Omega-3 Fatty Acids (Fish Oil) for Dogs and Cats

Medically Reviewed by Joshua Conrad, PharmD on October 10, 2024
Written by Kathleen Claussen, DVM
4 min read

Omega-3 fatty acids (brand names: Dermapet, Eicosaderm, Welactin, and others) are a dietary supplement for long-term use in dogs and cats. They are also known as fish oil. They are usually used in addition to other medicines to control specific conditions involving inflammation (swelling) of the skin, heart, kidneys, or liver. They can also be used to aid in the treatment of arthritis and neurologic (nerve) issues. In dogs and cats, omega-3 fatty acids help with the control of itching associated with skin diseases such as atopic dermatitis (eczema), seborrhea, and eosinophilic granuloma complex, especially when used in combination with other medicines and treatments.

Essential fatty acids (EFAs) are polyunsaturated fatty acids that are not made by the body. They must be gotten from external sources, usually foods. EFAs help with normal cell function. Omega-3 fatty acids are EFAs. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are common omega-3 fatty acids found in fish oil.

Dietary supplements are monitored by the FDA in the U.S., but they are not regulated under the same rules as food and medicines are. The FDA does not approve dietary supplements for safety or effectiveness, nor does the FDA approve the product label. These measures are the responsibility of the supplement company. It is important to discuss dietary supplements with your veterinarian. They can help you with product selection and dosing. 

Omega-3 fatty acids must be given long-term (weeks to months) before you can tell if they are helping your pet. Fish oil used with antihistamines may have a greater effect when used together than when used separately for itching and allergic skin conditions.

Omega-3 fatty acids are given by mouth every 24 hours as a capsule or oral liquid. The oral liquid must be measured carefully. Omega-3 fatty acids can be given with or without food.  

There are many products available without a prescription from your veterinarian or over-the-counter.  It is best to discuss your options with your veterinarian since content varies widely between products.  Look for a product that also has vitamin E as an ingredient and that is certified free of heavy metals or other contaminants.

Always follow your veterinarian’s directions for giving medicines to animals. Tell your veterinarian about any medicines, vitamins, supplements, or herbal therapies that you are giving your pet. Talk to your veterinarian before stopping any pet medicines.  

  • Omega-3 fatty acids are well tolerated by dogs and cats.
  • Omega-3 fatty acids have few side effects.
  • Omega-3 fatty acids can be helpful for many inflammatory issues.
  • Omega-3 fatty acids are available without a prescription.

You and your veterinarian should monitor your pet for improvement of their condition as well as for side effects of fish oils. No routine blood tests are needed.

Do not use omega-3 fatty acids in animals that are allergic to it or in animals that are pregnant. Be careful using omega-3 fatty acids in animals that have bleeding disorders, have long-term diarrhea, or are eating a prescription diet with fatty acids already in the food.

Side effects with omega-3 fatty acids are uncommon. They are usually well tolerated by dogs and cats.  The most common side effects of omega-3 fatty acids usually occur at higher doses and include:

  • Vomiting 
  • Diarrhea
  • Belching

Other, less common side effects include:

  • Tiredness
  • Impaired wound healing
  • More itching
  • Increased risk of bleeding

If you suspect that your pet is having a serious side effect or may have been overdosed, call your veterinary clinic immediately. If it is outside of regular office hours, you may contact a local emergency veterinary hospital or an animal poison control center. 

You can reach the ASPCA Animal Poison Control Center at 888-426-4435 or the Pet Poison Helpline at 855-764-7661.

Using multiple medicines can sometimes change how your pet’s medicines work or increase your pet’s risk for serious side effects. Always tell your veterinarian about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements that your pet is using.

Before using omega-3 fatty acids, make sure that you tell your veterinarian if your pet is using any of the following:

  • Anticoagulants such as aspirin, clopidogrel, heparin, warfarin, etc.
  • Corticosteroids such as prednisolone or prednisone
  • Cyclosporine
  • Nonsteroidal anti-inflammatory drugs (NSAIDs) such as carprofen, deracoxib, or meloxicam 

This may not be a complete list of medicines that can interact with omega-3s. Always check with your veterinarian.

  • Keep all supplements out of the reach of children.
  • Wash your hands after giving omega-3 fatty acids to your pet.
  • Do not handle fish oils if you are allergic to them.  

Call your veterinarian or veterinary emergency clinic immediately if you suspect your pet has taken more omega-3 fatty acids than intended.

If your pet misses a dose, give the fish oil when you remember, and then continue giving it at the regular time from then on. Do not double the dose or give an extra dose.  

Omega-3 fatty acids capsules and oral liquid should be protected from light and stored in a cool, dry place away from heat and moisture. If the product has a bad smell to it, discard it without using it.