Cod Liver Oil for Dogs: What You Need to Know

Most of the benefits from cod liver oil come from the omega-3 fatty acids. These beneficial fats have been shown to support healthy cellular function and modulate inflammation, which is a key component of conditions such as heart disease and osteoarthritis of the joints. However, cod liver oil also contains fat-soluble vitamin A and D. In excess amounts, these accumulate in the body and can result in health problems.  

Because of this, most dogs eating a healthy diet should not be given extra vitamin A or D unless a vet recommends it.  

As a result of the risk, there isn’t much direct evidence supporting the use of cod liver oil in dogs. Most research has focused on the benefits of omega-3 fatty acids, which have been singled out for various benefits, including: 

• Joint support: Studies performed in dogs with osteoarthritis showed that omega-3 fatty acids led to significant improvement, better weight-bearing, and lower doses of carprofen (an anti-inflammatory commonly prescribed for joint pain).  
• Skin and coat support: Research has shown that allergy symptoms improved in dogs given fish oil and coat quality improved in dogs given EPA and DHA. 

Oil supplements can cause digestive upset, including nausea, vomiting, and diarrhea. High omega-3 intake can affect platelet function, which could cause excessive bleeding in dogs having surgery. 

The more significant concern involves vitamin toxicity, known as hypervitaminosis. An excess of Vitamins A and D can develop, since fat-soluble vitamins tend to build up when intake is too high.  

Vitamin A toxicity in dogs can cause: 

• Lethargy and weakness 
• Decreased appetite 
• Nausea 
• Dry, peeling skin 
• Tremors or seizures 
• Death 

Vitamin D toxicity in dogs can cause:  

• Depression 
• Vomiting 
• Increased drinking 
• Increased urination 
• Kidney damage 

Give cod liver oil only if your veterinarian recommends it. In most cases when your vet thinks omega-3 fatty acids could help, they’ll choose a product that doesn’t also contain additional fat-soluble vitamins. If your vet does think cod liver oil is a good idea, use the exact product and dosing they recommend. 

If your dog gets into cod liver oil or you accidentally give more than intended, here’s what to do: 

• Call your veterinarian, an emergency hospital, or the Pet Poison Helpline (855-764-7611) right away.  
• Have the bottle nearby so you can provide information about the exact ingredients and vitamin amounts. 
• Don’t wait for signs of toxicity to develop. It’s better to be safe than sorry when it comes to toxicity. 

Not exactly. Cod liver oil is a type of fish oil, but it in addition to omega-3 fatty acids it also contains vitamins A and D.  

Omega-3s have been studied in dogs for joint support, but most studies have looked at fish oil or omega-3 fatty acids rather than cod liver oil. If your vet thinks an omega-3 fatty acid supplement is a good idea, they’ll probably suggest one that doesn’t contain extra vitamins.  

Yes. Oil supplements can cause digestive upset, especially if a dog gets too much or has a sensitive stomach. 

Ask your veterinarian first. Puppies need balanced nutrition, and extra fat-soluble vitamins can cause an imbalance and lead to toxicity.