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Latest health and behavior news and advice from the veterinarians at Tufts University.

Features March 2018 Issue

Improving Dogs’ Arthritis Pain With Diet

Evidence keeps accumulating for certain ingredients. In at least one case, exact amounts are recommended.

When you choose a food for your arthritic dog, how do you know which claims for joint pain improvement you can trust?

"Supports Hip & Joint Wellness.” “Mobility Support.” “Support Joint Health.” “Joint Care.”

No dog treat or dietary supplement is allowed to say it actually treats or cures arthritis. That would be a health claim — and a flagrant violation of Food and Drug Administration regulations forbidding health claims on products that haven’t been proven with clear-cut scientific evidence, meaning research and clinical trials conducted according to strict protocols. Health claims are generally reserved for drugs, not foods or supplements you can get without a prescription.

However, any food labels are allowed to have what are known as structure/function claims that say their ingredients “support” or “promote” joint health. Those marketing bursts at the beginning of this article were taken from actual packages of dog food.

At a casual glance, a structure/function claim might seem pretty indistinguishable from a health claim. But dog owners should treat such claims as red flags and do more research if the claim is the main reason that they are purchasing the product. Dog food is a crowded market, and these claims can be used to help make an ordinary product stand out from the rest of the pack. Pet owners should ask their veterinarians to help them sort out too-good-to-be-true marketing claims from proven treatments.

For all that, the evidence for certain ingredients added to dog food to treat joint pain is “decent,” says Tufts veterinary nutritionist Deborah Linder, DVM. While the research is not always of the gold-standard variety — double-blind, placebo-controlled trials that are published in veterinary journals only after passing muster with a team of independent scientific experts who review the trials for study design and overall quality — preliminary studies do exist, and some dog food manufacturers have gone ahead and tested products on their own. And the results in a number of cases have been promising.

Herewith, the skinny on three ingredients sometimes added to diets for joint health or administered to dogs as dietary supplements — and, when possible, the amounts thought to provide relief for a dog who is suffering from arthritis.

© Merrimon | Bigstock

While some dogs really do get around better with diets — or supplements — touted to alleviate joint pain, keeping trim and exercise moderation are the centerpieces of treatment for a dog with arthritis.

Omega-3 fatty acids “Omega-3 fatty acids can help alleviate joint pain by decreasing inflammation,” Dr. Linder explains. The evidence for their efficacy is stronger than for other ingredients, she adds. But it should be omega-3s from fish oil — which come in the form of compounds known as EPA and DHA — rather than from plant foods like flaxseed oil, whose omega-3s are known as ALA (alpha-linolenic acid). It’s not that the omega-3s in plant foods are incapable of helping. But it’s EPA and DHA that have been shown to have pain-relieving effects, and dogs’ bodies are inefficient at converting the omega-3s in flaxseed oil to the type found in fish oil.

How much is right? It’s a formula: anywhere from 310 milligrams to 370 milligrams of EPA and DHA combined, per kilogram of body weight, to the 0.75th power. Huh?

There are three steps to figuring out the correct amount for your pet. Let’s say you go with 350 milligrams of fish oil (sort of in the middle between 310 and 370), and your dog weighs 40 pounds.

Step 1. Convert 40 pounds to 18 kilograms (each kilogram of body weight amounts to 2.2 pounds).

Step 2. Multiply that 18 kilograms to the 0.75th power [18(0.75)], which is 8.8. (Your phone can do this in scientific mode if you turn it sideways.)

Step 3. Multiply 8.8 by 350 to reach 3,080 milligrams (or roughly 3 grams) of EPA and DHA combined.

Seem complicated? It’s just one of the reasons you should work with your veterinarian to choose a food with omega-3s for your dog’s joint pain if you want to try that route. A veterinarian can also prescribe a therapeutic food formulated with arthritis in mind, which is a more reliable bet than a dog food for arthritis that you can buy over the counter, as it is more likely to have gone through clinical trials by the company. A therapeutic diet available only by prescription from a veterinarian can even have a health claim rather than just a structure/function claim. The FDA recommends, in fact, that diets for dogs labeled with therapeutic claims should be available only through a licensed veterinarian — or retailers and Internet vendors under the direction of a veterinarian, with comprehensive labeling and other manufacturing information available only through veterinarians. This ensures that the diet, now acting as something of a drug, is safe and appropriately chosen for your pet.

A veterinarian can also say whether the food is appropriate for your dog in general. For instance, a food to ease your dog’s joint pain that also is very high in calories (and there are some) is usually not a good idea. Excess weight from extra calories puts more stress on a dog’s already-compromised joints, only adding to his pain.

Of course, you can also go straight to dietary supplements rather than try to get omega-3s into your pet with food. Some people might prefer the food because their dog hates taking pills. For others, pills are easier. A site that tests the quality and purity of various dietary supplements is It will list omega-3-containing supplements that it has verified through independent research will contain the amount of omega-3s the label says it does, and it will let you know if they are in a form that’s readily absorbable and free from contamination.

Glucosamine and Chondroitin These two ingredients, together known as glycosaminoglycans, make up the building blocks of joint cartilage. The thinking is that a glucosamine-and-chondroitin combo may help protect joint cartilage that is damaged but not yet destroyed, and in that way can help stave off the bone-on-bone contact that causes great pain when joint cartilage between bones completely wears away. The two substances are also believed to act as an anti-inflammatory right in the joint and are thought, too, to help return joint fluid to its proper consistency. Normal joint fluid is thick and viscous, but as arthritis progresses, it becomes watery and therefore a poor lubricant.

How well do they work? “There have been a bunch of studies, and doses are all over the place,” Dr. Linder says. “The bottom line is that it seems like glucosamine and chondroitin are helpful in some dogs, but in others, there is no benefit. The good news is that there have been plenty of safety studies, so we don’t think it’s harmful to give it a try as long as you select a high-quality brand.”

The doctor points out that foods do not always contain the levels of glucosamine and chondroitin found to be helpful in scientific research — not even therapeutic foods that have to be prescribed by veterinarians. A better bet, if you want these substances to have an impact, is to go for supplements, working with your dog’s vet to choose the right one.

Note that if a glucosamine/chondroitin supplement is going to work for your arthritic dog, it’s not going to work overnight — so don’t administer it for a week and then give up in frustration. You really need to commit to giving it to your dog for six to eight weeks — or even longer — and then evaluate whether it’s helping. If you’re really not seeing any improvement after a good couple of months, discontinue the supplement and save your money.

Green-Lipped Mussels Weird but true. These sea creatures are another source of glycosaminoglycans that make up joint cartilage. And some studies showed an improvement in dogs’ arthritis pain when green-lipped mussels were administered either as a powder supplement, included in a treat, or infused into the diet.

What’s the therapeutic dose? “We need way more studies to know the optimal dose,” Dr. Linder says. “There has to be more systematic review, with control groups and treatment groups in different canine populations — overweight versus pets with ideal body condition, and so on. It’s all very murky right now. If you want to try it on your dog, this is definitely one that you need to include your vet on so effects can be monitored at particular dosages.”

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