Fish Oil for Cats with Arthritis

By Jennifer Coates, DVM on Aug. 23, 2013

First and foremost, cats with osteoarthritis need to stay slim. Lugging around excess body fat puts undue strain on joints, resulting in pain. Also, adipose tissue (fat) is now recognized as an important producer of hormones, many of which increase inflammation in the body, including the joint inflammation associated with arthritis. I like to see my feline arthritis patients just a tad “too” skinny — say a 2.5 on a 5 point scale where 3 is usually considered ideal.

Omega 3 fatty acid supplements, typically derived from fish oil, can also be helpful because of their anti-inflammatory properties. Several studies have shown that arthritic cats fed high doses of omega 3 fatty acids tend to demonstrate reduced lameness and greater activity than do arthritic cats who do not receive the supplements. Note, however, that I said “high doses.” Veterinarians differ on the amounts that they recommend, but everyone is in agreement that a few drops of fish oil every now and then aren’t going to get the job done.

To determine an appropriate dose of fish oil for cats, we need to break the substance down into its primary active components — eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The studies that have shown benefits associated with these supplements used differing doses. One that I’ve looked at fed cats a diet containing about 400 mg combined EPA and DHA. Other papers say that 600 -700 mg combined EPA and DHA per day is a reasonable level to aim for. A typical 1 g fish oil capsule designed for people contains 300 mg of EPA and DHA. Therefore, I think it’s reasonable for owners to mix the contents of one of these enormous capsules in with their cat’s food in the morning and another in the evening, with perhaps another one thrown in every so often for good measure.

But here’s a problem you may not have thought of. My husband’s bottle of fish oil capsules says that each one contains 10 calories. If you’re giving two or three of these to a cat every day, those calories can add up. “It’s just 30 calories,” you might be thinking, but if we’re trying to keep these cats slim, they could very well be eating less than 200 calories per day. Fifteen percent of calories from a fish oil supplement does seem a bit over the top, doesn’t it?

Perhaps this is a good reason to consider going with one of the therapeutic diets that has been nutritionally balanced and designed for cats with arthritis. Or, if you’d rather go the supplement route, I’d recommend combining all this extra fish oil with a food that is relatively low in fat and calories and keeping a close eye on the scale.