Fish Oil

By Rania Gollakner, BS, DVM, MPH

What is fish oil?

Fish oil (brand names: Eicosaderm®, Dermapet®, Welactin®, AllerG-3®) is a supplement derived from coldwater fish, such as salmon. Fish oil is rich in omega-3 fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA and DHA act as anti-inflammatory agents, and therefore can be used for inflammatory diseases including skin allergies (atopy) and dermatitis, arthritis, kidney disease, heart disease, inflammatory bowel disease, diabetes, epilepsy, and some types of cancer. Fish oil is used widely in cats and dogs, as well as horses.

Dietary supplements are substances that can be used to supplement the diet, such as vitamins, minerals, amino acids, herbs, botanicals, enzymes, and probiotics. While many supplements are sold over the counter, they still contain ingredients that have biological effects that should be managed by your veterinarian. Follow your veterinarian’s directions and cautions very carefully as their directions may be significantly different from those on the label.

There are differences in how countries regulate supplements. In the United States, these substances are not as vigorously regulated by the FDA as other medications, which means they can be sold without the manufacturer proving their effectiveness, safety, and without a guarantee of consistent or accurately reported ingredients. In Canada, products that have been evaluated for quality, safety, and effectiveness by Health Canada and authorized for sale will have a license number on the label.

How effective is fish oil?

Fish oil has been studied in animals more than most dietary supplements, and studies show that fish oil is effective for treating allergic skin disease and some types of cancer. With other conditions, more studies are needed.

How is fish oil given?

Fish oil is given by mouth in the form of a liquid or capsule. It may be given with or without food; however, if stomach upset occurs when dosed on an empty stomach, give future doses with food. Fish oil can easily be mixed into wet food. Measure liquid forms carefully.

This medication can take up to a few weeks before full effects are noted, but gradual improvements are usually noticeable.

What if I miss giving my pet the supplement?

If you miss a dose, give it when you remember, but if it is close to the time for the next dose, skip the dose you missed and give it at the next scheduled time, and return to the regular dosing schedule. Never give your pet two doses at once or give extra doses.

Are there any potential side effects?

Fish oils are generally very safe. Side effects, particularly at high doses, may include diarrhea, vomiting, delayed wound healing, sleepiness, a fishy odor to the breath or skin, increased itchiness, or an oily coat and skin flakes. Discontinuation of the supplement should resolve these side effects. In cats, changes in blood clotting can occur. Serious side effects include persistent stomach upset, inflammation of the pancreas (pancreatitis), abnormal bleeding or bruising, or heavy metal toxicity characterized by appetite loss, incoordination, or seizures.

This moderate-acting medication may last for several days and may last longer in pets with kidney or liver disease.

Are there any risk factors for this supplement?

Fish oil should not be used in pets that are sensitive to it. Do not use unreputable sources of fish oil, as heavy metal toxicity can occur. Fish oil should be used cautiously in pets that are also taking anticoagulant medications or that have blood-clotting disorders, as this supplement can increase the anti-clotting effects. It should be used cautiously in pets with diabetes, diarrhea, or a history of pancreatitis. Fish oil should be used cautiously in pregnant or nursing pets. High doses should be used carefully, as vitamin A overdoses can occur.

Are there any drug interactions I should be aware of?

The following medications should be used with caution when given with fish oils: anticoagulants, doxorubicin, and non-steroidal anti-inflammatory drugs (NSAIDs).

Vitamins, herbal therapies, and supplements have the potential to interact with each other, as well as with prescription and over the counter medications. It is important to tell your veterinarian about any medications (including all vitamins, supplements, or herbal therapies) that your pet is taking.

Is there any monitoring that needs to be done with this supplement?

There is no specific monitoring that needs to be done while your pet is taking this medication. Your veterinarian may monitor your pet to be sure that the medication is working. Monitor your pet at home for serious side effects.

How do I store fish oil?

Store in a cool dry place and protect from sunlight. Some products require refrigeration after opening. Follow storage recommendations according to the bottle label.

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility.

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