing has shown that fish oil doesn’t contain the same levels as fresh fish.  It’s carefully filtered to remove contaminants, so fish oil supplements are safer to ingest.

Does Krill Oil Contain Mercury, Too?

Krill are tiny crustaceans.  They’re near the bottom of the ocean’s food chain, and studies show that krill have far lower levels of contaminants like mercury (compared with fish oil). 

How Long Does Fish Oil Take To Work?

Omega-3 penetrates the cells in its own time – allow around 2 months before you can see any difference in your dog’s health.